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3S 2200 with a bad cell Now a 2S 2200 with no bad cells.

Tritium

Amateur Extra Class K5TWM
#1
WARNING!!!! Don't try this at home unless you know what you are doing. Worse case you will burn something down with or without injuries and/or loss of property/life.:eek: You have been WARNED!

I bought a 3S 2200mAh 30C Grayson "Black" LiPo back in September. It only had about 4 flights on it and a cell went bad. It would heat up and the voltage of that cell would drop VERY quickly while the remaining 2 cells acted normally.

This evening I decided to carefully perform surgery on the battery. I carefully removed the wrappings and the bad cell was the last one connected to the black power lead. It was puffy and a check with a multimeter showed it was the bad one because the voltage was lots lower than the other 2 cells.

After carefully pealing back the kapton tape from the negative lead I simply clipped it from the bad cell and clipped the other bad cell lead from the attachment point on the middle cell (the new negative lead) then pealed the cell off of the adjacent cell slowly as not to damage the adjacent cell wrapping.

I removed the still attached piece of battery lead from the negative wire and balance wire.

I then carefully fluxed and tinned the "new" battery lead and attached the negative wire and balance wire to it.

Once certain I had a good connection I replaced the kapton tape and the other battery "bindings" i had removed.

Success, I now have a 2S 30C 2200mAh battery :applause:.

I simply have to put a large piece of heat shrink on it tomorrow to "case" it as the original was and test fly it.

The bad cell is in a safe location till it is placed in a bucket of salt water tomorrow for safe disposal.

Anyone have a old 2S balance plug you want to part with?

Thurmond
 
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colorex

Rotor Riot!
Mentor
#2
This reminds me of a thought I had some time ago. What about "flattening" a battery for special uses? As in putting the cells side by side instead of piled up. It would be easier to mount a flat battery flush and protected on a flying wing!
 

Tritium

Amateur Extra Class K5TWM
#3
It can be done. I think some "airsoft" batteries are built like that. My biggest issue was getting the bad cell to separate from the good one. They use some very good double sided tape to join them.

Thurmond
 

colorex

Rotor Riot!
Mentor
#4
It can be done. I think some "airsoft" batteries are built like that. My biggest issue was getting the bad cell to separate from the good one. They use some very good double sided tape to join them.

Thurmond
That should just be a matter of reorganizing the packs. Maybe they need a hardcase or support material to hold up better.
 

Tritium

Amateur Extra Class K5TWM
#5
Probably best to try to buy bare cells from a Chinese supplier and then assemble them in whatever fashion you want. When disassembling a multi cell pack there is always the risk of damaging the cell covering rendering it unfit for use if not downright dangerous. Lithium and water vapor = hydrogen and heat.

Thurmond
 

colorex

Rotor Riot!
Mentor
#6
Probably best to try to buy bare cells from a Chinese supplier and then assemble them in whatever fashion you want. When disassembling a multi cell pack there is always the risk of damaging the cell covering rendering it unfit for use if not downright dangerous. Lithium and water vapor = hydrogen and heat.

Thurmond
I have never disassembled a LiPo before - but with patience it shouldn't be that dangerous.
 

Tritium

Amateur Extra Class K5TWM
#7
Slow, Cautious, Methodical, No damage = no danger! IF the protective envelope surrounding an individual cell is compromised though (pinhole, tear or cut), I would definitely dispose of it right away.

Thurmond
 

colorex

Rotor Riot!
Mentor
#8
Slow, Cautious, Methodical, No damage = no danger! IF the protective envelope surrounding an individual cell is compromised though (pinhole, tear or cut), I would definitely dispose of it right away.

Thurmond
When my Bixler got wet, I made a run to unplug the battery. Apparently it got humid on the inside, but it didn't puff. Still, I put it on a stone and watched it for 10 minutes before putting it in my pocket.