Repairing a Milwaukee M18 Battery that won't fully charge

[@bigrock6059]

I use this technique all the time and I have revived a lot of battery packs. Another tip. You can see how much capacity remains in the cells by completing a Nor test using this type of charger. It takes many hours depending on the capacity of the cells ie. 4mah, 6mah, 9mah. The Nor test will charge the cell bank up to full capacity, discharge the cell bank to low voltage cutoff, and charge the cell bank again up to full capacity. Many of these battery packs can be recovered and have better than 80% capacity remaining. Thanks for sharing this video.

[@yousefalmarhoon8789]

Thank you sir, you just saved me from headache and losing some money I have the same problem with my 12.0 AH

[@jimnunes6286]

Good video, would be much better without the music, and explane what you are doing.

[@ToRo909r]

Dude you’re the only person with a great how to video, got 2 of my 9.0 working properly again. Thanks

[@KhoaDTNguyen]

Thanks for making the video. I just revived my 8.0 amh Milwaukee battery by doing this. This saved my a bunch of money and help me not throw away a perfectly usable battery.

[@danpaulsen7039]

Perfect video. Worked like a charm. I ended up with a perfectly good 9Ah batt that had been discarded because it would only charge to 3 bars

[@theriddler9963]

I purchased my Milwaukee 8.0 amp battery last year I couldn’t understand why it was already giving me trouble because it was a backup battery that I rarely use. It took a couple days using your method but it was well worth the effort for a $180 battery but I’m happy to say I got it back in service. Thank you so much for taking the time to make this very informative video.

[@allmycarsisbroke]

Where are you getting 8 amp batteries for $180? They're like $230 everywhere I look. If you buy two at once they come down to $200 each...

[@SloppyPlatypus]

​@@allmycarsisbroke2 years ago is a long time ago...

[@Billbobaker]

Glad to find this video I have that same problem with one of my packs. Three cells wont charge above 3.7 volts. Thanks for sharing it.

[@rictic63]

THANKS! I just ran into this problem on 1 of my M18 12.0Ah battery packs.

[@ljubuski1]

Thank you very much. Just fixed my xc5.0 battery thanks to this video.

[@michaelkeefer6799]

I'll have to give this a try. I have a 9Ah doing this and a 12Ah. Was literally about to dispose of it but decided to look up if there are any fixes for it. I know you shouldn't attempt to replace lithium batteries buy if it's one that discharged improperly during long storage then this might be a good fix! I leave a lot of my batteries fully charged and they sit in the garage where it gets hot and cold throughout the year so I'm not surprised I'm having issues with my batteries. But my 9Ah is probably 6 years old now and my 12ah I believe is 4 years or close to it.

[@BruceAlanR]

Helpful video! Judging by the pink (red) insulation on the ring terminals I’m assuming you’re using 22-16 AWG stranded wire for the jumpers. Correct?

[@weeeves]

Yes, that is correct. I used 18 AWG but 22 AWG is fine as well. It just needs to be able to handle 2-3 amps.

[@BruceAlanR]

@@weeeves Great! Thank you for the response.

[@wchitwood65]

Be very careful not to puncture or cut the plastic surrounding each battery just behind the parallel plates as you connect a jumper wire, it can short that battery which is tied to another two and cause catastrophic discharge and fire. You would think that Milwaukee would build a better balancing circuit for charging.

[@davidmeagher4909]

Thank you so much. This is exactly the same problem I have with one of my almost brand new Milwaukee battery packs.... I ran the battery very low in my impact driver installing a floor. I was really upset, thinking I had a dud battery when it wouldn’t charge back up beyond 75%. Especially considering they are so expensive. Thanks so much for taking the time to post this video. I’ll follow your technique and let you know if it rescues my battery🔋🤞😎

[@davidmeagher4909]

Just to update and say thank you again. I followed your method and it worked perfectly to rescue my battery. If it wasn’t for your video I wouldn’t have known how to do this. So a big thanks to you🙏😎

[@weeeves]

@@davidmeagher4909Thanks for the update. I'm glad the video helped 👍

[@davidmeagher4909]

weeeves - 👍😎 So helpful... Saved me €70 and I learned something new and useful... Respect to you🙏

[@bruceapjrgmail]

@@davidmeagher4909 so, you mean they would properly charge going forward after this fix? And the imbalance would not recur?

