How to Rebuild 40 Volt Battery | Power Tool Battery Fix

This 40 volt Kobalt lawn mower battery had been running down after almost 4 years of use. What originally gave me 24 minutes of power was down to only 6 minutes per charge. So I bought some new batteries at the 18650 battery store and got busy doing a rebuild of the 40 volt battery.
In this video I did use a soldering iron you can find on Amazon:
10-Piece Impact Rated 3" Security Torx Bit Set | Temper Proof, Advanced Heat Treatment, Magnetized (S2 Steel w/MnPO COATING, 3")
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Soldering Iron Kit, 80W 110V LCD Digital Soldering Welding Iron Kit with Ceramic Heater, Portable Soldering Kit with 5pcs Tips, Stand, Solder Tube, Sponge, for Metal, Jewelry, Electric, DIY
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LCD4 Rechargeable Battery Charger, Universal 18650 Battery Charger with LCD Screen Can Display Capacity, Adjustable Charging Speed, Suitable for Lithium Battery and Ni-MH/Ni-Cd AA AAA Battery
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I really did a lot of research to buy the 18650 batteries. They HAVE TO to be matching batteries to work with what I am working on - High discharge with an amp hr rating that matches my current tool battery EXACTLY . The problem of purchasing the wrong battery is a fire or explosion ( what I read online ) so I really took my time researching this.
The steps in the video are pretty straight forward. You just have to pay STRICT attention. If you watched the video, you know what I mean!
THANKS FOR WATCHING!
Also, if you are in the market for any tools, check out our Amazon store front or the links below.
Visit our amazon store front for our recommendations for tools and supplies for DIY success!
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Here is a list of some other tools we often use :
RENOVATION TOOLS - TIME & EFFORT SAVERS
DEWALT 20V MAX* Cordless Impact Driver Kit, Brushless, 1/4-inch (DCF787C2)
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DEWALT Line Laser, Self-Leveling, Cross Line, Red Beam (DW088K)
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DEWALT 20V MAX* XR Oscillating Tool Kit, 3-Speed (DCS356C1)
amzn.to/3NyVDsH
POWER TOOLS: NICE!
DEWALT Miter Saw, Single Bevel, Compound, 10-Inch, 15-Amp (DWS713)
amzn.to/36Hay3x
DEWALT 12-Inch Miter Saw, 15-Amp, Single Bevel, Compound (DWS715)
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DEWALT Table Saw for Jobsite, Compact, 8-1/4-Inch (DWE7485)
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TOOL BOX - MUST HAVES:
Gerber Gear 22-41830N EAB Pocket Knife and Money Clip, EDC Gear, Fixed Blade Knife,
Stainless Steel
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IRWIN Hammer, Fiberglass, General Purpose, Claw, 16 oz. (1954889)
amzn.to/3uABWIm
DEWALT 20V Max Cordless Drill / Driver Kit, Compact, 1/2-Inch (DCD771C2), Yellow
amzn.to/3ZBoT8c
KAIWEETS Digital Multimeter TRMS 6000 Counts Voltmeter Auto-Ranging Fast Accurately
Measures Voltage Current Amp Resistance Diodes Continuity Duty-Cycle Capacitance
Temperature for Automotive
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#40voltbattery, #fixtoolbattery, #
For more content be sure and check us out at housebarons.com/

[@Visual_Lies]

Thank you for posting this. Its something I want to dive into and you documented the process very well.

[@Housebarons]

Glad it was helpful! Hope you have fun!

[@jaredkennedy6576]

Nice. My mower will variably run 15-30 minutes depending on it's mood, although the indicator only shows one bar when it stops. Kobalt is proud of these packs, and cheap aftermarket assemblies are still $120-$150. Maybe I'll both get a replacement and rebuild the old one so I can have two batteries.

[@Housebarons]

Hey Jared, Yeah - those new batteries sure are pricy! Thx for watching!

[@chips1752]

I once did something similar, although I decided on breaking the plastic shell holding the batteries at the edges, instead of desoldering/resoldering everything since I'm usually on a time crunch. Then I covered the holes I left with electrical tape, worked like a charm although on hindsight highly unprofessional and risky.

[@Housebarons]

Hey chips, How long ago did you do this? I’m gurious about longer term performance. Thx for watching!

[@chips1752]

@@Housebarons heya there, I did that around 2y ago. It lasted a good 4months until I had to change more batteries that were failing, at which point I just replaced all batteries in the pack to avoid dealing with issues further ahead, haven't had an issue since.

[@Housebarons]

Hey chips, Very interesting! Thx for the information. That gives me an idea on what to expect! Really appreciate it!

[@jmm1000]

@@Housebarons how long did this repair work for ya?

[@shawnarmstrong6717]

Nice video, thanks for sharing. The low cells can also be re-balanced by charging them manually with something like a remote control hobby battery charger. Connect the power leads the same way you did to measure the voltage. All cells have slightly different internal resistance so they charge/discharge slightly different over time and the battery management circuitry doesn't seem to manage this wear perfectly. I have restored a few "dead" batteries this way and they work like new afterwards and have continued to do so long afterwards.

