Battery repair is an urban myth!

[@kenibnanak5554]

I don't know what to tell you. I just took a totally dead in every way DeWalt 20v battery and did the jump trick for only a second and now it charges and runs my drill just fine. Perhaps it is best to say some batteries are truly dead (or have a broken internal connection), while some others can still be saved via this method. If you unscrew the 20v battery case you will find a carrier inside containing size 18650 batteries. In most Dewalt battery packs they use a brand with a safety cap on one end that trips if a battery is discharged too much, or over charged. If after voltage testing each of the batteries you find a dead one, check to see if the safety cap is tripped. It can be reset by pushing in with a dull pin at one of the vent holes surrounding the cap. Push to it clicks, then recharge that battery with a Lithium battery charger designed for 18650 batteries. Check the charged voltage. It should be 3.6 volts or thereabouts. If a tripped safety cap is all that was wrong that cell can now be reinserted into the Dewalt matrix The battery pack can now be reassembled and used as normal.

[@punkinhaidmartin]

Whenever I have a question about an electronic component, I ask a carpenter. If he doesn't know, I ask a brick mason.

[@TheSmartWoodshop]

yea! don't ask this carpenter about electronics! Notice this vid was a poke at magic fixes on KZbin and had nothing to do with battery repair. I was a licensed Avionics Technician in the late 70s, but that goes back to the days we sodered resistors and made circuit boards so it wouldn't help with today's electronics. My fix for batteries is to buy a new one.😎🤙

[@danielbuckner2167]

Fix, what fix? You didnt know the problem and started guessing and playing with it and it still had a problem. Start by disassembling the pack housing. If you cant then just stop there. Ok, for those who have theirs open now, remove the power feed to the board, then the ground and set aside. Now remove the battery pack cells and unweld them. If you dont have the right tools then stop there. Soldering lithium cells doesnt work very well and you risk overheating them. A welder specifically made for this or a tig can be used to unweld and reweld the nickel strips later. Once the cells are apart allow them to come to a resting voltage and identify the bad ones, good ones, and so-so ones. Toss the bad ones, build cell packs with good ones and lastly build packs with the so-so ones if you like. You can always practice on the bad cells first to get your method down too.

[@tomjen6471]

You should make a video on this you would like you know what your doing

[@chasingsunsets380]

Daniel is right about having the correct tools and knowledge. You can test the individual cells and find bad ones and replace them. Another thing is swap out the electronic board and find out if that is bad. Now make a decision of what is cheaper, getting tools needed to save one battery or just getting another. I do not have a welder that welds the batteries properly so I would not bother but then in over 40 years of working with Nicads and now lithium, either the generation of tools has changed or the technology has before I have had enough bad batteries to invest in something I would use once or twice. Buying 3rd party brand batteries on line is just to cheap.

[@khooleo]

Cool you know some shit, don't need to be a dick tho....

[@joevangorder1006]

Yeah, I'd rather drag my nuts through broken glass than have to start dismantling and changing cells around on these already disgustingly expensive batteries...I hear Dewalt will exchange any battery within 3 years of the date on the pack which they absolutely should at this price.

[@sal8349]

Excellent advice

[@sctexan5392]

My understanding is that the hack only works if the bad battery voltage gets to low for the charger to recognize. I did it on 2 batteries that the charger didn't register, and it worked.

[@MrGlenburton]

Connect all of the pos/neg connections together from the 2 batteries then you will jump all of the cells not just the 1 (that is why there are so many connections on these batteries: multiple cells)

[@georgeevansshow9745]

there are 6 3 v cells and they are in series with one pos and one neg to the circuit board. I tried to jump start the cells with 2 14 v chargers by bypassing the board , it didn't work.

[@matthewchrome5144]

Yes, 100% it does work. For 7 months my Porter Cable 18 watt battery would not charge. Circa May 5, 2023. I placed positive to positive and negative to negative. I waited 3 seconds & attempted to charge it, but it failed. I replaced both wires and waited for 7 minutes. In my hand, the battery was extra warm. When connected to its power drill, it operated. However, it would not charge. I Recall Where Someone Said Hot Or Warm Batteries Will Shut Down A Battery Charger. I waited for battery to fully cool. I re-connected its battery charger & it fully charged. Since May 5 it has maintained a charge.

[@JohnWick-yt6rv]

Yeah with these flex volt batteries, when the light indicator shows 1-2 bars, shows fully charged/won’t charge on the charger, and runs 20v tools but not 60v tools, there is almost always one dead cell within the 15 cells inside, and that one dead cell causes the circuit board to then unbalance the other 14 cells, causing a repair nightmare. All of the flex volt packs I’ve been into/repaired had exactly one dead cell and performed identically to the one in this video. Not easy to fix them internally either, everything is caged together. They are expensive so I went through the trouble and taught myself to fix them lol

[@Tensquaremetreworkshop]

All the terminals are brought out for the charger to equalize the charge. If there is one cell that is zero or very low, you have a dead cell. Open and extract the cells (there may be two in parallel- 4Ah are twin. Usually both will be 'dead') Order replacement 18650 cells, and solder them in. Charge. Job done. I have done this with DeWalt batteries.

[@kylek29]

I've done that to a few Ryobi batteries as well. It's a good option if warranty isn't possible.

[@davefink2326]

Have you come across any KZbin lessons on this process?

[@AsiAzzy]

In addition charge all the cells individually at start. For the parallel cells it's highly important to have about the same capacity and state of charge when hooking them in the pack. And for the series cells if one is very low state of charge, the balancing circuit might prevent the charge function thinking is a dead cell. So charge all cells invidually before to make the pack with same state of charge for all cells. then the normal balancing charger can do it's thing. Ballance chargers are quite bad for charging a pack with one empty cell. Always is best to charge individual cells at first. I sort my cells by capacity before (with a clever charger-discharger where i first charge fully, then discharge to certain voltage and see the capacity between full charge and that voltage) and by internal resistance (by measuring voltage drop over a big load for short time, or the clever charger can do it for you. The internal resistance is a tell-tale about state of oxidatiation and age and how much life is in it. For a pack you need all cells to be in the same range of (tested) capacity and adequate (similar) internal resistance.

