Repairing a zippy flightmax 8000

[Seya]

Hey guys,

Firstly

I'm not a novice but by no means a guru with batteries.

In May of this year I purchased a flightmax 8000 for my custom built mid drive bike. It worked fine at first. But then I noticed my charger ( hobby people tazer charger ) which is probably a shit box started overcharging this number 1 cell in the 6S. Always ended up dangerously high, 4.2 volts plus but never felt any heat off the pack. So I tried deep discharging and rebalancing but same problem. I always use the balance leads and attach via my custom built harness. So in august I noticed the charger started throwing this alarm ( connection break ) so I called hobby people and they said there's a broken connection inside the battery.

My question is can anyone advise my on the possibility of repairing the broken cell connection myself. And also if the battery has been sitting at half charge for 3 months is that an unrectifiable problem?

Thanks!

 

[NeilP]

The hardest part of repairing any of these pouch cell type batteries is soldering to the tabs.
One tab is usually made of some metal that just wont accept solder...not standard solder anyway.

if the pack is useless as it is, you have nothing to loose.
First start by very cutting and peeling off all the shrink wrap, sticky tape and padding from the top of the battery.

The you can get to see all the cell tabs, and where the balance wires main wire connections etc. from there it is easy enough to see if any of the connections between cells or the balance wires have become unsoldered.

Does the pack show voltage across the main terminals?

 

[dogman dan]

You might have a simple loose wire on the balance plug now. That's an easy fix. But you seem to definitely have a cell with low capacity, and it will keep on overcharging all the time. It's gotta go!

If your bad cell is the last one on the row, then you can fix it into a 5s pack by simply moving the big wire. Unsoldering it and resoldering it to a new position is fairly easy with a large solder iron, one with a chunky tip that holds lots of heat. You can leave the old cell there unless it's punctured, just no longer connected except at one terminal.

Stripping off and replacing a cell is still fairly easy if it's the last one on either end. One in the middle is a bitch.

Sometimes the easiest route, is to strip out two cells. Then you can buy a 2s pack, and just plug in the connections to make it into a 4s + 2s = 6s pack.

 

[jonescg]

The hardest part of repairing any of these pouch cell type batteries is soldering to the tabs.
One tab is usually made of some metal that just wont accept solder...not standard solder anyway.

The positive tab is aluminium when it leaves the pouch. On some packs they spotweld the positive to the copper negative directly - I have noticed this on the 2s Nanotech packs. Most packs use copper tabs spotwelded to the aluminium tab, and these copper tabs are nickel plated. If you have a nickel plated copper tab, scuff it up a bit so you can see shiny copper, and solder that little tab with a big hot iron, 80 W or more. It tins up nicely.

If the pack has been spotwelded together completely, you will be SOL. Nothing sticks to aluminium.

 

[Ypedal]

I'd start by tripple checking the pin connections between the pack and charger ( extension pigtails are notorious for wearing out and giving the " connection break " error on chargers ) ..

If all that checks out, and you absolutely must and are willing to dig into a pack...

http://ypedal.com/Lipo/repair.htm

for reference only.. i take no responsibility if you blow yourself up !

 

[Punx0r]

Get a cell checker IMO and rule out the charger

 

[eq1]

I realize this is an old topic, but it's one of the many yet more pointed threads I've come across looking for some info...

I'm trying to separate the cells in a Zippy Flightmax 4S 8Ah Lipo pack - and it's not as easy as I thought it might be. The tabs look like they might be crimped and possibly spot welded or soldered together. And the solder itself seems really difficult to melt... I could barely get the solder to melt with a microtorch enough to pull off the balance leads... I tried heating with that torch (longer than I would have liked to) and pulling the tabs apart - but still no success. Is this a futile exercise?

I mainly want to get the cells apart because I only want to test one of them, rather than 4 of them, at a time... I can do this now, but I'd rather have the cells apart and stored away while I'm testing just the one...

Here's some picts of the tabs:

 

[Ykick]

They're making it harder for us. For those in your picture (crimp/spot weld) I just cut em. Hammerhead soldering tip in 60W iron is what I use. Don't need as much heat as you do mass.

 

[eq1]

Yeah, I was thinking cutting might be the only way, yet one of the tabs is really short, there's really nothing to cut - just a blob of solder. So if I ever wanted to reuse that cell I'd still have to figure out a way to get that solder blob melted off... Are you saying that you (can) use the hammerhead tip with 60W iron for getting them apart, too, or are you just saying you use that setup for soldering?

Oh, also, are you confirming that the connection is indeed a crimp and a weld? I can't tell what it is; it has obviously been crimped, but maybe that's also a crimp made by a welding tool of some sort...

 

[Ykick]

Hammerhead tip for soldering/desoldering only. I really dunno what that junction is? I think a little of both weld/crimp but just a guess.

 

[eq1]

fyi, here's a couple more picts of the zippy tabs, one zoomed to 10x. It looks like it must be a crimping-spot welding tool. The close up shows the remains of what was an aluminum positive tab attached to the nickel negative tab of the adjacent cell. This particular connection was kind of misaligned - only part of the aluminum tab actually got crimped and, I'm thinking, welded. You can see where the alleged crimp-spot weld tool hit the nickel tab rather than the aluminum tab -- and you might be able to make out what looks like heat/burn marks to me, those dark little diamond-shaped spots, left on the nickel tab...