[@Housebarons]

Hey Shawn, Thanks for the info. I’ll have to give that a try! Thx for watching and sharing.

[@bscottc1]

Great job! It's always fun to beat the man. 😀 You probably already thought of it but a little tape or paper when you were prying on the tabs would have saved the short.

[@Housebarons]

Those sparks really got my attention! Thanks for the tip!

[@lothianmcadam1]

(1:24) "These are LG batteries and they're [a] very specific battery-you have to get the discharge rate and size battery. You can't mix and match!" sooo... I'm going to install into my battery pack two dissimilar unbranded Chinaseum-made knockoff 18650 batteries whose discharge rate is unknown. Still, it worked! Thanks for posting! Gotta repair my Greenworks batteries in a similar fashion.

[@Housebarons]

Hey loth.., Yes. Size and discharge rate matters. The batteries I used are identical to the originals. We’ll see how long they work. One report from a viewer did the same and got an extra season out of his repair till other original batteries died. For $5 repair - it’s worth the risk! And don’t ALL batteries come from China / Asia along with 90+ % of everything else! It would be nice if we made a little more stuff in USA! Thx for watching!

[@dusand12]

@@Housebarons I think Project Farm battery reviews have taught all of us that Chinese labels are never reality. I bet the original cells are still pretty decent and the new ones are still the limiting factor. (I know I'm 10 months late for this, but I'm doing something similar with my Kobalt battery today).

[@rottiejakeluke]

Please send me a link for the batteries used for the repair. Thank you.

[@Housebarons]

Hey, I don’t have a specific : measure your battery or match the code on the battery at 18650batterystore.com Hope that helps.

[@RonHelton]

Nice save!

[@Housebarons]

Hey Ron, Thx for watching!

[@rottiejakeluke]

Please tell me what it was that you used then GORRILA glue on/for? Thanks.

[@Housebarons]

It was just to hold a couple wires - keep them from flapping around. In place - might have used electrical tape ….

[@MrJaylassiter]

Thanks!

[@NeilBSteiner]

great...I can fix my 40v pole saw!

[@jeffrgraf]

Do you have a link of the batteries you bought? I have 2 of the exact same batteries and one barely holds any charge.

[@Housebarons]

Hey Jeff, The original cells in my Kobalt 40 battery are LGABHE41865 2500mAh batteries These 18650 batteries are - high discharge batteries ( 20 Amps continuous discharge rate ) w/ a 3.6 volt nominal voltage. 18650 = 18mm wide, 65mm tall 41865 and 18650 designations are the same I believe. I got mine from the 18650batterystore.com The Samsung have better reputation, but they were out so I used an off brand ( Eve ) There are MANY choices on the site. Make CERTAIN you do not use the wrong type/size/spec battery as they are not all the same - risk of fire or explosion from what I’ve read. Hope that helps.

[@IgorDz]

Do you think I can get a cheap used 2.0ah battery and rebuild it with batteries totaling 5.0ah? Is it gonna mess with the controllers?

[@Housebarons]

Hey Pad…, Batteries are a bit complicated. I’m a novice at this so don’t take my word as gospel. Here is how I understand it. I have a 40v 2.5ah lawn mower battery. It is comprised of (10) 3.6volt batteries connected in series to equal (36+) 40 volts at 2.5ah. I also have a 40 volt 5ah battery. That one has 2 banks of (10) 3.6v batteries. Each bank is hooked up in parallel making it a 40v battery with double the runtime (5ah). So my 2nd battery is doing what you are referring to. You just have to make sure you wire it correctly as batteries can destroy as easily as power. Do your research well before you start! Thx for watching!

[@kylenavarro9232]

I have the same batteries and one of mine won't charge and will only power each of my tools for a few seconds before they power down. My lawnmower gives 2 beeps when it powers down like it thinks the battery is dead even though it still gives 2 or 3 lights for the charge level. Could this be my issue?

[@Housebarons]

Hey Kyle, That sounds a lot like my previous battery issue. A low single cell ( or more) will interrupt battery performance while showing lights like it has more power available. You battery is only as good as it’s weakest cell. It seems like a lot of steps. But after my repair I’m more than ready to take on future repairs. I’m guessing it will get easier the more I do! Thx for watching.

[@4Lights.5Liights]

dewalt batteries? please tell; because all my repairs don't work. BMS?

[@Housebarons]

Hmm. My repairs were Kobalt . But I do have some dead Dewalt. I’ll have to give them a try and see what happens… stay tuned! Thx for watching!

[@kinglord5429]

Just bunch of what looks like c size batteries strung together. Guess lot of work inside whilst these cost so much

[@johnkelly1198]

😅They coould have made a slide out design. To me id rather buy a new battery

[@Housebarons]

Rebuilding is definitely more work but it’s saves a ton of money - especially if you have a bunch of batteries - thx for watching!

[@michaelspencer301]

Not me !! Its trash ! Don't have enough time to do what i need to do. Good video though.

[@Housebarons]

I get ya - thx!

[@douggardner9175]

Im sorry sir that was not a rebuild that was just repair just say........

[@valerianpantsulia5137]

disgusting design, shame on you guys whose design and engineering like this///////🥺