Anybody here have any experience doing this?
I have watched several videos on you tube and it seems as though it should be doable.
I have older tools that are obsolete but still work good, it's just that the batteries are tired and don't last nearly as long as they did when new.
I'm sure I could do it if I could figure out the correct replacement cells to use.
Any tips?

The smaller cells are usually welded to strips with a control board regulating output.

Some manufacturers have a kill code to make the battery as 'defective' as opposed to appearing weak or old as time passes.

Lithium Ion cells do not like heat. Welding the ends to strips does not make for a happy battery. Li-Po batteries are a bit more heat tolerant.

If you are using NiCad cells and soldering them, it should be fine.

Further research shows I would need special spot welder as regular soldering is a no-no.
I guess that tells me I will need to find a pro.

I'm having the same issues with my Milwaukee M18 batteries, primarily my 12amp.I was willing to try some of the fixes I saw on YouTube until I saw one that said the Milwaukee BMS will detect if you try to change the cells and brick the battery, this made me back off since to me a low capacity battery is better than no capacity.

If I used my battery tools for a profession and used them daily I could more easily write off the batteries loosing capacity and replacing them, but as someone who uses them occasionally as a homeowner I'm finding it very expensive and has me second guessing my commitment to battery powered tools, especially the outdoor yard tools and chainsaw. I used to do almost all my string trimmer work with just the 12amp battery, now I need 3 5amp,1 9amp and 1 12amp and those barley make it if I'm lucky.

This message has been edited. Last edited by: armored,

I bought these when I bought the wife two Ryobi sanders, they work great. We have several Ryobi batteries but they are getting old. I'm sure they are all made in China anyway. I would think they have them for the other brands as well


https://www.amazon.com/dp/B0DB...ed_asin_title_1&th=1

I suspect if you searched the inter webs you could find places selling the complete innards for the batteries, cells soldered, heat sensors and everything. All you will need to do is figure out how to open and re-seal the battery case with enough structural integrity to hold together. That's what I used to do for survey instruments (way back in the day)

I've rebuilt several li-ion battery backs including Milwaukee batteries. You don't necessarily need a spot welder, I've done battery packs with a high wattage soldering iron and plenty of flux and they are still going strong.

I would recommend using a battery with specs close to your original battery. You need to match or exceed the current draw rating of the current cells which will be probably 20A or 25A. I would use Samsung or LG or Molicell.

I would also go with pure nickel strip in the thickness necessary for the amount of current in your pack. Spot welders can be bought or made for around $20. Feel free to message if you have specific questions.

I'm a lithium battery dealer for a major battery company.

Given the nature of a lithium fire, I would no way in hell, never, and I mean ever, rebuild a tool battery myself and keep it in my home. Buy the tool battery from the manufacturer, it is built to a standard with batteries that are built to a standard.

The low-power spot welders intended for battery reconstruction are a lot easier to learn and use than traditional ferrous metal welding techniques. Not expensive either, you will save the cost of one on your first battery pack rebuild. Yes, the selection of replacement cells is important, but a quick search show wide availability of rebuild packs for popular model lines. These typically include the replacement cells themselves, connecting terminals and strips, and circuit boards, along with step-by-step instructions.

As a cost-free incentive, open up a dead or insufficient battery pack and take a look at the innards. You will see that it is very simple and easy to replicate with off-the-shelf parts.

There is also the reality that many in-battery-pack circuit boards are programmed to disallow cell charging if the batteries become depleted below some arbitrary level. Bypassing the board and partially charging the cells wth an alternative power supply will often restore them to full functionality. Many videos on YT show this procedure, often using a surplus laptop or USB charger as the power supply. As with everything involving electricity, one must exercise due care in performing procedures of this sort.

Batteries Plus rebuilt a Dewalt tool for me a decade ago.

quote:

Originally posted by MikeinNC:
Batteries Plus rebuilt a Dewalt tool for me a decade ago.

Same here, a small Dewalt screwdriver for me.

I doubt it's worth rebuilding modern 18/24 volt units. Those guys and the tools that they connect to have various intelligence built in that may make them perform poorly if you were to rebuild them.

Unlike Nicads the Lithium Ion batteries last longest if you keep them fully charged. They also do NOT like heat, so if a battery starts to feel too warm in use then take a break or change out the battery. So far I have only "bricked" one M12 battery and that was because I was clearing snow while wearing a Milwaukee "heated" jacket and ran the battery completely flat. Still pisses me off because it was a compact 3.0 Amp hour Battery and those are becoming unobtanium. BTW that heated jacket was a total waste of money, it never got warm enough for mid 20's wind chill but was such a slow drain on the batteries it was easy to "brick" a battery.

So the drill for maintaining the Milwaukee batteries. Keep them lined up on a desk or table/shelf you can dedicate for that and keep a charger on the table. That way you can press the test button on the M18 batteries to see the charge status. For the M12 batteries the only indicator is on a tool and I use an M12 Vacuum for that. If it's under 75% charge that battery. Because these batteries will self discharge when they are just sitting and lose less capacity when kept topped up. If you overheat a battery in use you will be informed of that when you go to charge it, it will trigger a charge error. Take note of how warm that battery is, it will inform you of when to change your battery is when it's starting to get too warm. For a battery that is too hot just wait until it's at room temperature and then try charging it.

Now for batteries that have been over discharged. There is a short charging cycle of roughly a minute that takes place when you first place the battery in the charger. For an over discharged battery this will trigger an error code that is "sticky for about 5 minutes". Remove the battery and if you wait for that to time out you can then insert the battery in the charger again and do another short charging cycle. Note if you don't wait long enough the error code to time out it will light up as soon as you insert the battery. After 3 or 4 of these "mini charge cycles" the battery may not set off the error code and it will charge normally. I have used this 3 times to "rescue" a bad battery and haven't observed any loss in capacity. For that M12 battery that was bricked this didn't do a thing to rescue that battery.