[@davidmeagher4909]

@@bruceapjrgmail No, you're right Bruce - after a couple of charge cycles the issue did recur. And now, a few months later, the battery won't hold a charge at all...

[@kennethbouch7796]

Why do you have to charge the lower voltage cells to match the highest one? Could you place a load of some sort on the higher cell to bring them down even to the lowest cell? Am I wrong in thinking that would achieve the same result and the actual Milwaukee charger would then charge all cells evenly.

[@ceebfwmmuas1114]

Sheesh, I was about to throw away the 9.0 battery. I will have to give this a try. TIA brother.

[@Wrenchingdaily]

Had same problem with my 9.0 HD battery. It would immediately turn green light on in the charger and led indicators were at the third level. I only had to put it in my impact gun and run it down to the second led indicator on the battery. I then put it back on the charger and it charged fully

[@Jeff-rk8hq]

To those complaining about the music maybe next time turn the volume down and maybe refrain from being critical of and or whining like your 6 to someone who literally took the time to make this for one reason and thats to help you out @weeeves so thanks man great video with concise and detailed information. Definitely super helpful to many people troubleshooting their 🪫 faulty Milwaukee packs🔋

[@mrm14_88]

Thank you so much for your help. Worked like a charm. 👍🏻

[@leslarson2642]

Seeing same problem. Clever use of a charger.

[@nitroburn72]

Helpful video--thanks. My problem is (m18, 9.0aH) that one light flashing on battery pack and it shows green light on charger. Have onpy used this battery on blower version 1 and occasionally it does this error and won't charge and charger showing green light. Each banks shows 4.45v...no banks are near 4.20. Is it overcharged? I took this pack and another and slapped their backs together one time and it showed pack had four bars. Put it back in cupboard I store them in and now it's back to the one flashing red battery light.

[@billmurray572]

My 12ah Milwaukee battery failed quickly in this manner. I restored it using this method. Thanks for how to but I wonder what’s to stop it happening again?

[@piercerounds8562]

Very nice how to to fix my 9ah battery, thanks!

[@randomname931]

how does it get into this bad state in the first place? and will it happen again post-fix?

[@luffararnesugerkuk]

Looks a very common problem with li ion packs in general, but Milwaukee ones in specific. Have got my apartment full of different brand packs waiting for this treatment, but will use a balance lead right into a Imax B6, think the few seconds it take to solder on the flying leads and plug in the connector at other side makes it worth it

[@alexanderworthen202]

Thanks for this video your descriptions helped out a lot

[@mtran66]

Thanks man. I managed to fix my 5Ah battery that would only charge to 50%. Found the low voltage cells and charged them directly

[@danadaniels4812]

When you are checking the battery voltage why do you change the polarity of your leads and repeat the voltage test?

[@softop1501]

Can I send you my battery for a repair?

[@SR71mydream]

Is this a temporary fix or will it keep happening?

[@adassociates8235]

we got exact same your battery, but on bank 3 we got 0v, will you method of charging will work(recharge) bank 3? thank you for helpful video

[@arkanoiddude]

So why did you hook up the jumper wire up to bank 2 on the positive side, and on the negative side it looks like you hooked the jumper wire up to bank 3?

[@yomomsbigpimp]

I'm trying to figure this out too

[@arkanoiddude]

@@yomomsbigpimp He ain't answering lol...hook them up to the same bank, just make sure you get the polarity correct. I've already revived 3 of my batteries since my last comment.

[@yomomsbigpimp]

@@arkanoiddude thanks man 👍👍 will try this today

[@DaveInOroValley]

I can appreciate this fix but to be truthful for your average person out there by the time they were to purchase a charger and a meter and then hope they did everything right they would be better off buying a 3rd party battery pack. EDIT: Also curious if you were to completely drain all the cells via a load placed on them if once all the cells were depleted if the charge would take again. Another EDIT: I was going to give it a try but the Torx screws seem to be glued or thread locked in place now no way to remove them at all. I was able to coax one out by really applying pressure but the other three won't budge.

[@lawrencekhoury9616]

Great video. I bought a version 2.2 charger like yours but nothing seems to happen when I insert the wires into it like you did. Checked the voltage at the wire tips and they are showing that they are well connected to the battery. Am I doing something wrong? Can it be the new version charger? Thanks for the help.

[@weeeves]

You need to make sure you have the wires connected to the proper terminals. If you see a "-" sign before the voltage on your meter, than you have the polarity reversed. If your voltage reading is greater than 4.2v, then you have the wires connected to the wrong terminals. If the voltage is below 2.5v, then the voltage may be too low for the charger to begin charging.

