TommyC Posted November 8 Share Posted November 8 I’ve got an almost new 4s battery that has puffed up on one cell. I’m thinking I can turn it in to a 3s but I’ve never soldered directly onto lipos before. Am I right in thinking you need some kind of special solder and/or flux to be able to this? I’m fairly confident with soldering, but perhaps not that quick. Do I need to worry about putting too much heat into the lipo? Should I discharge to 3.0v? Quote Link to comment Share on other sites More sharing options...
wombat Posted November 8 Share Posted November 8 Bearing in mind that you would also have to solder on a 3s balance lead, and wondering about the state of the remaining 3 cells i would err on the side of caution and dispose of it. If its almost new could you claim on warranty ? Quote Link to comment Share on other sites More sharing options...
TommyC Posted November 8 Author Share Posted November 8 Corally would not honour the warranty, as its over 30 days since purchase but thankfully modelsport were good and are sending me a replacement. Just seems a waste to chuck this when it’s only had 2-3 cycles. Was thinking I can just remove the extra balance lead but leave the 4 pin plug on. My charger will still only recognise it as 3s. It’s also capable of showing me resistance when charging so I can check it’s all good when I charge it. I can then 3d print a new case for it. 1 Quote Link to comment Share on other sites More sharing options...
locky Posted November 8 Share Posted November 8 I've removed a dead cell from a 4s and use it as 3s. Just used normal solder and cover exposed connections to prevent shorts. 1 Quote Link to comment Share on other sites More sharing options...
TommyC Posted November 9 Author Share Posted November 9 (edited) Well the lipo is now in a bucket of salt water in the garden! I got it apart just fine but as usual I made it more complicated than it needed to be. I wanted to flip the new negative tab over and solder to the other side of it. It doesn’t work. A little more research told me I need aluminium specific liquid flux. Unfortunately I got the tab a bit hot and it started to melt the glue a little around the edge of the lipo so I’m not taking the risk. Good practice for next time though. Edited November 9 by TommyC 1 Quote Link to comment Share on other sites More sharing options...
Stormbringer Posted November 9 Share Posted November 9 I can solder and do it reasonably well but i wouldnt attempt what you did mate Quote Link to comment Share on other sites More sharing options...
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