jari Posted March 15, 2014 Share Posted March 15, 2014 (edited) A treat for you all. , maybe... new content! "show us something new!" they cry. Well, er, yes ok. did something this morning that some might say is foolhardy, but I did it anyway. Best of all I took pictures.. and given a post is about 10x better with pictures.... I had a 3S lipo that had puffed up a little. Not sure why, think I might have run it a bit low once, and it has not been the same since. It's a 5000 mAh 40-50C turnigy. It has got worse over storage in the last few months and was looking far worse than I remember. So I decided to turn a 3S into a 2S... Have I ever done this before? no. Is it necessarily a good idea? No. Surgery began this morning. Prep: - 80W iron. check - safety glasses. check - strong cup of tea. check - sharp craft knives. check This is how the pack started. Note tape round the positive connection... don't want a short happening today. Started by removing the gorilla tape. I've been using it on the soft packs as protection along the base and ends. Screwdriver below shows where the pack should be if not swollen. The outer plastic unwraps quite easily. Started it with craft knife in the corner and then it all peeled off: To leave the near naked lipo: You can see the marks on each cell above. and much more clearly below. I don't know if this has happened before the gorilla tape. Shows how vulnerable all our soft case lipos are. Take care with yours! This close up is from the base of the lipo: Going to do this in multiple posts... next. The surgery begins. Edited March 15, 2014 by jari Quote Link to comment Share on other sites More sharing options...
jari Posted March 15, 2014 Author Share Posted March 15, 2014 Next step was to remove the outer. The cells come wrapped in a tougher plastic sheath. The ends of the battery are protected with a thin (1mm) piece of foam that is under the plastic outer. You will note the lipo bag underneath... i had the window open too. plus checked my exits. Paranoid? erm. yes. very.... Plastic sheath came off in one piece very easily: To leave me staring at the business end. At this point I went to get a second cup of tea and read the source of all knowledge, aka the internet, to check that what I was doing had been done before and was not certifiable... There might as well have been a sign saying "here be demons": Quote Link to comment Share on other sites More sharing options...
Oh How Original Posted March 15, 2014 Share Posted March 15, 2014 I was expecting to see a wrecked RC, as in you did have 3 RCs and now have 2.... Pleased to say I was wrong... Crack on with it Quote Link to comment Share on other sites More sharing options...
jari Posted March 15, 2014 Author Share Posted March 15, 2014 One cup of tea later... the desoldering begins... Made sure the iron was good and hot, and tinned properly Positive wire needs to be removed to remove the cell, and then reattached to the second cell to convert to a 2S pack: :Wire desoldered and electrical tape wrapped around the tab. I tried to be careful with shorts. Used the solder sucker to remove excess solder from the tab too. The tabs were surprisingly stiff. Took the foam end off to let the pack flex out. You can start to see how swollen the cell really was: Desoldered the second tab on the first cell. Made sure to suck excess solder off. The pack was standing up when I desoldered, and fell in this arrangement. Will support them better when I do it next time: You can see how much solder is on the cell just removed. It is literally dripping off the tab. Here is the bad cell in all glory: and compared to the remaining two cells: The swollen cell is nearly as tall as the remaining two good cells... Next? making the pack good again. Quote Link to comment Share on other sites More sharing options...
jari Posted March 15, 2014 Author Share Posted March 15, 2014 Last in series... Making the pack whole. I removed excess solder from the tab. Removed some silicon from the wire, and made sure it was tinned properly with solder. then attached to the tab. I left the blue balance lead in place. I always count up from the negative black wire, so doesn't seem important to have a red wire on this cell. I wanted to tamper as little as possible. which is quite an ironic thing to say given the pictures above... At the stage below I was able to attach to my charger and do 30 seconds of a balance charge to check it was working ok. 7.6 volts across the 2 cells and all ok. I have kept the 3S balance plug on, and the charger still recognised as a 2S. I was concerned I was going to need a 2S balance plug but apparently not: I had kept the outer plastic sheath so turned round and refitted: A bit of wrapping with packing tape, and gorilla tape to protect the ends: Lastly, I kept the sticker for the original battery and have reattached: Ta da! 2S lipo from a 3S with dead cell: The keen eyed will note I have not yet remarked it as a 2S Hope you like the pics. Lastly, please, please, please don't attempt this unless you are comfortable with what you are doing. I did this because I wanted to know how to do it, and am a compulsive tinkerer. Otherwise batteries are cheap enough to just buy a new one. I still have to dispose of the dead cell, that is outside waiting a low load to completely discharge it. Then a bucket of salt water for a week. then into the trash. 3 Quote Link to comment Share on other sites More sharing options...