[@therealchayd]

I don't think there's any "quick hack" for Li-ion battery repair, short of dismantling it, removing the cells and testing and replacing or charging and re-balancing any defective ones (not a job for your average Joe), especially if they've been left empty for too long, it totally kills them. The rule of thumb is to keep batteries between 20% and 80% of capacity and aim to top them up every 6 months if left unused.

[@plasmar1]

the sideways way to attempt to "re-balance" the batteries(based on what should be happening naturally) is add a small load to the battery(bypassing the circuit protection aspect) and let it balance naturally; however this isn't something that should be done overnight or similar(if stuff can go wrong it will go wrong:P).... idea is they will equal out over time to some extent; it's not great but works to balance batteries that are near balance ** analogy.... if you have 2-3 half cups of water and one only has a quarter, if you force the water to circulate, they will naturally even out but just based off what is left in the batteries

[@workingmanrondoyle3287]

I had two 20/60 flexvolt 6 amp/Hour batteries replaced under DeWalt's warranty. They were doing the same thing yours are doing. They had me read the serial number to them an told me they would send two new batteries out as replacements. They told me to drop the defective batteries off at a recycling center. Great video Ron👍👍 Keep up the good work. If you call this into the warranty dept. Please let us know (viewers) about your experience in the replacement of your defective pack. Dewalt knows about theses issues and this Would make a great video.

[@rstephe]

Recommend taking it apart and sperate the cells. Using a meter you can find the faulty cell and using the numbers on the outside of the cell order a new one and replace it. A lot cheaper then buying a new pack.

[@razzix2]

Likely out of balance cells. Crack open the case and check for a dead cell. Balance the pack and/or replace the faulty cells. You can get 10-20$ battery balancers intended for RC/Quads. Balance leads with alligator clips to grab the battery tabs and you won't have to even break down the pack. If there are any smarts in the pack the boards are pretty easy to come by too. Boom - repaired.

[@robertkopp1534]

This is the correct way to do it, it can balance over time tho. I got a replacement pack for one of mine from the manufacturer and they did not provide a return label, so I grabbed it after 9 months with the intent to crack it open to get the good cells for my powerbank, but it balanced itself out and charged again. I did stress it too much with about 5 charge cycles a day when I had a lot of sanding to do, so they probably overheated a bit. I still should replace the bad cells.

[@gregoryperkins2180]

Whenever connecting 2 batteries together always put an inline fuse into 1 of the wires. this will keep a shorted battery from killing a good battery. maybe avoiding a fire.

[@Adanacon]

It’s simple The battery has dropped below its cutoff voltage. Therefore the charger won’t recognize the battery and stop charging. By giving it a jolt your bringing it slightly above cutoff so the charger will recognize the battery. Would be nice if the charger had a recondition mode that would do this for you, because we are throwing out batteries that are still good. It’s perfectly fine to jolt your battery quickly . Overcharging is the real problem or dropping way below cutoff because you will swell the cells and then they are done. In this case I believe you have a defective cell that is not able to recover ....very common.

[@russellchevalier3606]

Disassembly and replacement of the cells is the only reliable way. 90 days is a lousy warranty for batteries expected to run hundreds of charging cycles before replacement. There are other brands that do a far better job standing behind their product.

[@gonzowarburn7045]

Lithium are deep cycle, but they don't all charge, dissipate, and recharge the same. When one cell is weak, the charger will say the whole pack is fine or defective, when it's not. Look at Glen Burtons comment below. Can't wait to see what the tool companies will try and do to stop this bypass method, and then the methods KZbinrs come up with to bypass that! Support right to repair (see Louis Rossman KZbinr) laws, the fight is going on now, and support open source tech (like open source ecology). Car companies are already trying to make it so that you can't even open your own hood. And the "anti-theft measures" they put into power tools (coming very soon) have to be "activated" which, not only jack up the price but, will turn into "subscription services" soon. "You will own nothing and be happy" Slavery is Freedom. Start now. Hack, mod, build, tune and diy forever!

[@richardsandwell2285]

Carefully take the battery apart, use a multimeter to find the dodgy cell or cells, usually it is just the one bad apple, break off the Nickel strapping, beware of cutting fingers it is so sharp, simply fit in a new 18650 battery, you will need to re spot weld the nickel straps onto the new cell. Plenty of videos available showing the welding of battery cells.

[@cnnrstanley]

Because of the “flex” in the 60v batteries, the electronics are known to act up and fail. The switch between 18v and 60 is not always robust, and causes premature failure.

[@benshock9710]

when all else fails, I recommend dropping it on the concrete floor from exactly chest height. one time.

[@mountainman5292]

That's how The Fonz fixed the jukebox! A little persuasion.

[@UserName_no1]

@@mountainman5292 My grandpa used to smack the side of the TV set when adjusting the *rabbit ears* didn't work.😁

[@mountainman5292]

@@UserName_no1 I'm sure your grandpa was a good man, but he obviously wasn't as cool as The Fonz.

[@UserName_no1]

@@mountainman5292 That's kinda like art though isn't it? Subject to the observers interpretation. Besides my grandpa was real, whereas Arthur Fonzerelli played by Henry Winkler was a character on a sitcom. To put things in perspective. Respectfully so.

[@scottkasper6378]

User name checks out

[@007balzak]

I just tried it today on a battery that has not been used for 2 years! I had it connected to the good battery for 5 mns. It worked like a charm!

[@TheSmartWoodshop]

Cool, I wish it worked for me

[@jeffsiegwart]

I built a DeWalt 20V battery tester that tests individual cell pairs (two batteries in parallel). The battery contacts allow for the individual testing of each of the five battery cell pairs. I give each cell pair an equalizing charge and then discharge them, while monitoring each cell pair's voltage. My tester produces csv data for MS Excel. You can use the analysis data to determine if replacing some of the cells is worthwhile.