[@lawrencekhoury9616]

@@weeeves thank you for your prompt response. I did In fact have the polarity reversed.

[@danclancy6290]

Hello, your video has great comments so far and I would like to try this. However, I'm not certain where to find the smart charger you used. Are you able to post a link of which one I should purchase for this application? Thank you in advance!

[@edsaville9875]

Amazon has them, about $50. Opus BT - C3100

[@johnewadonis3952]

Hello, I have an M18 battery with a 5 amp on the charger that fully charges 21.2 volts and each row of cells measures 4.2 volts but the indicator light does not work and when you install the battery on the drill or saw the light of the drill lights up and does not work despite the measurements I told you about, what is the way to solve this problem, and thank you.

[@Blue04Z71]

Ok I’ve watched this about 5 times. When testing you swap the pos and neg leads around. But when you charge the black wire goes where the positive lead was when testing??? I need to charge the first bank of 3 in the pack. Closest to the charge port.

[@TranTek]

Wait for a few days to see if those Samsung 30Q sag i seen many bad cells in M18 9Ah so many M12 XC 6.0 cells turn bad, sag Milwaukee finally switch the different cells

[@adonijahtaylor547]

After you set the charger to “charge” will it just auto charge to the correct voltage or do you have to keep checking and pull off at 4.2 volts?

[@weeeves]

The charger will automatically shut off around 4.2v.

[@adonijahtaylor547]

@@weeeves thank you for the clear, concise and quick answer it really helps out as I’m in the middles of charging right now. Appreciate you!

[@pony181]

Is there another type of smart charger you can recommend? Has this type of charger worked for everyone?

[@AK99581]

Yes it works, just takes a while

[@mediatour8898]

They will send you a brand new 8.0Ah battery if you call up and tell them because this is the reason they stopped selling the 9.0AH models.

[@Steviethegr8]

Only if they’re in warranty. I’ve currently got a barely used 9.0 that’s out of warranty they won’t take.

[@Shayne6058]

I have a two 12.0 packs that won't charge, one shows about 3.7-3.8v for all banks and just flashes one red light so trying this method for that and another pack all 5 banks are down to 0.5-0.6V

[@mariobegay505]

So how did that black and decker battery hook up to a Milwaukee one?

[@weeeves]

I gutted the B&D battery and then attached a Milwaukee M18 USB charger adapter to the "+" and "-" terminals of the B&D battery.

[@michaelb2655]

My cell #3 is dead (if cell 1 starts at the end with the charging terminal). Can you tell me which terminals to hook up. I’m sure it’s simple but I’m struggling.

[@TheRoninChronicle]

I need to do this to my 12.0 battery. Which charger is everyone using?

[@LILKILLER909]

If I dont have a smart charger can I just drain power with a bulb from the banks that have more charge to even them out that way?

[@weeeves]

I wouldn't recommend discharging individual banks or cells with a light bulb without being able to regulate the discharge current (ie resistor). When you charge or discharge individual banks, you're eliminating the battery's circuit protection. If you need to discharge individual banks, then use a Smart Charger with a Discharge feature like the Opus BT-C3100. Smart chargers have the necessary circuit protection to safely charge and discharge lithium ion cells.

[@LILKILLER909]

@@weeeves damn okay, I dont have one but I have the same battery and the same problem

[@LILKILLER909]

@@weeeves I did it. I dont recomend it but I used an led flashlight to discharge the volts to the nearest 10th decimal and it worked. Took alot of patience and caution. Now all 5 banks fully charged up and got 4 bars on the led indicator. Thank you for your video.

[@christopherdelacruz84]

He recharges only directly the bank 2 and 3, but he cannot make any repair. why the2nd and 3rd bank are not charging properly what is real problem .

[@jmsmallville19]

Can somebody answer this mans questions please

[@ChristopherOrtiz22]

I don’t think these batteries have a built in balancer, eventually they might get unbalanced and this happens.

