Drill Battery Pack rebuild

[BigMike]

So, i have a couple questions reguarding the battery pack in my 9 year old Dewalt 14.4v cordless drill that no longer holds a charge to drill more than 2 - 4 holes.

I have access to a few Laptop Li-Ion battery packs, but they use AA cells instead of the C cells.
1. Would this cause any problems other than shorter run time?
2. Could i put aditional AA cells in to get longer run time?
3. Can the current dewalt charger recharge Lithium Ion AA batteries?
4. Anything else i should be wary of?

Thanks,
Mike

[Joe H]

I would stay away from the lithium ion batteries. If you can find some nicad or nihm batteries you should be able to do this with no issues. The lithium ion batteries can be dangerous, they require a special charger and batteries have a pc board that regulates charging and discharging. If things get out of whack a chain reaction that results in the battery exploding can happen. Remember the exploding Dell laptops?

[MoonRise]

AA cells would most likely NOT be the cells to use, no matter what kind of chemistry they are (NiCad, Lith-ion, etc). Too much voltage sag under the high loads of a drill, and not enough amperage capacity for the high loads of a drill under load.

Yes the battery packs are (usually) rebuildable, I just had a bunch rebuilt. A chain in my area is BatteriesPlus, they rebuilt them. So far, so good.

Or if you want, you can (usually) get the (right-sized) plain cells in the appropriate chemistry for your charger and then stack-n-wrap and solder-n-weld the cells into the appropriate physical and electrical configuration.

As to your current charger being appropriate for lithium cells, most likely not. Easiest and safest rebuild option is to stick with the original cell chemistry and have the pack rebuilt.

[DSW]

I've got several rebuilt batteries for my old 14.4 Dewalts. I forget where my old boss got them from now. I've picked up one or two "generic" battery packs that fit my Dewalts from a local tool supply house at about $40 a piece or so last winter. I also watch the chain stores when the discontinue tools. I've nabbed a few tools just for the battery packs, displays/ discontinued merchandise, when they mark them down stupid cheap to blow things out before inventory.

Lately I've been upgrading everything to the 18v's from the old 14.4's. I had a tough time finding the saws to match my 14v's so ended up getting the 18v units. Now the selection on new 14v tools is slim. Want a grinder, jig saw, drywall tool and your only option is the 18v's. It's almost often cheaper to get the drill with 2 batteries and charger (especially if you can get good deals on close outs), than it is to get 2 14.4v batteries for tools that are 10+ years old. I prefer the lighter weight of the 14.4's, but since Dewalt just doesn't support the line well with new options, I'm stuck moving up to the 18V tools.

Too much of a PITA to keep two different sets of batteries charged. It's a shame my old original 14v drills would accept the 12v battery packs as well as the 14v ones. Where I used to work most of the guys had the 12v drills, I could grab any battery from their charger and slap it in my 14v drill if needed and it would run almost as good. The newer drills Dewalt "fixed" that problem and the other sizes don't fit.

[weldbead]

the dewalt tools work good, but over the years ive had 2 or 3 of the 18v batteries fry. as you say its cheaper to buy a paackaaged drill with 2 batteries than to buy 2 batteries.

[Boostinjdm]

The size you want is "sub-c" in NICAD. Nimh cells work too, but you have to buy the correct Dewalt charger. It's all yellow. I forget the model number. Rebuilding packs is easy if you have the ones that are screwed together. Cells are currently about $2-$3 each so you are looking at $24-$36 in cells for one 14.4 pack. I think the original cells in the Dewalt packs are 1400 or 1700 mAh, but I don't remember for sure. If you buy new ones, look for 2000-2400 cells to give you an increase in run time.

[BigMike]

Where would i get the batteries, do you think Radio shack might have them?

I have more time than money right now so doing a rebuild is the best thing for me. I'll take a closer look at the packs tonight so see exactly what they are and if I can easily open them.

Thanks for all the input guys. I'll forget the whole Li-Ion idea.

Mike

[MoonRise]

Where to get the cells? (a battery is a collection of cells)

Are you new to this internet thing? Search man, search.

Hmmmm, maybe here ... http://www.batterystation.com/nicads.htm

Or http://www.batteriesplus.com

and from there you can go to

http://www.batteriesplus.com/models/...es/Dewalt.aspx

Or search for 'battery' and 'dewalt' and your drill model number.

[fredf]

MoonRise: You should look for tabbed cells. If you solder directly to the cells, you may cook them! see the note on the top of the page http://www.batterystation.com/nicads.htm. tabs are spot welded on the cell.

[MoonRise]

Originally Posted by fredf

MoonRise: You should look for tabbed cells. If you solder directly to the cells, you may cook them! see the note on the top of the page http://www.batterystation.com/nicads.htm. tabs are spot welded on the cell.

pssst, Fred,

I'm not the one trying to build/rebuild a battery pack.

And for those who don't KNOW how to do it, you do have to be careful when building a battery pack. Heat is not good for batteries, and to weld (do NOT-NOT-NOT weld a battery unless you KNOW what you are doing!!!) or solder (you still have to know what you are doing to solder a battery pack) you have to apply at least some heat. Too much heat or for to long in the wrong place and you melt some internal parts of the cell and make a mess of things.

The cordless tool battery packs that I am familiar with and have seen do not use tabbed cells, except -maybe- for the 'end' cells that the wiring connects to. The other cells are stacked and soldered in the appropriate physical and electrical configuaration.

[Boostinjdm]

Actually fred, you want cells with only one tab for dewalt packs if you can find them. Due to the positioning of the cells, the tabs have to run at all different directions.

[Boostinjdm]

Hey, look what I found.... A battery ready for a rebuild. Notice the screw holes on top. If there isn't screw holes don't bother, I've tried that before.

[steve45]

There are people on Ebay that rebuild battery packs. There are a bunch of online vendors that sell the individual tabbed cells. Lithium ion cells are a little harder to come by, but you should use the type of cell that was in the battery to begin with.

[boatbuoy]

you could also try to zap your old battery ---http://www.youtube.com/watch?v=PzIlVLOH9XI

[jbman45]

I've rebuild packs for years, so here's the secret but don't broadcast it too much or you'll shorten my supply!

Most packs, dewalt, ryobi other are screwed together so just take them apart. after you try to charge the pack, take it apart and check the voltage on each battery, it should be about 1.25 volts but you'll find one or more that show zero. these are the bad guys and mark them.

yes, get some new batts but I don't buy new ones. I usually go to home depot or some other recycle place and look for their recycled batts and take home some. checking those returned you'll find some good batts, use those to replace the bad ones in your pack.

next it doesn't matter on the tab configuration, just keep the overall pattern the same. use then extra tabs you pull off or some wire which is fine....but, nicad batteries are a big heat sink so you need a 250 watt soldering iron at least. you need to quick solder the batts and better yet go to your weld shop and ask for some of their low melt solder. I buy it locally in a pak and it's really neat to join dissimiliar metals. does a clean solder joint on the batts.

also watch for sales, I bought from tractor supply about 8 brand new battery packs for their discontinued drills. paid 2 bucks a piece for the packs, who cares what they fit you take them apart and make up new dewalt bat packs.

anyway, go for it; far better than the 60 bucks a piece they want.

[steve45]

Good idea, jbman45!

[jbman45]

Also, forgot to mention in my post...for those who really don't want to do this yourself I understand you can have your pack refurbished with new batts at Battery Plus stores. Supposedly they use a slightly larger capacity (same size) battery which may even last longer than OEM stuff and understand they are a bit cheaper as well. So worth a check if you don't want to do it yourself.