Problems soldering A123 battery pack

T

tapholov

1 W
Joined
Jun 17, 2008
Messages
56
Hi,

I'm looking for a solution.

I have a hundred A123 batteries, brand new from China (through E-Bay) and I can't solder them in a conventional way. The solder just doesn't stick to the (+) side. Seems O.K. on the (-) side but I stopped at my first row of 6. I have 15 to go.

I used off-the-counter lead-free solder and lead-free tinning flux. This worked before on my other Lifepo4 packs but most of them were modified project and most series were already connected with some metal ribbon which I have plenty of. The A123 are brand new.

I haven't found a battery dealer here in Montreal that wants to tab weld them. They don't even want to touch them. That's that.

I've seen a few videos on Youtube.com and it seems as if they can be soldered but there just isn't any indication as to what solder and flux is being used so they are kind of useless. Looks easy as hell but regular soldering stuff just doesn't work.

Does anyone know about this issue ? The few treads I've followed here are about whether the A123 are better than others and what not and then it goes on to somewhere else that has nothing to do with the A123 themselves.

Has anyone practical knowledge of this before I get convinced to electrocute myself trying to build a tab welder.

Thanks!
 
http://endless-sphere.com/forums/viewtopic.php?f=2&t=2633&p=220124&hilit=battery+tab+welder#p220124

Best of luck

KiM
 
Solder can stick to the aluminum. Aluminum will oxidize very quickly. Theres the rub.
I have used sand paper to rough up the surface and then coated it with an old paste flux ,so old that I can not read what the stuff is, but get the flux on the cell quickly after sanding. Then using a large tipped iron tin the end of the cell and you are good to go.
The large iron will heat the end of the cell fast and hopefully limit heat transfer into the cell. Good luck. Work fast.
A big soldering iron for stained glass work is what you want something like the size of your thumb.
 
if you check out the rcgroups forum those rc guys have a fair bit of information on soldering a123 cells.

here is a good place to start:
http://www.rcgroups.com/forums/showpost.php?p=6769001&postcount=2

some tips on this thread:
http://www.rcgroups.com/forums/showthread.php?t=1080274

i've had some success using a big iron with a heavy tip and using zinc flux and solder. you can get some from these guys:
http://www.cheapbatterypacks.com/?menu=GF132BCD6B&sid=95675

what cells do you have the new green ones?
 
See my posts on this link for how I did it: http://endless-sphere.com/forums/viewtopic.php?f=14&t=2764&p=59623&hilit=+a123+solder+pack+deep+cycle#p59623
Pack still works perfect!

Jeff K.
 
Hey Doc, You are assuming he has tabs. I don't think the China cells do...
 
jeffkay said:
Hey Doc, You are assuming he has tabs. I don't think the China cells do...
Click to expand...

So Why buying ebay china cells?... if ... after that you need to spend the saved money for buying a spot welder!! :roll: .. or try to find a way to solder in them and hope to not dammaging them..

Dewalt pack cells are ready to solder.. they have the SPOT WELDED nickel sheet that is solderable!

Doc
 
tapholov said:
I used off-the-counter lead-free solder and lead-free tinning flux.
Click to expand...


I would toss the lead-free solder, then toss the cells soldered with the lead-free solder. The temp needed to melt the lead free solder, and the increased wetting time would pretty much ensure the cells are wrecked. It's a an tough situation to solder them under ideal circumstances and not damage them internally. Doing it with lead free means the cells had quite a lot of extra heat and wetting time.
 
I agree with that LFP.

Also soldering on a pre spotwelded nickel link that is plied one time( just like with the Dewalt cells) reduce alot the heat transfer... it can only transfer thru 4 little spot weld. every of the close to 500 cells i soldered from now stay at normal temp.

Doc
 
Go here http://www.cheapbatterypacks.com/?menu=GF132BCD6B&sid=95995

Get the zinc flux and zinc solder.

Get a 100 watt solder Iron.

Practice on a few cells, you will be fine
 
Hey! a big Thanks! to you guys.

Mostly you gave me the confidence to try it again.

It would have been much easier if the batteries had had tabs to start with. Doctorbass, how can you be in Quebec city with all these events going on and still have time to work on your projects. Montrealers are getting jealous... but then... your mayor is sexier than our Adolf.

And I remembered that I had done stained glass a long time ago and I still had a big old pot of flux. Thanks! Icewrench.

I tried it and it did work a lot better. I'm not sure about keeping things cool however and the Zinc solder might get me better and easier results. I'll have to go to Addison here in Mtl since they're the best place to get that kind of stuff. I still have 14 separate packs to go.

To all of you who suggested 'cheapbatterypacks', thanks again. But (I guess is name is Mike), doesn't seem to think that the A123s are the best thing around. That's in the Q&A section at the bottom. Since I'd like this tread to discuss the A123s, what should we think of his logic ?

