Rebuild battery...

Dewalt 18 volt xrp heavy duty

takes 12 "C" size rechargeables

What would be the best cells to use?

This should probably go into the Rechargeable Batteries forum, but I am sure they use sub-c's like most other rechargeable tools and that if you can get the batteries from Marrs, Inc. on Ebay, he seems to have the best prices. Failing that, the Tenergy's that are sold through would be my choice. And, oh yeah, I assume they are NiCad's, upgrade to NiMH and you should see improved performance. If you prefer a kit to essentially drop-in your battery cases, then I believe the website is sells sets that you just drop into your existing battery case, so some minimal soldering (I think) and you're battery is ready to go. They sell NiCad and NiMH drop-ins. No need to get a different charger if you upgrade to NiMH's, they are supposed to be compatible with the NiCad chargers. I am looking to do this with one of my Craftsman C3 batteries that no longer holds a charge.


Thanks for the great information.

+1 thanks for the info jonhobart.

I haven't done this (I need to, but have gotten stuck on the price of nice new cells), but have heard that if you go the home-solder route, you've got to be tidy or the battery case won't go back together nicely.

Have a look here


Maybe this thread should get sticky?

Good to know. If you buy one of the kits from batteryrebuilders (or whatever the website is) the only soldering is the wires to connect it to the battery pack. If you go the individual battery route, then yes there is a lot of soldering.

NiCads are used for a reason, they have some advantages.

Just remember, cadmium is a poison.

Like what advantages? I might have to rebuild 2 Hilti battery packs..

I have 2 Hilti also, which I would like to rebuilt...

I am no expert on battery chemistry by any stretch of the imagination, I based my opinion on what I have read about others who have successfully re-built their batteries. Just about everyone who used the NiMH's were much happier than they were with the original NiCad batteries. Those who re-built with the NiCads were happy because they did get better runtime than the OEM batteries (Edit: because the replacement NiCad batteries have better amp-hour performance than the OEM's), but not as much additional runtime as those who re-built with the NiMH's. When you compare the amp-hour ratings, the NiMH's definitely have the advantage.

What are the advantages to NiCad's over NiMH's?

Also, you rightly called me out Laughing I should have mentioned: Please recycle your old batteries, even without the container it comes in. At least in the US, Lowes does not have someone standing over the recycle center, so you could bring your old, out-of-container tool batteries there to be recycled.

Of course. In Germany, any place that sells electric stuff has to take back all cells you could imagine. They collect them and send them to recycling companies which (in theory.) recycle them. Still some people throw them in the normal trash.. :/

1) less self-discharge. If not used for long periods, you might get better runtime with their little Ah (this does not apply if your NiMHs are "low self-discharge")

2) more current (from their little Ah)

3) better performance in cold

4) last longer, no problem if discharged to 0

Well, LSD is not really a problem at this point. My OEM C3 batteries are so bad that they barely hold a charge for a week. When new, I could let them sit two months and still get use out of them, but then I used them infrequently back then. Now that I have my shop mostly together, the longest they sit is about two weeks, which should be OK with the NiMH's. Cold performance may be an issue, though, if I can't get a good heater for the shop by next winter, but I am going to start with one battery and re-build it with NiMH's to see how well it goes. If I find the performance is not as good as the hype I've read, then I'll just recycle the ones I have and get new OEM's when they go on sale.

Not disregarding what you are saying, just that I plan to experiment with my worst battery (won't even charge at this point) and see how it goes before re-building or recycling the others. I do remember that the cordless power tool manufacturers touted the NiMH batteries as an upgrade for the battery powered tools back before the LiON batteries became the "rage" (I guess that LiON prices came way down and now they are pushing the LiON batteries over the NiCad's and NiMH's).

How about a replacement for LiIon packs? One of my Protool Quadrive akku packs only shows 12.5V.. freshly charged should be 20.5 or so -> 5S2P pack imo. 18V 2.6Ah nominal.

I would stop using that pack immediately. If it really is 12.5 volts fully charged that means that some of the cells crapped out and the rest are getting overcharged.

Thanks you so Much for this information.

Woodworking Machines

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