LiPo Battery Repair and Puncture Tests - Proceed with caution...

[GiantAntCowboy]

Hey all, I was originally going to post this in the technical/build section, but figured there may be general interest/curiosity in seeing the puncture tests and disassembled LiPos.

Disclaimer: Everything in this video is DANGEROUS, and the processes described require extreme CAUTION as well as a basic understanding of electronics, tools and soldering. I am not recommending others attempt this procedure, however since many hobbyists already do this type of repair and figured I would share my experience and tips.

FPV racing/freestyle drones specifically are very rough on batteries and most of us have at least a few damaged batteries... Instead of trashing the ones I had, each with only a single bad cell, I decided to salvage and rebuild. As part of this salvage process I decide to demonstrate what could happen if you were to accidentally puncture a LiPo with an X-acto knife... Anyway, enjoy!

If you have any questions I'm happy to discuss.
Cheers!

 

[Scotto]

Hey thanks thats a very good video. I crashed a brand new plane and battery and the shaft on the back side of the motor punctured the battery. Its a 4s and just one cell is junked. So if I were to make it a 3s all I would need is a new plug for the balance, right? Do you know what the part numbers are for those plugs?
Also should a guy worry about putting too much heat into the cell soldering right on it? Thanks.

 

[GiantAntCowboy]

Hey thanks thats a very good video. I crashed a brand new plane and battery and the shaft on the back side of the motor punctured the battery. Its a 4s and just one cell is junked. So if I were to make it a 3s all I would need is a new plug for the balance, right? Do you know what the part numbers are for those plugs?
Also should a guy worry about putting too much heat into the cell soldering right on it? Thanks.

Before I say anything, I just have to stress the Danger and Risks involved:
Accidentally bending, puncturing, or as you mentioned, overheating a LiPo cell could result in a violent fire burst and toxic smoke. In my puncture demonstration there wasn't any fire, but a quick Youtube search will show that 1-2 foot flames can blast out of these things!

It's best to work outside, or in a large open space, and the battery should not be fully charged! As always, LiPos should be monitored while charging and stored in a closed metal container. I just don't want anyone to get hurt, or cause damage to property.

Process:
Ok so, you certainly can turn a 4s into a 3s by removing the damaged cell, basically you carefully remove the damaged cell and then solder the main battery Negative (-) connection to the Negative (-) terminal on the 3rd cell. I've attached a couple diagrams for reference at the bottom.

As with any soldering, definitely avoid getting the components or connections hotter than necessary. Ensuring the wire end, battery terminal and soldering iron tip are clean and have fresh solder will make the job quick and easy.

Parts:
You can order new 3s balance plugs/leads, on Amazon for example, and to avoid unnecessary soldering you can:
- Push the included balance leads out of the new connector (lifting the tabs with the tip of an X-acto blade works well) and then
- Insert the original battery balance leads into the new connector

Questions:
- You said the motor punctured the LiPo? You just mean dented I assume?
- Do the cells currently hold different voltages? The 3 good cells should be almost identical.

Diagrams:

 

[quorneng]

Scotto
Search 'balance plugs' on ebay.
The biggest danger in any sort of rebuilding a LiPo is accidentally creating a short circuit whilst you are working on or soldering the battery terminals. You then stand a good chance of creating a LiPo fire on the workbench right in front of you.
The bigger the capacity of the LiPo the greater the consequences if things go wrong.

As I understand it when LiPo cells are put together in the factory the cells are basically inert so are safe. Once assembled the battery goes through a one time 'activation' process that alters the chemistry and puts in the initial charge.

GiantAntCowboy did say working on a 'live' LiPo is dangerous, much more so than using and charging one.
Not trying to put you off but.......