Rebuilding battery packs

[bluedog225]

I have four Milwaukee M 28 battery packs that have seen better days. I think I’ve had a couple of them for well over a decade. They all need a refresh. The new ones are running around $195 each.

I read the thread on rebuilding your own packs. It seems entirely doable with a quality spot welder and some fresh cells. But the last thing I need right now is a new project. And $250 or so for a good spot welder and yada yada yada. nah.

Long time ago, there was a guy on the Internet who would rebuild these. But I can’t find anybody currently doing that.

Does anyone know of an outfit that will rebuild these battery packs with quality cells?

thanks

 

[BillK]

I have used these guys for a couple of Snap On 14.4 volt packs. Did a good job.

Professional Battery Assembly, Rebuilding, and Repair - MTO Battery

Get high-quality service on battery rebuilds, battery repairs, and battery reconditioning on Segway, Power Tools, and specialty batteries. We specialize in batteries from Fluke, 3M, Fitel, Fujikura, Snap-On, EGO, DeWalt, Milwaukee, Akron, Trilithic, JDSU, Trimble, Sokkia, Leica, Cleco, Profoto...

www.mtobattery.com

 

[rebelranger]

I've rebuild a half dozen Ryobi battery packs and a couple random packs in the wife's vacuum, flag light, and hart 40v battery pack.

I bought a kerpu mini spot welder off Amazon which has worked great. I did buy some thinner ribbon to make the spot welds better because the cheap Amazon welder isn't the most powerful.

The best results I made was replacing the no name 3.7v lithium batteries in the wife's stick vacuum with brand name 3.8v ones. The vacuum now ***** golf balls through garden houses while lasting longer without any charging issues.

It takes me about 30min to rebuild a battery pack.

 

[walta]

I too have been tempted but the risk vs reward equation just does not work in my mind.

1 Where will you acquire first quality cells at a low enough price to make this repair viable?

2 How sure are you that you truly got quality cells that are not counterfeit or seconds and will do what is printed on the labels?

3 Will the cells you acquired be a matched set required to make a good pack?

4 Are you willing to admit that the battery packs you have built are more likely to explode and start a house fire and take that risk?

Walta

 

[bluedog225]

Getting good cells shouldn’t be a problem. There are reputable vendors. I haven’t checked pricing. Agreed on the danger. I‘d change the charging protocol to put them outside, away from flammable stuff for charging. Metal mailboxes are recommended for fire control.

 

[rebelranger]

I've had no problem getting good cells. I am not looking to build a tesla battery but a maximum 40vv battery pack.

 

[whateg01]

There are a couple of places in town here that will repack batteries. It ends up being a little less expensive than new OEM.

Why would repacked batteries be more likely to catch fire?

 

[Viper98912]

All this new battery tech, which is fantastic, yet I also don't trust it much. I also would have the nagging concern in my head over what I bought/built for a refurb. I'd just wait for a sale and buy new from Milwaukee.

 

[ronkz650]

I know it's a sin, dangerous, batteries will surely be damaged, but I still go dark side and take my life in my own hands and simply solder batteries. Either use heavy wire, like 14awg, or old solder wick. Use a file to scuff up battery terminals, put on some Flux, solder and done. Only have to hold solder iron heat for 5 seconds per connect. I'm still using AA battery packs that I soldered Eneloops in to replace the Chinesium batteries supplied 10yrs ago.

 

[Crabman]

Also had good experiences with MTO suggested by @BillK

 

[bluedog225]

I checked with MTO. They declined the M28 packs.

It’s a poorly supported Milwaukee product. Even by Milwaukee.

Not a mainstream size. Though I suspect the rebuild process is the same.

Another rebuilder also declined the job. Too bad.

 

[RTM]

I’ve got MTO queued up due to comments here, about to ship off several.

 

[Vinny]

Oh, Glad I stumbled on this! Was planning on buying some Chinese knockoffs from ebay to replace my dead Craftsman batteries. $50 to refurbish the ones I have sounds better, especially if they use quality batteries.

 

[whateg01]

Oh, Glad I stumbled on this! Was planning on buying some Chinese knockoffs from ebay to replace my dead Craftsman batteries. $50 to refurbish the ones I have sounds better, especially if they use quality batteries.

It wasn't craftsman, but somebody did a video comparing the actual capacity of knockoff batteries to OEM. Maybe ttc?

 

[silkman]

To the OP: You said you have 3 batteries which means you can canibalize one to replace the bad cells in the other two. You now have two good batteries with the same cells inside. Charging state of individual cells is important so you may need to charge cells individually

 

[peejay75]

I have used these guys for a couple of Snap On 14.4 volt packs. Did a good job.

Professional Battery Assembly, Rebuilding, and Repair - MTO Battery

Get high-quality service on battery rebuilds, battery repairs, and battery reconditioning on Segway, Power Tools, and specialty batteries. We specialize in batteries from Fluke, 3M, Fitel, Fujikura, Snap-On, EGO, DeWalt, Milwaukee, Akron, Trilithic, JDSU, Trimble, Sokkia, Leica, Cleco, Profoto...

www.mtobattery.com

(Are these rebuildable/worth it if the circuit board/controller-thingy is shot?...I have a pack that suffered water damage, I dried it out and it acted like it would accept a charge, then nada.)

 

[whateg01]

(Are these rebuildable/worth it if the circuit board/controller-thingy is shot?...I have a pack that suffered water damage, I dried it out and it acted like it would accept a charge, then nada.)

What makes you so confident that the BMS is bad? It could be that the BMS is doing its job and protecting the pack from charging because something has happened to one of the cells.

 

[bluedog225]

Interestingly, the MTO guys expressly declined to rebuild the M2 eight pack. They said it just wasn’t cost-effective with all the labor involved. We had a couple of emails and they were certain.

 

[peejay75]

What makes you so confident that the BMS is bad? It could be that the BMS is doing its job and protecting the pack from charging because something has happened to one of the cells.

(Excellent, hope-inspiring question, will revisit the pack and report back, thanks!)