[@narsbars9626]

Check the voltage on the old battery and don't try to recharge unless you can carefully, slowly, bring it up to 6 or more volts. You will see if you are having any effect. One battery cell may be lower than the rest throwing off the balance but you can sometimes overcome that with a jumpstart if you bring the voltage up enough.

[@TheSmartWoodshop]

That is long behind me and the only battery I have ever had an issue with.

[@michaelstlouis2472]

if the wire gets warm or hot use a thicker grade wire. you are not leaving it connected long enough. again i have save 3 batteries with this method. it works

[@shepherdguy]

I know this video is old now, but when considering this process, people need to understand the physics of how the battery works and then you can understand whether this method is a myth or not. The batteries have an electrolyte that under normal circumstances form small crystals. Over time, these crystals begin to form from smaller crystals into larger crystals and they lose their ability to hold a charge, and the charger is only capable of charging the smaller crystals, then prematurely shuts off when the smaller crystals fully charge and the charger "thinks" it is complete. But in reality, only a small percentage of the crystals are fully charged. This forming (or clumping) of the crystals happens over time and you typically don't notice the small gradual drop in its ability to hold a charge until it gets really bad or you compare it to a newer battery. In the reviving process, what the negative to negative and positive to positive do is it heat up the electrolyte and re-dissolves the crystals. The dissolved crystals can now form back into smaller crystals from the clumped larger ones, thus allowing a full charge on the battery to occur. This is not a new trick, I have been using it for about 20 years now periodically. A co-worker in the maintenance department years ago taught me about the process and I used to use it to revive old cell phone batteries even before the Smartphones came out. The process, if not careful, can be dangerous. The best method is to use a battery with a higher rating (for a Dewalt battery, use a marine battery if available). You don't have to use a higher rating but it will take longer if you don't. Either way, I myself would not use another DeWalt battery as the process will heat "both" batteries and no sense in doing that to a good battery. The idea behind the process is to heat the electrolyte somewhat slowly. Negative to negative, then constant positive on the host battery, but small taps with the positive lead on the bad battery...no more than a few seconds at a time. perform the process with several taps until it becomes fairly warm, stop for 10 minutes or so, then repeat the process again with several taps. Do this for 3 to 4 cycles to get all of the electrolyte fully dissolved and I think you will find you have a renewed opinion about whether the process is a myth or not. One more thing, I mentioned earlier that this process can be dangerous, and as such, ALWAYS use gloves and Safety Glasses when performing this process - Face shield is even better. I'v never had a battery blow up on me but I also never become complacent enough to think it will never happen.

[@glenolzewski6714]

I used a battery charger the one that charges your car. I set it to the lowest charge hooked it the battery for 10 seconds. And put it back on its charger. The battery now holds its charge and works great.

[@jasonsodyssey]

I have used the same method to fix my battery, just needed a jump start from a more powerful charger I guess.

[@Dan_dmandtm]

I hooked a fully charged 18V Dewalt to a bad one that wouldn't charge and left them attached for 45 - 60 minutes. The good one will charge the drained one. After that, the bad one was able to fully charge on the charger and worked fine. Left hooked together, the batteries would eventually equalize to the same charge level.

[@rickk6997]

The only way I have seen this work is by opening the battery up and hooking up directly to the battery, bypassing the circuit board in the battery. Get a small charge back in the battery from another battery and then put it back together and try charging it in the charger. Supposedly the electronics in the battery will not let it charge if the batteries charge falls below a minimum level .

[@johng.1703]

many of these batteries when they report as "dead" are not actually dead, it's usually that they are locked due to a imbalance in the cells that is outside of the programmed spec.

[@mtl111mtl]

The best way ( and lowest cost ) is to open the battery pack up and change the cells. You get a newish battery at half the cost. I some times see batteres at home depot selling for $10 because the model is out of production, I take the cells out and put it into my battery pack. I have been doing that for over 25 years.

[@RK-kn1ud]

This depends on the battery design/manufacturer. Lots of manufacturers are starting to include memory chips into their batteries/tools that log any failures during charge/discharge. When you hit the programmed limit, the controller on the battery/tool will no longer allow the battery to operate a tool...regardless of the cell condition. There are probably ways to circumvent this, but it is increasingly becoming more difficult to do a cell swap. Without "right to repair" laws, it will probably become nearly impossible to do.

[@Metroid-rg9pn]

Exact same problem for me. Tried the same method you did. In each of those videos, not even a single light was showing. A single light was showing for both of us, so I think our problem is different. Thanks for putting up this video so I know I'm not alone!

[@TheSmartWoodshop]

Glad it helped

[@richturner5176]

Could it be possible that the battery’s charge state led’s are burnt out? Try a volt meter to see if this is the case. All the best

[@bw8771]

Internally these batteries are comprised of a number of cells. Jump starting it, as you tried, will only work if the battery has been allowed to discharge past its lower limit whereby the charger will not attempt to charge it at all. The most likely issue is that one or more of the cells is bad and needs to be replaced and that cal only be done by disassembling the battery, finding the offending cell/s and replacing them.

[@darylcheshire1618]

the other youtube gave it about 25 minutes on the good battery, positive to positive and negative to negative. Check that it isn’t overheating/melting don’t leave it unattended. Buy crimp tabs so you can attach wires to the battery terminals.

[@chahahc]

Flexvolts are some of the worse batteries out there. What happens is when you use them in 60v configuration and discharge the batteries, if for whatever reason some of the cells get discharged unevenly, when you remove the pack to recharge, the mechanical switch that determines whether it's in 20v or 60v configuration springs back into the 20v configuration. When that happens the cells are completely shorted from 60v series to 20v series-parallel and the cells instantly rebalance each other at like 100 amps of current, and either melts a safety fuse or kills the cells very quickly. Which is kind of ironic because the best batteries of any tool brand are the dewalt 20v batteries. Those ones are just that...BATTERIES, literally just lithium cells and a couple resistors, They don't have any funky battery management system circuitry that all the other manufacturers seem to put in their battery packs that always freak out for whatever reason and permanently kills the pack even though the cells inside are still perfectly good. And because there's no battery management system you can store them for long periods of time without worrying that the BMS will drain the battery and kill it. This also makes the dewalt 20v batteries extremely easy to rebuild. Open the pack, remove the old cells, spot weld some new ones in there and you're good to go. Brand new pack for 1/3 the price.

