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Old Apr 15, 2007, 02:16 AM
Luke 12:7
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USA, CA, Sunnyvale
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Help soldering a123 cells w/o tabs!!!

I had a 3s pack that I need to add 1 more cell. I have a really old weller soldering gun rated at 120 watts. I tried and tried and couldn't get it to solder. So I figured I would get a 230 watt soldering gun. Still no luck. AFter numerous cold solders I got one that I think is a good solder. I tried the solder paste, deans solder, etc.

If this cell lives even after my abuse and trying to solder it for so long than these a123 cells are awesome. At this point I'm expecting it to have a short life!

I thought the 230 watt soldering gun would be a slam dunk. Guess not. In the process I think I destroyed the radio shack 230 watt soldering gun. I had it on for quite a while. SMoke was pouring from it and the suff smelled awful. I looked at the warning on the side of the gun and it stated not to use continuously. It said 60 secs max and cool off for 4 minutes for every 1 minute used.

So question #1 - what is a good soldering iron or gun that you have soldered a123 cells w/o tabs using battery bars?

#2 is the heat output of a soldering iron better watt for watt than a gun? Is there more thermal mass?

An input would be great!
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Old Apr 15, 2007, 02:43 AM
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Letchworth, Great Britain (UK)
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I've just soldered my first A123 cells. I used a 100W iron, which I'd just bought to replace a 200+ watt gun. I sanded the ends of the cells first, and immediately applied a bit of flux paste, and then tinned them using regular resin-cored solder. 100W was plenty.

I guess the iron is best for the reason you suggest.
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Old Apr 15, 2007, 04:17 AM
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Im using 80 watt iron with hammer head, its a breeze to solder them end to end.
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Old Apr 15, 2007, 04:23 AM
know it all
Miami, Fl
Joined Nov 2003
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I solder them with a cheap weller 40w iron, no tabs and regular solder.. very easily.

Aluminum forms an oxide layer quickly and the solder will not stick to the oxide layer, the secret is friction.. rub the tip of the soldering iron quickly and firmly against the cell while applying solder, keep rubbing under the solder blob.. if you do it right the solder will stick in a normal fashion. The iron tip will scrape off the oxide layer under the molten blob of solder, once it hits clean aluminum it sticks. The molten blob of solder keeps oxygen away from the aluminum so no oxide forms.

It helps if your iron has a sharp tip to scrape with, note that aluminum oxide is transparent.

Dont apply heat for more than 2 seconds to the cell, more than that and you will damage it.. careful with that 230watt iron. Practice soldering on a piece of scrap aluminum first.

The + side of the cell has a thin disc bonded to it, you can solder easily to this disc, it just sucks heat away quickly since it is bonded to aluminum. If the thin disk falls off, you can solder directly to the aluminum using the friction method. I have had one cell with a loose soldering disc, it was not a big deal soldering directly to the aluminum.
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Old Apr 15, 2007, 04:30 AM
know it all
Miami, Fl
Joined Nov 2003
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end to end is very easy, first remove the tabs.. the problem is that the method is permanent, once soldered you will not be able to replace a cell or reconfiguer a pack.. The + end cap is an aluminum disc inset in a grooved aluminum cylinder, it will come off very easily if you put pressure on it.. it will also rotate easily thus breaking the seal.

This + end cap pops off if you overcharge the cell, it is the safety release.. goes a loud "POP". the - negative end is much tougher.

Nicads and milwaukee emolis use a steel case, strong enough that you can break the solder joint without damaging the cell.

Quote:
Originally Posted by MrMel
Im using 80 watt iron with hammer head, its a breeze to solder them end to end.
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Old Apr 15, 2007, 08:50 AM
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Thanks guys. I just have a crash while the A123 welding tap separated in air. Hope I can successfully solder it back in place. Thanks AW.
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Old Apr 15, 2007, 09:46 AM
A man with too many toys
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Those Soldering guns are useless

Get yourself a good soldering iron.


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Old Apr 15, 2007, 12:17 PM
Luke 12:7
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USA, CA, Sunnyvale
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Thanks for the tips.
I will not be soldering end to end.

I will get a good soldering iron. I found some 100watt weller soldering irons for $70 on-line. I would like to get something cheaper that would work. I"m guessing 80 watts is the minimum. Should I just get the hammerhead even though I will not be doing end to end soldering? COuld be that the hammerhead has more thermal mass so it will help more?

"Dont apply heat for more than 2 seconds " that is funny because I must have kept it on there for a minute. When I would touch the cell it woudl barely be warm. COuld be a bad soldering guns as well. In any case if the cell dies I will know why. If it lives then I'm definitely buying stock in a123!
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Old Apr 15, 2007, 12:34 PM
Permanently Banned
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tin with Harris aluminum soldering flux
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Old Apr 16, 2007, 08:13 AM
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or take them to your local Battery Store and have them spot-weld on some tabs for you....
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Old Apr 16, 2007, 08:58 AM
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Letchworth, Great Britain (UK)
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When I got my first A123s a few weeks back, I found that the discs inset into both ends seem not to be aluminum. The one at the positive end is very magnetic, and the one at the other end is slightly magnetic, whereas the bulk of the casing is not magnetic because it's aluminum.

I had no problem soldering to either end.
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Old Apr 16, 2007, 09:10 AM
Life-abstract=conformity
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Some very good info for the A-123 cells

A-123 info from SLK electronics
Quote:
The + end cap is an aluminum disc inset in a grooved aluminum cylinder, it will come off very easily if you put pressure on it.. it will also rotate easily thus breaking the seal.
Quote:
This + end cap pops off if you overcharge the cell, it is the safety release.. goes a loud "POP". the - negative end is much tougher.
The 'disc' end is -, not +
I wonder how much these cells will 'puff' before they POOF if the vent is blocked?

Some of you guys sound like an accident itching to happen.
Skies.
J
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Old Apr 16, 2007, 12:45 PM
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Quote:
Originally Posted by AirBornOne
... The 'disc' end is -, not +
I wonder how much these cells will 'puff' before they POOF if the vent is blocked? ...
I appreciate that the disc that is commonly referred to is at the -ve end. It is quite pronounced and attracts a magnet strongly.

But my A123 cells are not from a DeWalt battery pack, and don't have any tags on them. If you look closely (well, on my cells anyway) the +ve end has a larger diameter disc inset into it, flush with the surrounding aluminium. This disk is slightly magnetic -- I don't know what metal it is, but it can't be aluminium if it's magnetic, can it? -- and solders quite easily
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Old Apr 17, 2007, 07:35 AM
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I successfully solder the broken tap back to the anode with a 80W soldering iron and ordinary Pb/Tn solder. It takes 15seconds sanding and quickly put the solder and iron on it for 2-3 seconds. The solder flows like on copper and it works.

Thanks for your tips!
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Old Apr 17, 2007, 07:47 AM
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Quote:
Originally Posted by reefboy
"Dont apply heat for more than 2 seconds " that is funny because I must have kept it on there for a minute.
Better listen to suggestions. 2 seconds is good advice and it is easily possible if USING APPROPRIATE TOOLS.

Iron must be heavy, or must have huge power and very good thermal transfer. If tip is heavy, it may be cheap and needs no big power. If solder tip is thin, no power can help. Surface must reach solder temperature, and it is aluminium with extreme thermal conductivity - but there is lithium cell inside and heat kills it.
It should be quick touch of iron, covering surface. I use to immediatelly cool cell down by wet sponge. Second touch of iron solders pre-soldered wires, and again immmediate cooling. Thi have been working with NiMHs, and it does for A123.

Overheating the cell will kill it for sure - cpacity is reduced and life is very short.
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