vrooom Posted March 15, 2014 Share Posted March 15, 2014 are you lunatic ? 1 Quote Link to comment Share on other sites More sharing options...
cyronn Posted March 15, 2014 Share Posted March 15, 2014 Great thread, I had to do the same on my 5S pack and made it a 4S. Still works fine now been over a year since I did mine. Quote Link to comment Share on other sites More sharing options...
jari Posted March 15, 2014 Author Share Posted March 15, 2014 are you lunatic ? erm. no. My therapist tells me I am cured. and there were no pictures or proof of the last incident anyway... Part of the fun of this hobby is the tinkering, learning and investigation. and for me that means battery and electrics too. Can't see it is any more dangerous than messing around with nitro... which contains a known cancer causing agent and explosive .. and is potentially fatal or lead to blindness if swallowed. 2 Quote Link to comment Share on other sites More sharing options...
-BEZ- Posted March 16, 2014 Share Posted March 16, 2014 Well written thread fella Quote Link to comment Share on other sites More sharing options...
QRC Posted March 16, 2014 Share Posted March 16, 2014 Very good, although not for the faint hearted. Quote Link to comment Share on other sites More sharing options...
DazzaClio Posted March 16, 2014 Share Posted March 16, 2014 Done this with a couple of lipos as well. Saves wasting two good cells. Thanks. Quote Link to comment Share on other sites More sharing options...
Noj Posted March 16, 2014 Share Posted March 16, 2014 Excellent thread, can we have this pinned please Mods? Quote Link to comment Share on other sites More sharing options...
Nitroholic Posted March 16, 2014 Share Posted March 16, 2014 Provided you are careful, and take suitable precautions....it's perfectly safe to do this. If you have more than one cell puffed....bin the LiPo...but as in Jari's case...if one cell has gone bad and the rest are fine....why throw away perfectly good cells. I've done this myself with a pack that went bad, and the results are perfectly OK. Useful post with nice clear pics Quote Link to comment Share on other sites More sharing options...
RCMonkee Posted March 21, 2014 Share Posted March 21, 2014 That was great. I have repaired lipo's but never removed a cell. I have just had a cell go bad in a 3s so it is the perfect opportunity to have ago. Quote Link to comment Share on other sites More sharing options...
DeadMeatUK Posted March 22, 2014 Share Posted March 22, 2014 I've done it twice now, both successfully! Did it just the same as you with my exits marked and did it on a large baking tray so I could carry/throw it out the door if it went pear shaped. I don't know if making a guide is a good idea? Anyone savi enough to perform such task will not need a guide.... Quote Link to comment Share on other sites More sharing options...
jari Posted March 22, 2014 Author Share Posted March 22, 2014 Well it wasn't originally dine as a guide. Was done as a way I'd documenting what I did. Reader beware... Quote Link to comment Share on other sites More sharing options...
RCbutcher Posted March 28, 2014 Share Posted March 28, 2014 Its like a game of patient or whatever it is calle, but a false move ends oin fire rather than red blinking nose lol. I wouldn't dare to try this but good for those who do. He who dares... Whats this about nitro causing cancer tho ive heard it once before but ignored it. Is it the smoke out the rc only. Is it much of a threat for a smoker anyway? 1 Quote Link to comment Share on other sites More sharing options...
Rc-Bfg Posted June 20, 2015 Share Posted June 20, 2015 Looks likeni may have to try this sp i dont waist the other 4 cells Quote Link to comment Share on other sites More sharing options...
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