[@steveklick]

Great comment! Really sheds some light on these things.

[@WaltWW]

The Flex volts are duel voltage so the jump method does not work because the voltage goes through a circuit board first and not directly to the batteries

[@thefretfiend]

Not an urban myth at all! Replace the individual cells in the battery pack with new equivalent ones. They're readily available from dozens of reputable vendors, not cheap, but cheaper than a new battery pack. Plenty of vids on how to do it. Battery repaired. End of story.

[@TheSmartWoodshop]

The "Urban Myth" refers to magical fixes such as this and freezing them etc. Of course the parts can be replaced.😎

[@acemany1126]

@VictheWrench. He sure told you sucka!! End of story 😂😂😂😂😂😂

[@poduck2]

I've noticed multiple good comments here, but nobody has mentioned that once you get all the cells to the correct voltage, you may, depending on the battery, need to reset the microcontroller. This is the case with Echo batteries, for instance. On those batteries, there is a PIC microcontroller, and a programming connector with marked pins. One marked "reset". You would have to ground out the reset pin to reset the microcontroller. The microcontroller communicates with the battery management IC, as well as the charger, and if it isn't reset, it won't read correctly on the battery's readout, and it won't charge. Given that it's a "black box", I can only guess that there is some safety feature that once the PIC's software determines that the battery has a fault, it prevents it from being charged, and never retests to see if the fault has gone away. Given that those Dewalt batteries have a battery level display, it certainly has a microcontroller on it. It may need similar treatment.

[@Momentaryghost]

Recommend not using those fast chargers. That is why those batteries are going bad just an fyi. My dad has had 3 of his 4 flexvolt stop working using that same charger. Slow charging keeps these battery cells in decent shape. For fixing pull battery case apart separate cells, check all cells, charge all cells replace ones that get hot or won't charge. Repack cells and done

[@jgemeinhardt3955]

Hey Ron, yes there can be some restoration to lithium Ion batteries on a temporary basis but the fundamentals of the physics of these batteries eventually render it useless. As the batteries charge and discharge there grows over a period of time a spider web like network of connections at a chemical level that forms between the anode and cathode of the battery cells. As this develops these begin to rob the battery of it's ability to deliver current (and hold from a re-charge) as they essentially short each other out. BMS circuitry helps minimize the conditions within the battery that allows this process to grow but really only delays the eventuality of the chemistry. Obviously loads of continuing research are trying to solve this issue as well as current holding density. There are new technologies such as carbon based battery research but they remain very expensive and still in the developmental stages.

[@td1482]

Ron, there are videos on You Tube that show people taking a car battery charger and intentionally putting touching the probes to the wrong pole of the battery. They claim that this will break up that spider web network and allow the battery to charge again. Sounds dangerous to me, but if you wear a face shield and protective clothing??? Who knows?

[@josephdestaubin7426]

As I'm sure others have mentioned, one can sometimes have success by using a full battery to recharge a faulty battery to high enough level so as to get the charger to finish the job.

[@jonjonr6]

One thing that I doubt many people know, it's best to avoid charging batteries that are warm or hot. For example, if you have a 40v Ryobi mower, leave the battery over night before charging. If you put it on the charger right away, your chances of the battery dying are greatly increased. They don't have active cooling systems. And they are encased in plastic to keep you from touching hot parts. I suspect the same caution should be used with 18v batteries. If they are hot, don't put them in the charger if you can avoid it.

[@ryane6719]

Or buy makita that has built in protection.

[@darinb.3273]

@@ryane6719 I was going to say that lithium batteries aren't nickle cadmium batteries (those were the real work horses for rechargeable tools) they just had what was termed "battery memory". Lithium batteries aren't to be messed with (absolutely no OVER charging) they can potentially become a blow torch. And definitely DO NOT short the terminals same result the battery will become a blow torch and potentially explode. They DO NOT like excessive cold or excessive heat either and reputable companies WILL ALWAYS have built in protection for "HOT" batteries, circuits that check the temperature before sending power to charge.

[@davidwoods5095]

Thanks Ron, I have used your plans to build a tool trailer and last Thursday I purchased another trailer to build another set up. This one will be used by volunteer groups in the East. Referred another contractor to check out your channel as he just purchased a new trailer.

[@debohannan4315]

Your battery is most likely out of Ballance try checking each cell . There are connections on the top the most positive slot will be followed by a connection next to it that's the negative it shouldn't be over 4.2 volts that second to third should also be 4.2 and so on till you get to last 2 connections . The cells at 2.5 are concerted dead and need charging but if below 2 they should e discarded. The voltage should be between 4.2 to 2.5 volts but problem is they can get out of Balance some could get over charged and others under charged to get the right top voltage if this gets to bad it can cause a fire or destroy the cells . I have bottom balanced battery's by bringing up the lower cells to match the highest cells then your smart charger will top it off just fine . Sometimes the reason for unbalanced cells could be a bad (bms) battery management board board but lithium cells all have different resistance so lithium battery need something to help prevent out of balance

[@RadioReprised]

I use an old car charger with a 50 amp jump start setting. Hook the negs up then turn it to 50amp and just TAP the positive of the battery to the positive of the charger rapidly about 20 times then throw it on the DeWalt charger quickly and it usually charges fully.

[@ronniepirtlejr2606]

That only works on nickel metal hydride batteries ( NiMH) or batteries with nickel. You do not want to do that with lithium-ion. It will more than likely blow up in your face!

[@MarkH10]

Ron You have 8 or 9 18650 cells built into that housing. Take it apart and then check each cell. Replace the failing cell(s). Search. "How to fix a tool battery." My YT search yields a few dozen with thumbnails wherein the battery pack is approached in this manner. You also know 18650 may yield results.Then YT search Repair/Revive?recondition. Then Lithium or NiCad. So, in short, yes there is an answer, and 45 minutes will give you 3 videos you can make about your progress. Here is your final motivation.......... This topic yields over 1million views on several channels creating videos on this subject. If you get my drift. I hope you go viral.

