Anyone interested in some kind of group buy for upgrading DeWalt 18v batteries?

[guiri]

Guys, I've got a bunch of 18v batteries that are old or bad or whatever and I know that you can upgrade them. However, I'm not handy and i"m not sure if I have enough smarts to do it right.

I was thinking of some kind of group buy of a few hundred cells that'll boost our battery capacity and either distribute them to the buyers or if someone is interested in modifying our packs, then pay him to do it.

I mean, I must have ten packs laying around in the house.

What say ye? Does this sound like something anyone would be interested in?
The purpose being that we either get cheaper repairs than it would cost to buy a battery or that we get a substantial power boost for the same money. ESPECIALLY considering it might very well be just one or two cells that are bad in the whole pack.

George

 

[Mr Happy]

ESPECIALLY considering it might very well be just one or two cells that are bad in the whole pack

If you rebuild a pack you have to replace ALL the cells in the pack. (Gospel of Mark, chapter 2, verse 22.)

 

[UserName]

I've tried this. I bought solder-tab sub-c nicd's, and soldered together a replacement pack. It worked for a while, had good power and runtime, but if you ran the drill down to a stall, smoke came from the solder joints.

Unless you are equipped to spotweld battery tabs to these things, it's a pointless endeavor. The solderable tabs aren't capable of carrying the amps used in a cordless tool battery pack.

 

[guiri]

Well doo doo, that sucks!

Happy, I read somewhere that it could be only one or a couple of cells that are bad. What the hell?

Now I'm depressed. All those packs sitting there doing nothing. Talk about a waste. Oh well...

Thanks guys

 

[Mr Happy]

Happy, I read somewhere that it could be only one or a couple of cells that are bad. What the hell?

Yes, it might truly be only one or two cells that are bad. But when you replace the batteries in a device you need to replace all the batteries at the same time. You should never mix new with old. This is time worn advice engraved on battery compartments everywhere.

It is a shame that some of the batteries you take out might still have some life left in them. Perhaps some other uses can be found for them in devices requiring fewer cells? Or perhaps you can match some of the older cells together into new packs by running some capacity tests on them?

 

[guiri]

Yeah, well, this coupled with the spot welding pretty much puts me out of contention.
Oh well, it was an idea..

 

[UserName]

If you ever find a way to do it, please post back here. I wanted to find a way to build my own packs for years, using higher quality cells than the OEM's put in their junk batteries. The original batteries are almost always 1300/1400 mAh cells, while the rebuilders commonly use 2100mAh cells.

Check out the cell rebuilding video here: http://www.voltmanbatteries.com/servlet/StoreFront
I tried rebuilding my own pack before I watched that video. They are exactly right about the soldered packs, at least in my experience, it worked poorly (there is the possibility my solder joints were not the best). Having the spot welder they use for that is key in this process. I don't know a way to duplicate that process with commonly available welding equipment

 

[Christoph]

We have a member that has a spot welder I believe
C

 

[guiri]

Well, I asked a friend of mine about a spot welder and here's what he said "I have the welder, but not the tongs. I usually just tack it and go on."

Not sure what that means.

For those who know, how many c cells do we need and how much are good cells at a good price, NOT considering a group buy price.

Just trying to figure if this is worth trying.

Also, if you buy them with tabs, do you need the spot welder?

Yeah, I've seen this video before.

 

[herulach]

I've always fancied a go at this instructable:
http://www.instructables.com/id/Homemade-Spot-Welder/

It looks enticingly heath robinson, yet also pretty damn cool. Jigs for spot welding RC cells are commonly available.

I don't know what configuration of what cells are in them, presumably its 15 Nimhs in series? Batteryspace do an assortment of packs in different shapes/cell sizes, and will also make up custom ones. You'd just have to integrate it into the housing then.

 

[aUtOnOmOuS_Robot]

Its dead easy to do and good solder joints can handle 10-20A, but if you're not inclined to do it you could always order a custom pack. I use http://cheapbatterypacks.com/?menu=76620DD738&sid=117363

3300mAh NiMh's are $3, 5000mAh are $5, plus they'll charge you a few bucks to assemble the pack. Just send them a pic of your battery pack so they know how to arrange the cells. Note that these are NiMh's not NiCad so you should wire a better charger into your dewalt charging base (I like the electrifly triton)

 

[guiri]

Well, the question now seems to be, is it worth dealing with?

 

[guiri]

Robot, that seems interesting...thanks