Refurbish a damaged 4S battery - Do not try this!

N5000.4S.35.jpgI purchased a 5000mA Turnigy Nano-Teck 4S 35C, at Hobbyking for my quad-copter in build.

After a small error, i fried out one the "ground side" cell of my battery with 5 or 6 recharge cycles.
So i decided that i dont need right now a 3S battery, so i purchased a 1S Turnigy Battery bundle to repair my damaged one.


So first thing first, remove the damaged cell, was easy with my 80W iron.

3689612292?profile=originalThe new cell, fortunately was almost the same size,just a little wider and shorter.

Is a Turnigy 5000mA 40C


Cheking Battery Health - OK!


All ok, and alight, now is soldering time.


A final Check.


And the final result.

After 30min, and some tape i finally restore the battery, i spend 12€ in the end.
The battery is working, and i know that is not a long life battery, after a over discharge, the renaming 3 cells are stressed, but for a low price and only 2 battery's in my gear that worth the risk.
I have some doubts, the cover is insulator tape, and i dont know how she will do in heat. and the C rate, the original turnigy as 35C and the cell that i brought is 40C .

I hope that you enjoyed my little article.

Good flights!

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  • I have tried Tattu, you could have another choice

  • Ya it looks dangerous but I believe it is possible if the replacement cell and the damaged on are at same specs (*charging and discharge Cs). I did removed one damaged cell from a 3s lipo last time and now use it as 2s. No one ever did this before anyway all the best to you Jorge. :-D

  • Moderator

    Nice work Jorge!! I myself done some LiPo repairs..  

  • Really nice bunker! you just need a standalone wireless fire alarm and you have a full protected system.

  • Moderator

    I agree with John's note:  The batteries are more dangerous while charging than in any other situation.

    I had a cell puff, pop, and catch on fire while charging.


    - it was a 3S 500 mah, so not the biggest.  But it still spit out a flame 6 inches long!

    - I always sit with the batteries while charging, so it was easy to pick it up and toss it outside to a safe place.

    Here's my battery setup, in case anybody wants to see what I consider safe.  The first link has a photo of the battery on fire.  The second link has a picture of my awesome fireproof safe that I got out of a recycle depot.  Perfect (I hope!) for storing all batteries.

    New Battery Bunker
     Here's my new battery charging bunker.  It's a concrete block, with flats on top and bottom.  I chiseled out a slot for the wiring.  I'm ...
  • Moderator

    I had one lipo short, on the very first battery I swapped connectors on.

    Lesson learned: don't snip the positive and negative leads at the same time!

  • Jorge - Sounds like you coped a shock from the high voltage side of the laptop Switchmode PSU that you opened up, which would have been much more than 19V. You are lucky that the current was able to made such a short path through your body, as people have been killed in similar situations.
    John - You were perhaps lucky that the weakest link in the circuit was your resistive solder joint, and that the circuit could handle the current flow required to blow it so quickly.
  • Developer

    I've shorted lipos two times in my life.

    And by shorted I don't mean some huge spark when two cables accidentally touch, but the "what where you thinking when you made that connector" type of shorts.

    And both times the connectors de-soldered them self instantly before there was any real damage done to the batteries. In one instance I was even holding the connector while this happened, and ended up with soot on my fingertips but no burns. And I use 6S 5Ah batteries in different combinations almost exclusively, so we are talking about a lot of energy.

    Batteries can absolutely can be very dangerous. The most obvious being fire related if you leave the charger unsupervised. But if you are doing DIY related tasks with batteries, I think the danger are manageable. And it would require some class A stupidity to get into real trouble.

  • Jorge - 3.1V (under load) is too low. We should be stopping at 3.3V, and the cells should come back up by about 0.2V when resting. By comparison, I am usually back up to about 3.56V per cell when I am ready charge again, with a variance of no more than 0.1V between cells.
    A variance of more than 0.5V between cells is very high in my experience. However, as you can see by your fantastic graph, C2 and C3 only really start to fall off the cliff as they approach 3.3V.
  • Admin

    k , we  had  enough fun in this.  sud we fan the  flame?,  I think not.

    it was good blog no doubt abt it  irrespective about all comments.


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