[@SunriseCrawlers]

I have over 15 batteries and I run into this problem time to time. When the charger says it's full but one bar or 2 bars means you have a bad cell in it. Get the multi meter out and test each batter voltage and resistance.

[@SunriseCrawlers]

It takes a t10 security bit

[@davedisser8124]

The "jump start" trick only works with batteries where the battery shows zero bars and the charger won't charge it at all.

[@mysterytechknowledge3664]

Take a MultiMeter and test each cell for voltage.If one cell is a significantly higher voltage, you need to drain it. You can use a 12v light bulb with wires soldered to it for a load.

[@joemcmillan2089]

I have Ryobi, Craftsman and Porter Cable tools and batteries. Now and then one will not take a charge. My first fix is to wet the terminals with my tongue and place the battery back on the charger. Most times this works. The other fix is to run the battery completely dead by running the tool. Between the two fixes, my batteries have lasted for many years. All are Lithium and some are over 15 years old.

[@inharmonywithearth9982]

I have a 40v Dewalt battery that went so dead its green power gauge even went black out. I simply got two old rusty nails and pushed one in one of the two positive terminals and the other nail in one of the two negative terminals. I plugged in my little rayovac charger and touched the negative to negative nail and positive to positive nail. Held it there for long enough for it to spark. Then I put the sparked battery on the charger and it works!

[@carlthacker570]

Sweet

[@rickmaness3295]

I don't know which video you were watching but the one I watched said to hook the wires up positive to positive and negative to negative for a couple of hours to equalize the charge between fully charged and one that will not charge. It worked on my Dewalt batteries! But if you just touch it quickly you are expecting some magic spell to happen, use a little common sense with this! I know that it is possible to disprove any video on youtube if you do it wrong then cry (wolf) myth busted!

[@cravenmoorehead5636]

It absolutely works. Just as you are explaining. Reason being the battery is to low for the charger to pick it up. Usually around 16 volts. Jump it off a good battery until it is up to around 18.5. Then throw it on the charger and wala

[@cravenmoorehead5636]

The spark is telling you it is working. Leave it there for a few mins.

[@cravenmoorehead5636]

I have only tried it with the smaller batteries

[@markwiss]

I saw one video where all the terminals, I think 4, were connected left to right and the fully charged and the faulty batteries were left hooked up for 20-25 minutes. After that the faulty battery worked and later took a charge. How long did you keep them hooked up? Do you know if It is the battery brain or if these batteries have multiple 18650s, or other cells that can be replaced?

[@iamthemoss]

No arguing, batteries suck period. They don't last, they are expensive. Don't get me wrong but there should be standards. Just bought another Milwaukee M12 tool with two batteries for less than half the price of just two batteries. A heavy user will kill batteries in a year or two. For this reason I am still very skeptical about electric vehicles for daily use.

[@jmsbwr]

Amen! What the hell happened to corded tools??? More power and less weight and run all day. Unless you have to go up a 40 foot ladder to a church steeple, why go to the trouble and expense? If you have to drill one hole at the back of the barn or out in a stadium, take a brace and bit. Lighter and WAAAY cheaper than even one battery, much less the whole tool, etc.

[@annaplojharova1400]

Without proper diagnostic there is no chance to revive it and mainly revive it safely. The thing is, in cases the battery is salvageable (without replacing any parts), the cause most likely is imbalance between the individual cells (one is nearly full, other nearly empty). The electronic stops charging when the highest level cell reaches the full state voltage and shuts down the tool if the lowest level cell drops to the set minimum. If you manage to fool the communication between the battery and charger or tool, the only thing you get is underdischarge or overcharge of some cells, both may end up in quite a fireworks, mainly the overcharging... The safety is THE reason, why the charging get stopped when the highest voltage cell reaches the upper limit, even when the others are not charged at all. Acquiring some imbalance over time is normal and it is in fact one of the main limiting factor for the useful lifetime on cheap batteries. So the only possible way to salvage is to disassemble the pack, measure the voltage across individual cells and externally charge the lower ones to the level corresponding to the cell with the highest voltage. After that the cells become balanced again and so the pack starts working again, at least for some time. Better quality batteries have already build in a circuit doing exactly that, but most cheaper brands do not have any balancer in them, so are suffering from this problem, so rebalancing them may bring back extra life. With the higher quality brands with the balancer you won't be able to resurrect it anymore (without actually replacing the cells), but they won't end up in such state that fast in the first place.

[@WilliamJones-sf5pt]

Perhaps this is why Marine type generator batteries get deep cycled. Running them all the way out of juice first will allow every cell to be powered up more evenly. Car battery cells have to be placed closer together for greater amps to turn over the starter. So, generator batteries last much longer.

[@annaplojharova1400]

@@WilliamJones-sf5pt Traditional accumulators (so all lead acid, NiXx,... ; not LiIon) cells can handle some overcharge (the only limit there is the water recuperation and heat dissipation ability), so the balancing is done by driving all cells slightly into overcharge (the lowest charge one gets its charge even when others are full), so do not need any special balancers to equalize the charge, just full charge from time to time. However Li based cells start to degrade extremely fast (or often turn into a flamethrower) when charged over their limit (about 4.2V/cell for the common ones), so any overcharge must be prevented.

[@rhiantaylor3446]

I have had a lot of success "fixing" these batteries. I find the electronics is usually the problem so I charge directly to the cells with individual cell connections brought out so I can do this using an iMax b6 clone charger. Given the price of some of these batteries e.g. Bosch 36v 6ah packs, it is worth doing provided you know enough about these cells to do it safely !

