Rebuilding NICAD Battery Packs

It appears that spotwelding is the method of choice for attaching tabs to nicads. Spotwelding is normally done with, um, a spotwelder. - GWE

Bah, freeze the cells then do a quicky with a good soldering iron- usually does the deed without damaging the vent plastic on the top (+) of the cell.- did the same for a bunch of makita 9.6 stick packs/a drill master 12 v battery (2 of them) and a 9.6 black and decker. Can get the cells pretty reasonably at batteryspace.com or american scientific had some 6v-sub c packs for sale pretty cheap- but used. Pat

It's not a good idea to build NiCd packs using cells from different lots, or to mix used cells with new ones. If one of the cells is under-capacity versus the rest, it will go into reversal during discharge.

Larry Jaques wrote:

I usually buy cells with solder tabs already spot welded on them, but in a pinch I've used silver bearing conductive epoxy with excellent results. The stuff isn't cheap, but a little goes a long way, and you can store it forever in the kitchen freezer.

I've never felt good about soldering directly to battery cells except for the old LeClanche carbon-zinc ones, back in the days when most of the commercially available (greater than 1.5 volt) dry cell batteries had their individual cells connected together by bare wire soldered to the zinc cans and brass carbon rod contacts.

Happy Holidays,

Jeff

Ok, he's got a dead pack(s). If he does put them back together and he gets one cell that calls it quits, where's he out worse than he was (is?) OTOH if he manages to good a viable pack that gets him further down the road for a little sweat equity....cool. Pat

If the cells are that old they're all at end-of-life anyway. Buy all new cells and build your own pack. Batteries America will cell you sells (?).

On Sat, 11 Dec 2004 08:51:18 -0800, Grant Erwin calmly ranted:

Everybody needs a little ass, but nobody needs a smart ass. ;)

OK, for the literalists: I don't have a spot welder. What do you suggest I use?

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I've never _re_built packs, but I have soldered them together.

The best way I know is to use a hot hammerhead iron - that's a soldering iron with a bit with two working ends, so you heat both cells at once.

The bit is about 1 inch long and 1/2 inch diameter, and looks like this:

| iron | || | ___||___ | _/ \_ | |_ bit _| | \________/ |

I have turned a few from copper, it's not hard - unfortunately I don't have any now, and I can't get back to the shop before mid-Jan (long holidays!).

You really need at least a 40 watt iron, although it can be done with a smaller one. Wait for it to get hot

People who make up a lot of packs tend to put the cells in the fridge before soldering, use 60/40 tin/lead solder rather than the leadfree type (naughty, but then the cells are full of cadmium ...), and make up a frame so the cells slide easily into the right position. You heat up the ends of two cells at once, make sure they are wet with solder, remove the iron and quickly slide one cell to meet the other.

Then cover with heatshrink for mechanical strength.

Never had a problem once I figured out how to do it - and you could of course practice with the hootered cells first.

It might be worth while googling "hammerhead soldering cell" , some good links there.

Below is a post I wrote in answer to a similar question, not an immediate answer but should have some relevant tips.

However, Tim's point about reversal during discharge sounds relevant. I've always been a good boy and never tried mixing cells tho'. Perhaps you could try to find the set of cells whose capacities match best.

On Sat, 11 Dec 2004 09:51:25 -0800, "patrick mitchel" calmly ranted:

Aren't these stainless cans? I've never had good luck soldering them. I tried a few years ago and they didn't hold together worth a damn.

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On Sat, 11 Dec 2004 12:17:09 -0800, Tim Wescott calmly ranted:

I can buy new packs off Ebay for less than I can get new cells locally. But I hate to toss good cells if they can be put to use once again. Besides, I'm a tighta^H^H^H^H^H^Hfrugal person.

============================================================== Like peace and quiet? Buy a phoneless cord. http://www/diversify.com/stees.html Hilarious T-shirts online ==============================================================

I've never _re_built packs, but I have soldered them together.

The best way I know is to use a hot hammerhead iron - that's a soldering iron with a bit with two working ends, so you heat both cells at once.

The bit is about 1 inch long and 1/2 inch diameter, and looks like this:

| iron | || | ___||___ | _/ \_ | |_ bit _| | \________/ |

I have turned a few from copper, it's not hard - unfortunately I don't have any now, and I can't get back to the shop before mid-Jan (long holidays!).

