Li-Po Repair

[James40]

I have a 3 cell 11.1V 1500mah li-po that the cat decided was a mouse with an electric tail.

After throwing it down two flights of stairs, the battery has lost one cell, it has a hole in the end of it and the voltave on that cell is down to 0.94v so next to nothing really.

 

Now is it possible to buy seperate cells so I can remove this dead one and solder in a new one?

It seems a shame that a brand new £35 battery is ruined after one flight.

 

Thanks in advance

[Tim Mackey]

It is.... but its often not easy as they normally use aluminium tabs and special ali solder.

I have done it in the past, but wouldnt trust it to anything much more than a cheapy foamy.

PS Hows the cat after being thrown downstairs LOL

Edited By Timbo - Administrator on 29/05/2010 11:10:05

[James40]

I soldered the cats legs back on but I think I reversed the polarity, it's now walking backwards

 

 Ok, never mind, I'll just have a 7v Li-Po and use it for running the ignition box on my Saito FG-20. Thanks anyway Timbo.

[Simon Chaddock]

James 40

If I had spent £35 on a 1500mAh 3 cell I would be very tempted to rebuild it.

 

As Timbo has said it is quite possible but with care, as you will be placing metal (a soldering iron & quite a big one at that) near to the terminals of 'live' LiPos.

 

These are rebuilds/salvage of 1500mAh 3s batteries and they were just £13 for two!

 

It is fairly simple to remove the dead cell and convert it into a 2s by re-soldering the power leads. You can even cut down the balance plug and you end up with something like this 2s.

Below however is a truly rebuilt 3s with a reclaimed cell from another battery.

It is currently giving sterling service in my Wing Dragon.

   

[Bruce Richards]

Simon are the tags on your cells aluminum and if so did you use any special solder or soldering technique?

[James40]

Simon,

Thanks for the pictures and yes, that is my plan for the damaged battery, just removing the cell and a bit of re-soldering to give me a 2 cell battery that is light weight and perfect for running the FG-20 ignition system.

 

I would repair it back to it's former glory but I have no idea who or where would sell a single Li-Po cell ?

 

The solder just seems standard Bruce, I've already de-soldered the poorly cell, it came off perfectly ok with my 30W soldering iron.

[John Bunting]

Just a week ago, a 2S 1000mA.H LiPo of mine suddenly went down to zero volts, and I found the link between the two cells had gone open-circuit. As the linking tag was aluminium, damaged, very thin and very small, I thought the chances of soldering it were pretty slim, so I cleaned it, strapped it back into contact with the bit of circuit board it connects to, using tight rubber bands round the pack, then sealed round the joint with cyano. So far it seems OK, but I'll give it a little mild knocking-about and run it at the maximum expected in-flight current before risking a model with it.

[Tim Mackey]

Hmm, not sure i would commit to flight with that one John

[John Bunting]

Thanks, Timbo. Yes, caution is the word. However, the individual cell voltages were still perfectly normal: it was just the link between them that had broken.

[Tom T]

Hi

 

I was wondering would i be able to charge a LI-PO that hasn't been charged for 7 or so months? It hasn't got any damage to it and it still has a little bit of life. Is it ok to charge or is it for the bin?

 

Cheers

Tom