[@georgeevansshow9745]

do you have a vid showing how

[@leslarson2642]

Removal of the battery assembly from the case may be necessary. The 20v tool battery packs are 5s assemblies, generally 2 or 3 sets of 5 in parallel. Measure the voltage across each parallel set which should give a voltage similar to a single cell, on the order of 4 volts for a single cell. In my experience, on a bad battery pack, the voltages will vary all over place, leading the packs internal BMS to shut off charging too early and/or shutting off the tool. The only way I have found to correct this problem is to charge each 2 or 3 cell group individually to approx 4.2 volts, max charge for the lipo batteries. Once I have gone thru that effort, the packs charge and discharge normally. It is normal for a pack to go 'out of balance' over time. A bad cell in a battery pack is more difficult to locate and will require breaking the connections between the individual cells in a group but that is another story. Jumpering a battery to get it to charge does not correct a cell imbalance issue.

[@TranTek]

Jump start like that wouldn’t work often over heat and can burn need to take it apart and measure each bank to see which set of parallel depleted and you can work isolate which is bad by removing the spot weld and see which one was the issue

[@ThriftyToolShed]

The pack has 3 sets of 5 cell groups and one of the cells in the groups of the 5S is charged to full so the charging is stopped there. One or more of the groups are not getting up to same charge level. (Unbalanced) You would have to take apart the pack and see what cells are low and replace those to get the pack up and running. Of course always better to replace all, but that would cost about the same as new pack cost. I like to keep packs going as long as possible so I have video showing replacing cell successfully on the flex volt and atleast getting some more use from it for around $5. Alot of time, but I enjoy doing it.

[@paulgerrard5518]

thrifty tool shed.... i had that exact problem on some dewalt knock off batteries..... all four had given up within 4 months of purchase.... took the first one apart, and one of the balance wires had pulled out of its solder... resoldered it, it charged fine... took second one apart, and exact same problem.... third also had the same problem....seems all the problems were caused by the same balance wire pulling loose because they were soldered with the cable too tight in the manufacture.... so any sudden jolt of the battery pack would pull the same cable out its solder... took a dewalt battery apart and this 'shouldn't' happen because of superior build quality... the forth battery pack problem was due to the spot welds breaking... resoldered, and it too was fine...

[@tattoosteveneo]

Tear it apart and put new batteries in it. I’ve done it several times with 0 issues. Just make 1000% sure you have the correct poles going to the correct ends.

[@melaniecotterell8263]

Easier said than done. You don't just pop in new cells, there is soldering, or spot welding require. But it will only cost 25% to 50% of the cost of a new branded battery pack, A 3 ah 12 volt (36 watt hour) pack has (3) 18650 cells that you can buy for ~$5 each.

[@patprr1756]

No issues you mean.

[@SgtPickledic]

I have a Kobalt Battery that was doing this, I removed all the cells and charged each one in a Cell charger, it fixed the issue i had 2 very low cells in Bank 2 and 3 "most packs have 3 banks that charge". What caused it is Over discharging the battery pack.. I had mine on my Leaf blower. There is no trick on fixing them as well unless you charge each cell by them selves. These packs are not easy to remove the cells as well.. You can buy modular packs that you can add your own cells without needing to spot weld for various leading brands.. Leaf blowers don't have much resistance when blowing, so it can allow the battery packs to sometimes run longer than they are supposed to, especially if you never lift off the trigger. Drills and most other tools have a lot more resistance when running so the batteries will shut off before you can over discharge them..

[@notscot6788]

You can also figure out if your gas tank is empty by using a match. Depending on the size of the explosion, there are certainly some deductions you can make. That's what you are doing with these batteries, amigo. Smart chargers are trying to sense defects in a series of batteries.... several in a row. Internally, the things that make them fail are things that you MIGHT be able to cure with a shot of current from a paralelled battery, but that is a blunt instrument.... like doing eye surgery with a machete. Once a fire starts burning up all your Paulk benches, there's a pretty good chance you'll limit your future chemistry experiments to paint, and stay the heck away from lithium cells. The chemistry, internal structures, etc. of lithium batteries is complicated, and it's why we have electrical engineers (EE's). Putting power at these densities into the hands of carpenters and mechanics requires a lot of engineering. For the same reason that you don't allow your car mechanic to work on the elevator in your skyscraper, you should pay attention to the tens of thousands of man hours that went into designing these charging systems. Those features are NOT there to make you spend more money on replacement batteries. They are there to keep you from burning down your house and watching your family cross the Rainbow Bridge. A single youtube video showing "good" results from an experiment that worked once in a row is not a recommended method for saving $50. It's luck, pure and simple. This isn't printer ink. It's a power source that can drive a foot long wood screw into a railroad tie. Do stuff like this at your own risk. ( I had a client once that wanted me to bypass thermal fuses in a fan motor because they were a nuisance and several had failed. I declined for sound engineering ethical reasons. This is the same thing. Does it work? Sort of. Does it bypass legit safety protection intended to protect the public? Yes. Is that ethical and wise? No. ) Buy new batteries. That is the solution until there are battery technologies that provide superior service. Stick to bench design. ( Love your designs, by the way. Top drawer stuff!)

[@travislewis9328]

Good point but those 60 volt batteries are anywhere between $100-$200 depending on the Amp hour I have 6 that are the same way just recycled them and got lucky and found a 2 pack of them for 100

[@DavesTreeFarm]

Why so defensive? Where do you think innovation comes from? So just be a good little sheep and pay outrageous prices for a battery. Got it.

[@carlbussmann7559]

Connect the two similar batteries as you have done: (+ -> +) and (- --> -). Leave them connected for 15 - 20 min then try. The electronics in the battery will not start the charging until there is a slight charge in the dead battery.

[@richardtucker5686]

crack it open, disconnect the individual batteries. check voltage with a multimeter on each individual (internal) battery. replace the dead (or dying) cells. resaulder the connections, and try to recharge. If no cell is low, swap out the pcb with a known good board.

[@emmettturner9452]

You didn’t even try to find the bad cell?! Next time, try the REAL fix before declaring all battery repairs to be “myth.” Yes, I know I got click-baited and responding it just going to raise your profile with the algorithm but I genuinely want you to learn from this. This is either a balance issue or a bad cell issue. Simple as that, though some bad cells only show it under load.