[@PLAX84]

If the battery get overheated one cell is so hot it doesn't start charging at the same time until it cools of while the rest of the battery gets a jump start on a charger therefore he charges it back up and at the end the milwauke charger will charge them as a unit if that makes sense

[@edtaber5326]

Wrong! If you read everything in the video you would notice he mentioned that two of the cells over discharged. When these cells hit low voltage they will not accept a proper charge. They have to be balanced. As previously stated they don't have a built in balance board. Most of the time this happens there is no underlying cell issues. It simply operator error pushing the packs too hard

[@GHOOGLEMALE]

my m18 battery wont run but has charge - Terminal J1 doesnt do anything (not pos or neg) whereas another M18 battery I have shows batt voltage on J1. Do you know what the prob is from your work please?

[@bradpayn1839]

It really is time to point out the real problem here... Milwaukee, and mind you, many others should have a bms as part of the control board. However that would extend the life of the batteries and cut into profits. This needs to be pointed out that the consumer is being educated, and the manufacturers need to toe the line , and do the right thing. I consider that government should have the relevent funded departments to control this bull. The manufacturers will cry that is all about safety, but it isn't,, The Tesla cars have bms for a battery of thausands of cells to allow ballanced cycling of the battery pack for 10 to 20 years,, not the pathetic 2 years that is common for our power tool industry. LUV Brad

[@JamieHarveyJr]

Milwaukee M18 batteries do have an internal BMS. And it does include cell balancing in the circuit. The circuitry can be seen during his disassembly and more detailed info can be found online of the M18 circuit. However, some intelligence such as low-voltage disconnect is located within the tool itself. This may be because Milwaukee may have different voltage cutoff specifications depending on the different motors chosen and the loads they endure for each tool application. Makita and Ryobi keep the low-voltage disconnect inside the batteries with their BMS, making them great for DIY projects or using adapters to operate with other brands of cordless tools. Connecting loads directly to Milwaukee M18 or M12 terminals without low-voltage cutoff circuitry will over-discharge and may ruin the battery. This makes the Milwaukees undesirable for PowerWheels modifications too, sadly. Most of the time when a cell imbalance occurs in the M18’s it is from a bad spot-weld, often times after a dropped battery. Possibly from a bad weld during assembly. Is this type of manual “re-balancing” is required, a very thorough inspection of the connections is usually necessary to determine the root cause of the imbalance. Milwaukee M12 batteries have no BMS inside. The only component is a thermistor for overheat/low temp protection. All battery intelligence is in the tools and chargers. One of the biggest killers of cordless batteries is from manufacturers who allow the battery to be charged to the true 100% cell capacity, where many users leave them sitting on the charger or pop them off at 100% charge and leave them sitting around for weeks or months at this level! This will accelerate degradation the most and is one contributor why these applications suffer more than say, Tesla’s (granted they have a lot going on, helping them get a TON of life from their packs). Some manufacturers limit the maximum % of charge their packs will accept (90ish % usually) which greatly improves their lifespan when exposed to fully charged long-duration storage. Ideally, storing them at about 50-60% is best, only charging them fully shortly before they are needed. However, the competitiveness in this market forces companies to use ALL of the capacity and let’s be honest, they do like selling everyone more batteries, lol. Cheers!

[@jmsmallville19]

So will doing this fix the issue or do you have to do this all the time?

[@weeeves]

I only had to do this once and it's still holding up well. This fix will not work if you have any bad cells.

[@gkhn4943]

thank you 🙏

[@kevinworley2855]

Can you do the same/similar for M12 batteries? And what would the recommended mmah rate/current be for those?

[@weeeves]

Yes, this will also work with M12 batteries. You would use the same charging current outlined in this video.

[@kevinworley2855]

Awesome, thanks...so just get to the banks by taking it out of the case or just use the pos/neg terminals on top? Or is there only one bank of 3 batteries anyway?

[@heavyequipmech2693]

Great video man! All my Milwaukee M18 batteries are still good but I'll definitely try this in the future. Currently taking apart a worx brand battery and replacing all ten of the 18650 cells. Any tips on soldering the tabs back on the new batteries? I'm decent at soldering but never tried soldering a lithium ion. Kinda scary...lol

[@toulee3551]

I'm about to do this to my 12 HD sucks this seem like a regular issue

[@debandmike3380]

Milwaukee is off my list for future battery purchases now. This is not acceptable.

[@jamesstewart2560]

They should ban music over videos 😂 it’s the absolute worse. What’s funny is people think it improves the video but it makes it unwatchable.