So, back to the pack being built.

How would I know that a battery is damaged ? So far, the packs are at 3.35V and that's the reading I get once I charge an individual battery from an individual charger and wait a bit for the voltage to settle. Is that a good indication ?

Also, while I'm at Addison, I'll look for some shrink wrap and a bigger iron. I'll bring a battery for sizing.

Here's a picture of what I've been able to do so far.

A123 first series.jpg

I guess it's tight. I can shake individual batteries and it's the bar that bends and I have done it a few times now and the solder doesn't detach from the battery. Probably shouldn't try my luck too many times.

Thanks again! It gives me hope that my dual motor currie e-bike project revives. More on soldering the pack and the e-bike itself later.

Tapholov
 
Hi forum folks!

Well, despite the zinc flux and the zinc solder, It's still hell!!!!

I've never seen a metal so reluctant to solder. The (-) side is O.K., the (+) is F.... hell!!!!, which make me think that the batteries must be indestructible.

I don't know about it all, but the few videos I've seen made it seem so easy. Anyway, I'm moving along but the batteries are taking a beating with the heat. It's so frustrating, even with a 125W iron. The solder doesn't stick, it's a miracle when it does and when it doesn't, it's more heat, more heat, more heat, even the plastic coating wants to melt away.

I'm halfway done anyway, taking it a little at a time. 8 packs done, 8 to go before they get assembled together. And I've individually charged the little packs that I'm doing and the power seems to be there, charging at 3.7V and stabilizing at 3.3V. I guess these batteries are made very strong heat wise.

Do I get jail time for abusing my A123s? It's a lot of money for having such troubles. I hope they're worth it.

I'll let you see the final stages as things get completed.

Thanks for the support.
 
When the aluminum is oxidized the solder will just form in a little ball and flick off easily.
No amount of heat will solve that.
Rough it up and put the flux on very quickly after that.
If you are lucky the solder will flow and spread nicely.
This is my idea of a big solder iron.
View attachment Big Iron.jpg
 
Thanks Ice,

But I do rough them up with a little sandpaper and yes, the solder does ball up. This doesn't happen on the (-), small side, the solder just flows nicely and I do the same thing on the bar and I join it to the batteries and it goes fine. That's half of the work.

And that's when I live with fear, confronting the other side.... (of the force).

I'll rough them up more...

Hi, hi, hi...
 
Hey tapholov,
Did you ever get the cells soldered and to stick on the (+) terminal ??
 
An Aluminium surface will form a thin layer of almost complete oxidisation in a fraction of a second of being exposed to air - even though it still looks shiny after scouring. To clean the oxidisation off and keep it that way until soldering, apply the suitable liquid flux first and then use a small wire brush to scour the surface of the cell whilst it is still coated/submerged in the flux. This maintains a barrier between the air and the raw aluminium surface until the solder is applied.

A wire brush is required because the flux is not wiped off by the scouring action like it would be with sandpaper - rather the flux pools around the bristles. I find these mini wire brushes very effective. Available cheaply from your local $2 shop or hardware store.

wb37.jpg


I achieved good results using this method combined with this solder.

42260551.jpg

http://www.newark.com/multicore-solder/629443/solder-wire-alusol-0-91mm-500g/dp/15J8243
 
That's good info on the solder, I'll have to try and get hold of some of that stuff.

However, A123 26650 tabs are not Alumium. The negative tab is nickel plated steel. The positive end has a 0.2mm section of Nickel Ni 200 laminated to the aluminium body of the cell. This can be confirmed by checking it with a magnet. The main reason it's difficult to solder is because you're not getting it hot enough, as the aluminium body acts as a great heat sink.

I've soldered quite a few A123 26650 cells and it requires the surface to be abraded, some additional flux doesn't hurt and then use a big and very hot iron. I use a 200W iron, set to 500degC and standard leaded solder. You need to work quickly and I avoid having the iron in contact with the cell for much more than 1 second at a time. I do everything in stages allowing it to cool between stages. Do not go soldering big objects between the cells. You need to put alot of heat energy into the object and it will bleed back into the cells causing excessive heating. I've used 0.2mm copper sheet and that works well. A better solution would be a coated copper sheet if you can find some as this will not corrode over time.
 
cell_man said:
That's good info on the solder, I'll have to try and get hold of some of that stuff.

However, A123 26650 tabs are not Alumium. The negative tab is nickel plated steel. The positive end has a 0.2mm section of Nickel Ni 200 laminated to the aluminium body of the cell.
Click to expand...

Thanks for this info!
Finally was able to spot weld A123 cans tonight!

https://endless-sphere.com/forums/viewtopic.php?f=14&t=110637
 
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