[@202wcox]

You can disassemble the battery and find several small ones inside. 1 or more of those has opened up completely or will show much lower voltage no load or you may have to apply a load. Anyway some of the small batteries inside that dewalt are good, some will test bad. Save the good for fixing another dewalt that goes bad. Or try to find new to put in that original battery. Or say my times not worth it and toss it. The battery you can fix with the method you described is 1 that was sitting around and the voltage went to zero. Use a decent voltmeter to test them individually.

[@rolfschubert1853]

As stated in one of the other comments, the individual cells must be at approximately the same voltage level in order for the charging circuit to work properly. Try charging the under voltage cell to match the levels of the remaining cells. If not possible, try discharging the remaining cells to match the level of the low cell. Keep in mind that below a certain voltage, the charger will not be able to recover the cells, so try the former approach before the the latter.

[@rogerwhiting9310]

Your jump start demonstration used to work on NiCd and NiMh battery packs. It doesnt work with Lithium batteries.

[@steelarms4235]

There is a programmed BMS in the battery pack, one of the cells voltages dropped too low, battery cells are no longer balanced, BMS is stopping the battery pack from being charged.

[@Samuel-I]

Robert Redford giving out 18v battery advice now?

[@williamrogers4290]

If that's Robert Redford it's a really old video!

[@Eden_M]

I see some mean obnoxious comments here that made merely for the purpose of insulting the guy. You guys don't contribute anything. As Matthias Wandel once said: " Well, I've made a KZbin video instead of a KZbin comment"

[@RolyRhodes]

You could dis-assemble the pack and find the week or dead cell. Then replace it... but it would involve de-soldering and re-soldering the connecting strips... I do it all the time... a lot cheaper than replacing the whole pack... 😎👍

[@frankjackson2439]

YOU CANT JUMPSTART FLEXVOLT BATTERIES!!! Flexvolt batteries have circuitry that switches the internal banks of cells to create higher voltage. If you try to jump start flexvolt batteries you will fry the circuitry. You can use this method on nicd and dewalt 20v batteries because the positive and negative poles connect directly to the cells with no circuitry involved. You can try taking apart the battery and force the cells to individually charge. Some times they can discharge to a point that the charger recognizes a bad cell and won’t charge the battery.

[@bernhardnizynski4403]

There may be one faulty/shorted cell inside the battery pack?

[@marcrj8111]

I didn't go over the comments so sorry if this is redundant. The battery to battery boost does not work with Li-ion battery. It does work with the older types of batteries. On strategic tools and high powered tools, I still stick to direct AC. There something about all this "chargning" necessity that just doesn't fit the "convenience" bill.

[@giromac1]

Batteries die for different reasons. One is that the level gets too low, and so the charger won't decide to charge the lithium ion battery, for safety reasons. This sort of thing seems to be the only thing you can "jump-start", getting it above the lower limit. On at least some Makita batteries, I've read that a chip inside it counts a number of strikes against it, so that if you try 3 times and it fails 3 times, it's marked as bad. If this is true, after that failure there is no way to jump-start it. Yours seems likely to be ok on voltage (it ran your tool), but low on amps (the power meter shows it is low, and it doesn't run the tool for long). I would guess it is just used up, similar to how a car battery eventually just doesn't have the cold cranking amps it once did. On others batteries, if really motivated, going through the cells and replacing bad ones would likely work. I wanted to do this with a few big ryobi batteries from a chainsaw, with two that died from overheating, and one from a limb dropping on it. This should work, either with spot welding in cells, or making a new carrier for it that is more like a traditionally AA battery supply with spring loaded connections. If done right you could even select your voltage and amperage, based on the wiring of cells. But that's much different than hoping to trick the charger into working again. This wear out. Batteries don't last forever, even rechargeables. Ridgid puts a lifetime warranty on them if you register, but while they have held up decently, I don't like the feel of their driver as much as my Makita, and of course it's also different than my Ryobi higher power needs of a chainsaw, pole saw, blower and lawn mower. Universal connections would help, but that's a whole different kettle. But having a unique and expensive ($150-200) battery is what had me buy an ok Ryobi chainsaw, where I have a few tools in the series, instead of an EGO one. Until universal batteries, remember to charge your seldomly used batteries at least a couple times a year, and know that you'll have to buy new ones eventually.

[@xanataph]

The only chance you really have is if there is a cell imbalance. If you open up the battery you'll gain access to the individual cells (although in those bigger batteries they are in pairs). Then you need a single lithium cell charger (like one of those cheap eCig chargers) that can change a single cell. And then you go through each pair of cells in the battery with this single cell charger - being very careful of polarity - until they are all charged up and sitting at 4.2 volts. There is no danger of overcharging as the single cell charger wll cut out (usually displaying a green LED) at the correct voltage. If you get a cell (or pair) that won't sit at 4.2 volts (or reach end of charge), then it's faulty and is letting the battery pack down. You could replace these cells. On the other hand if you get all the cells (or pairs) up to 4.2 volts your battery should now work just fine.

[@PeterPetrakis]

Anything can be repaired, whether it's worth your time is a different story. I've done it with laptop batteries for older models that want a king's ransom for a replacement. You can always sell them online for parts.

[@toddday1835]

You can open it up and charge each cell individually. Find out if there's a bad cell.

[@roby3291]

So many geniuses on here. I have seen it work and there are videos on KZbin, you know, the thing you all are watching? You can’t just try it a couple times. You have to keep doing it several times. Check the voltage each time.

[@TheSmartWoodshop]

Roby, I am amazed that this video which was a fun poke at the many magical battery fixes on YT which took very little time to produce continually rises to the top. My serious videos that take days to shoot edit and post don't even come close. Personally, I could care less about battery repair as the warranties are so good, I just get them replaced.😎🤙

[@TheMingilator]

you probably have a bad cell, these batteries charge in 20v mode which means 5s 3p (5 in series 3 in parallel) which means that the balance monitoring (the voltage between each of the cells in series) monitors 3 cells not just 1 or 2, best bet is to take the thing apart and get a multimeter on it and check for a cell (well 3) where the voltage is lower than the rest, that will narrow it down, I do not recommend attempting to replace the cell as at the bare minimum you will need a battery spot welder which are around $100, a proffesional might be able to replace the cell though

[@brownro214]

Even if the jump start worked, it would only be temporary. If you want to repair the battery to work like new, you would need to replace the cells inside the case. Open up the case and find out what cells you have then go online and purchase replacement cells. It will take some time, but it should be cheaper than buying new batteries. You have to decide which is worth more, your time or your money.

