Repair ping battery

Grautuefel

100 W
Joined
May 11, 2016
Messages
100
Does anyone have any tips for de soldering the tabs on LiFePO pouch cells? I've been going at this all day and I'm closer to delaminating the pcb that freeing the tabs from solder.

I need to remove and replace some cells due to 1 or two bad pouches that never were good.

Using a 60w chisel tip and 4mm de soldering braid with a flux pen
image.jpeg
 
With 60 Watts you're just heating the batteries slowly.

If you want to do it properly, I recommend a 200 Watt Iron, since the large surface area of the tabs is dissipating the heat too fast.
 
Solder sucker might help. Also, on the bad cells, you could consider cutting the tabs off with a sharp blade where they come through the slot, then try to clear the slot.
 
fechter said:
Solder sucker might help. Also, on the bad cells, you could consider cutting the tabs off with a sharp blade where they come through the slot, then try to clear the slot.

I had the same thing in mind, but it looks like that'll be difficult in this case.
 
Another possible approach is to use a small screwdriver to lift the tabs up away from the board while heating. Start at one end and work your way across unit the tab is straight up. Then you might be able to solderwick along both sides enough to clear it.

With so much solder, it may be worth doing a first pass of heating and use a small wire brush or damp rag to knock off the excess solder.

If you have enough heat to melt the entire tab at once you might be able to pull on the cell while it's melted and yank it out.

The PCB part with the slots is just an assembly aid and if you destroy it, you could probably do without it or use copper wire as a replacement.
 
Might be more the size of the tip, than the iron wattage, you need a fat tip, like a stained glass iron.
 
I'll get a bigger tip and try pre-heating the whole tab with a little torch, maybe even splash out and spend the $35 for a 100w iron. Not keen on buggering up the pcb too mch as it'l be even more of a pain to put the 10p group back together. Cheers guys
 
I have repaired a few of these.
** Use a large wattage iron
** I abandoned the idea of desoldering the old tabs. It works best to use a small dremel or hack saw blade to cut out the parallel pack. This amounts to 2 cuts: one on each side to separate it from the other pack of cells. When the bad pack is removed, then it's easier to remove any good cells in the pack
!!! Cover the other terminals -- avoid shorting the battery while using a hack saw blade or other metal tools!!!!
** Then, use scrap PCB or material to configure the new tabs into a geometry that mimics the set up. Soldering is much easier than the desoldering process. Use flux.

Hope that helps.
Mark
 
Sigh

I think I am going to have to head down this destructive route. For another two hours with the 100w iron, flux and braid made no visible progress aside from one crispy finger tip.

How did you go about salvaging the good cells from the dud group?

You might not be able to see but I was very aware of shorting the contacts so I tape over everything I'm not working on.
 
https://www.ebay.com/itm/300W-SOLDERING-IRON-110-130V-HIGH-HEATING-POWER/270763843407?hash=item3f0ac85f4f:g:ceoAAOxyGb1RGTHX

This is how I did it.
 
Grautuefel said:
Jeeesus, I checked twice to make sure that wasn't a joke. That thing is beefy.

https://imgur.com/a/4FqpeXZ

No joke :D

150W was too weak for A123 and LG Chem pouch cells. So I had to use 300W.
Also the Aluminium Flux (which is way more Acidic than normal Rosin) will cause the tip to wear much faster
 
OP, how did the repair go? I have a Ping battery that has some bloated cells that need replacing, and was looking for details on how others removed the solder blobs on the pcb. 😁

I already ordered a 80w fat tip soldering iron http://a.co/d/5cE6V6J

Reading through the thread, it appears this won't have enough mass to get the solder blobs flowing quick enough for a quick and easy removal. I may have to try using a torch
 
Back
Top