[@battmanbattman5308]

Seems too good to be true, but it's not!. Yes you can get the pack going again but the problem is caused by faulty self discharging cells (samsung pink 30Q are notorious for this). You will usually find that if the pack is left for a few weeks the imbalance will reoccur and again will not fully charge. The 12aH Milwaukee has Samsung 40T cells with the same issue although I notice the 12aH packs made after 2022 have different cells in them, hopefully don't suffer the same problem. Real pity because when they work they are amazing packs. I've left similar comments on the Thrifty Tool Shed youtube channel.

[@hawaiiguykailua6928]

Awesome but my battery has specialized torx screws which have a nub in the center so I can't seat my torx bit to unscrew the case. Edit, I used my spring loaded punch tool and set the tension as high as I could. Set it on the security nub and strike it about ten times and a torx wrench should grab then.

[@Therealphantomzero]

That's called security torx worth getting a set from Amazon or a kit at harbor freight if available near you

[@WiredWorkshop]

Could I charge those 2 cells with the Milwaukee charger instead?

[@weeeves]

No, that won't work. You'll need to use either a variable DC power supply or lithium ion smart charger (safest) in order to charge individual cells or banks.

[@WiredWorkshop]

@@weeeves ok awesome I’ll get the smart charger, I’m sure I’ll need it again for something else anyway

[@walterbkeen]

Personally I would suggest just dictating what your doing rather than the annoying elevator music you used here. Reference to the smart charger or a useable model would have also been helpful.

[@mediatour8898]

The iMax b6 knockoff chargers on eBay work great, I highly recommend them.

[@ForgottenGamesAndMods]

Did you just charged a milwaukee battery with B&D charger ? Does that actually work ?

[@weeeves]

No, it's a Milwaukee charger. I used a 18V B&D leaf blower to discharge the Milwaukee battery which I converted to work with Milwaukee M18 batteries 😉

[@ForgottenGamesAndMods]

@@weeeves Makes sense, thanks.

[@everythingisvibration]

Same Problem,, Hate these Batteries

[@twrcrew8852]

I never understoon WHY the hell milwaukee doesn't self-balance the batteries with the charger.. also, in my case, i am using the 5.0 with 2x each bank x4. and each cell individually measured 3.5v on my battery (this one is not unbalanced, but it says blinking dead and refuse to charge). 3.5v is far from unservicable. it's so annoying. WTF could it be?

[@ladjkaoz]

so this problem is very commun on the 9A packs... I have one with that problem. but I olso have 4A, 5A for over...6 yrs old and still keep charging just fine. I just got an 8A and 12A hope they won have this problem... btw milwaukee support sucks... went to their service center they didnt wanna try to help. they just wanted me to get a new one. and a new tool.

[@kaimanson3174]

Got two brand new batteries 2.0 from grainger. Both were completed drained in arrival. Did a jump start and both came back go life....but are not getting completely charged.

[@ladjkaoz]

@@kaimanson3174 didnt they had warranty... thats why I hate buying on line...

[@johnewadonis3952]

the drill wont run

[@CANTON76A]

Or you could discharge the full cells to the voltage of other ones, even easier, quicker and don't need fancy charger.

[@mediatour8898]

Discharge them how? You may not need a charger but you'll need something because short circuiting the batteries is definitely not good for them. Make due with what you have i suppose but if you have one of these $100+ batteries you can afford a 30$ charger. I used a cheap 18650 charger and just clamped the alligator clip down on the positive terminal and chomped the negative terminal like normal. Not the fastest charger but my other one is out on loan so it did the trick. Definitely a million ways to achieve the same goal, do whatever gets the job done safely!

[@Cory.Robson]

And how exactly would you discharge the "full cells"? I cannot think of an easy method to do this. Please help!

[@alientrade]

I'm glad everybody else liked, because I did not! If you can't talk and describe what you are doing, it is hard to follow, especially having to be a speed-reader, before the printed instructions disappear. Also, not being able to see themultimeter readings is bad. Then, what is the last 3 miinutes supposed to prove??

[@Tattooed-ig8tj]

Just buy a new one?? 😂

[@LILKILLER909]

They aren't cheep

[@Gramix666]

250€ in germany

[@DragonRyder2979]

@@Gramix666 Are you serious? That's over $400 in Australia. That's super expensive. Most expensive here is $250 Australian. Um.....fix away my friend.

[@lildamien26]

@@Gramix666 are serious

[@carsandtools]

These need to be bought while on sale. I got mine for around C$120 new in Canada (US $95). Two years down the road I also had a problem with it with the cells being charged unevenly, I fixed mine with balancer.