[@gogashalamberidze3828]

Hello, I had the same problem and I repaired it by charging each battery with 18650 battery charger. You just have to unscrew sides, not fully disassembly. Mine was almost new but I drained it.

[@MR-gp9ys]

What you need to do is put in a brown paper bag along with some wood chips and m&m's.. Bury it all in a cool damn place at last 5 feet down .. Than a week later take it all out.. Transfer the battery to a metal box now.. Throw it in a small river or creek. About 7 days later. Take it out and voila.. It'll be good as new...

[@wm1958]

Good grief man you missed the first and most important step. Before putting it in the bag you have to put it in a bucket off ice water and paprika mix for at least 20 minutes

[@R.AudioElectronics]

Funny humor can’t get enough of it!

[@anthonylee1536]

First thing to do is to measure the battery voltage. When you connected both batteries in parallel and both packs showed two bars - this is a good indication that the faulty pack was too low for charger to see. Even though this is low voltage, lack of knowledge and respect could end very badly.

[@jeremysutherland295]

Funny....my 6 hr battery went bad yesterday. Odd thing is a few guys at work have had the battery stop accepting charge where mine on the other hand stopped powering the tool but says is fully charged

[@danharold3087]

You can stand on your head but if there are dead cells it will never work without replacing them I am guessing the trick with charging from another battery would work if the voltage was below what the charger would allow but the battery was still decent enough to take a charge.

[@angelofermo1831]

Sometimes the LED on the battery stopped working so you think the battery’s dead when it’s actually fully charged

[@cannaboids1999]

You have a bad cell (one or a few of the AA looking batteries within). They're probably 18650 batteries. You have to open the battery and replace the bad cell. I've done it for Milwaukee, Ryobi, and Dewalt. You have to find a good source for the replacement cells because of so many fakes out there. Without proper soldering tools, it could chew up precious time, so sometimes I just buy new batteries. Batteries that come packaged in a "deal" may already be older and battery packs have a shelf life. If you can, return it to Dewalt or the retailer if you're within Warrenty and return/replacement window.

[@2littletime2sleep]

I think have one just like that in my van. There's actually nothing wrong with mine except the stupid battery charge gauge is bad. Exact same symptoms. I had to use it to finish drilling a hole while the other ones charged and it seemed to be full charge but it read low. Use it all the time now I just use it till it stops turning the drill. Even says "bad" on it in sharpie.

[@doctorlefthandthread]

I brought one back and didn't know it the battery indicator light wasn't working . It could be the issue there I did notice the wire heating up too when I got one to work.

[@rstige]

What is the voltage of the battery when it is fully charged?

[@waynejensen7689]

I have done this successfully to fix 12v, 14.4v, older 18v and newer 20v batteries, but never tried it on a Flex volt yet. Might have something to do with the setup of 3 separate 20v circuits in a Flex volt battery. I'm guessing some of the other contacts have to be used to create a parallel circuit of all 3 20v battery groups. Would help to have a schematic for a Flex volt battery to figure it out.

[@0one1two3five8]

@ronpaulk markH10 is correct you likely have atlest one cell in the pack where the voltage has dipped too low. When you disassemble the pack test the voltage of each cell. If none stands out as particularly low voltage, charge each cell individually and see with discharges faster than the others and replace the malperforming cell - oh and be careful lithium cells are easy to short and prone to catch fire. I think Jehu Garcia's channel has some good info on checking lithium cells. Best of luck! Shalom!

[@crazydumbsick]

Replacement of cells, rebuild the battery you need tack welder and soldering iron maybe special bit to open battery and I've never done the job but it seem simple.

[@mikeydesilva8197]

I just repaired flexvolt 6 AH 2016 battery . Removed covers checked voltage on all 15 cells , made sure all cells are close 3 volts or better. I found the first cell on the positive discharge side was flat line , 1bar on indicator. Repllaced it with recycled scooter bat. That video is on my channel If interested good luck.

[@marcchuck-you-farleytrembl2145]

Hook up the battery to a DC power supply, charge it about 1.5 volts over the battery rated voltage for about 20 minutes. This worked for me on a bad lithium Martercraft (Canadian Tire house brand) 20V MAX 4AH battery. I closely monitored the battery during this operation as I was concerned about fire. NOTE: This was a desperate move on my part as the battery was basically useless, only 1 light would come on. Before this operation I drained the battery. To my surprise, when I disconnected the battery from the DC power supply I had 2 lights when I checked on the battery. I then connected the battery to the charger and it charged as normal to full charge (4 lights). The battery is, so far, holding a charge.

[@PLAYBOYNOCOOLANT]

badass

[@GutsyGibbon]

Inspired by other KZbin tool battery rebuilds, I made an interesting discovery. I had a bad Black and Decker tool battery and decided to rebuild it. I bought the little welder and a set of new 18650's to replace the full set. Big surprise! When I went inside to start desoldering the wires, I found a sense wire that had broken. I resoldered it, and the main positive and negative leads that I had already desoldered. I put the battery back together and it is working just fine. I guess the welder and spare 18650 will have to wait until another of my batteries fail. So I think anyone that has a bad tool battery should at least open it up and check for a broken wire. A quick fix that cost nothing.

[@debeerpaul]

The bridge method worked for me. So sometimes it may be that you have a bad circuit inside the battery.

[@bloodswarms]

The title of your video... lol. The FlexVolt battery system me have more complex BMS/control boards, so I have no advice there. But I've repaired tons of other DeWalt battery packs. I've replaced cells in dead 20V Max battery packs many times, with a 100% success rate. Battery repair is hardly an urban myth.

[@stevendblois69]

The original inrush current when jumpstarting the dead battery sent it into hot\ cold mode. Cool the battery in the fridge. Then your charger will begin its cycle. Battery saved. Worked for me. Runs great.