You really need at least a 40 watt iron, although it can be done with a smaller one. Wait for it to get hot

People who make up a lot of packs tend to put the cells in the fridge before soldering, use 60/40 tin/lead solder rather than the leadfree type (naughty, but then the cells are full of cadmium ...), and make up a frame so the cells slide easily into the right position. You heat up the ends of two cells at once, make sure they are wet with solder, remove the iron and quickly slide one cell to meet the other.

Then cover with heatshrink for mechanical strength.

Never had a problem once I figured out how to do it - and you could of course practice with the hootered cells first.

It might be worth while googling "hammerhead soldering cell" , some good links there.

Below is a post I wrote in answer to a similar question, not an immediate answer but should have some relevant tips.

However, Tim's point about reversal during discharge sounds relevant. I've always been a good boy and never tried mixing cells tho'. Perhaps you could try to find the set of cells whose capacities match best.

I've done a bit of rebuilding myself. What I've done is to make sure that I solder to the tab left over after I've cut it free from the bad cell. This keeps the heat down on the cell itself. I also use a good hot iron and work quickly, first tinning the tab and then letting the battery get back to normal before soldering the two batteries together.

-- Why isn't there an Ozone Hole at the NORTH Pole?

I guess the point is that they're not good cells at this point -- they're just cells that haven't given up quite yet.

You might be able to find new packs on ebay at a very decent price.

On Sun, 12 Dec 2004 00:37:41 +0000, Peter Fairbrother calmly ranted:

It came through, too.

OK, I'll see what I have in real solder and give it a try on the old dead cells. I don't need the double head because I'll keep the tab on the good cell to affix to the new pack.

I have a brand new 100w stained glass iron, temp controller, and flux, but I'll probably use the Weller soldering gun.

It comes with a plastic cover and a fiber/mica shield on top. Both are reusable.

Hootered cells? I didn't know there were male and female NiCads. (See

Both packs were in the same kit originally and may even be from the same batch, so that may not be a problem.

Thanks, all. (But where are the fake spotwelder recipes?)

On Sat, 11 Dec 2004 16:50:47 -0800, Tim Wescott calmly ranted:

They're only about 2.5 years old and have had maybe 50 charges each, so my guess is that they still have life in them. Of course, I'll reglue a sneaker whose sole tried to fall off if the uppers are in good condition, too. YMMV.

On Sat, 11 Dec 2004 20:29:10 -0500, "ATP" vaguely proposed a theory ......and in reply I say!:

remove ns from my header address to reply via email

(1) You might look at NiMH cells as replacements. I know this is not in answer to your question, but you get a HEAP more energy per charge.....= longer running.

But buy only a few until you have tested them, and NEVER buy Titanium brand.

I bought 16 from bloody Ebay, and well over half got very hot and leaked when charged -by the charger supplied by the battery vendor-, and also on my other smart charger that had successfully charged many a NiMH until then. I returned them (postage starting to eat into "savings") and they came back "tested"...with the crystalline crap still showing on them!

Never again. Maybe my loss, but I have had one good, and two bad, encounters with dealers on Ebay. Enough.

I never even had a reply on the lack of the 4 x AA NiMH cells I was supposed to get with the charger.

I found a few other complaints about these Titanium brand. They claim a .1% failure rate or something. Well in that case, suck it up guys, and keep sending me new ones until I get decent bloody cells!

Oh yeah, and the rating system. This mob that sold to me had a 98.7% favourable rating. So maybe I am just the unluckiest SOB on the Net.

There's circumstantial evidence that counterfeit Sony NiMH cells are being sold on eBay. They have markedly lower capacity than the real Sony cells.

Best regards, Spehro Pefhany

Yep - what everyone is talking about a hot iron is not temperature, but the temp after putting it on a sink.

This really indicates a large or massive (physically) heater and tip. It might be a 100 or 150 watt iron. Notice this isn't the temp like 700 degree. One would expect these to reach that temp easily after warm up time.

File the tip clean - and use the heal of your shoe (inside parts to keep them looking nice) as a shield. This melted rubber (stinks a little) coats the iron so solder won't run all over the tip or the back... Have a area the size needed tinned once the rest is shielded.

Martin [ who owns a 100 Watt Black Beauty and gave his 300 watt to a friend doing gutters ]