Dan Robinson Posted January 29 Share Posted January 29 (edited) Somehow, I've manged to charge a 7.4v lipo, whilst simultaneously discharging a single cell of an 11.1v battery I didn't realise was connected to the charger at the same time. I didn't think that was possible on a balance charger, but there you go. Cell 3 is sitting at a little over 4v so I'm guessing it is screwed. All I can think of is to brute force it at very low amps by using crocodile clips on NIMh battery mode until I get to 3v or so, then put it back toghether and do a lroper cycle with it. The pack itself isn't puffed up too badly which is the one promising thing. Edited January 29 by Dan Robinson Link to comment Share on other sites More sharing options...
gavinkempsell Posted January 29 Share Posted January 29 Bin it (safely of course). It's only a battery. Tackle and Dan Robinson 2 Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 29 Author Share Posted January 29 (edited) Actually, I've just got my posh multimeter out to double check.... 2 cells at 8ish volts and one at 4v. Yet the charger now reports 8, 8 and 0 Hmm. Edited January 29 by Dan Robinson Link to comment Share on other sites More sharing options...
gavinkempsell Posted January 29 Share Posted January 29 2 minutes ago, Dan Robinson said: Hmm. Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 29 Author Share Posted January 29 If its being disposed of, it being done so in a totally irresponsible manner of shooting the crap out of it whilst sitting in a containment dish. 😜 Rogerborg 1 Link to comment Share on other sites More sharing options...
gavinkempsell Posted January 29 Share Posted January 29 Got my vote... do you need a recount? Link to comment Share on other sites More sharing options...
EDcase Posted January 29 Share Posted January 29 Could be worth trying your salvage idea just to see if it works. Then keep it as a backup Dan Robinson 1 Link to comment Share on other sites More sharing options...
Supporters Tackle Posted January 29 Supporters Share Posted January 29 I'd err on the side of caution, for the sake of a £10-£15 battery, is it worth the risk ? Might combust when in use in a rifle, wrecking the gat, or worse, when being charged at home, doing god knows what😱 Dan Robinson 1 Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 29 Author Share Posted January 29 I didn't think it was possible to get a lipo cell to 8v. I think my charger is just confused, because I have the 3 red wires out of the balance plug, and it is definitely 8, 8, 4 on the 3 cells. Now it's more an investigation rather than a salvage mission. Link to comment Share on other sites More sharing options...
EDcase Posted January 29 Share Posted January 29 Yeah thats strange and worth investigating. Could have ended badly... Link to comment Share on other sites More sharing options...
Sewdhull Posted January 30 Share Posted January 30 (edited) You charged a 3S lipo? And killed a cell you think? What's the voltageof the pack, not measured on the balance connector. With a meter, not the charger. Edited January 30 by Sewdhull Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 30 Author Share Posted January 30 I think what happened is that I charged a 7.4v battery, not realising there was an 11.1 still connected (it was flopped over the side of the counter). So somehow my charger has jammed 8 volts worth of angry pixies into 2 cells, whilst leaving cell 3 alone (4v). I would have expected the charger to see these two cells were at the correct voltage though or at least move angry pixies from one battery to the other. Link to comment Share on other sites More sharing options...
Supporters Rogerborg Posted January 30 Supporters Share Posted January 30 Does your charger have a storage charge setting? You could plug the mullered ones in and see if it'll balance the cells down to 3.7V or so each. In an ECPD. While filming it for Science. Dan Robinson 1 Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 30 Author Share Posted January 30 Nah, I've tried all sorts of modes with crocodile clips, leccy tape and a tin foil Sowester. The charger just yells in pain. Which the silly fecker should have done before killing one of my newst batteries. Still Saturday morning fun will be had zeroing in me SA80, and perhaps adjusting the hop on my newly repaired Speccy... I have a 7.4v where a wire snapped too close to the cells to be repaired safely. Between these two and my FLiR, it has not been a good month for be and batteries. Said FLiR battery is registering 0v which is very odd. Link to comment Share on other sites More sharing options...
Sewdhull Posted January 30 Share Posted January 30 I don't see how a lithium cell can be 8v. It may be that the charger balancing resistors or other bits are damaged and the voltages are being incorrectly reported. What's the voltage of the whole pack? Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 30 Author Share Posted January 30 8.1, 8.2, 4.08 across the balance plug. 8.17 on the Deans. Rogerborg 1 Link to comment Share on other sites More sharing options...
Sewdhull Posted January 30 Share Posted January 30 (edited) I'm assuming you are using a meter to measure those. I'm sure you can see the anomaly there. The lithium's won't be 8v. There is chemistry than prevents it. It's possible that the balance wires are screwed up because that looks like 4 + 4+ 0 and it's being measured cumulatively. The balance wires, 4 of them for 3s will have, from 0v, 4 8 12v on each wire moving from 0v. 0v to wire 1, 4v Wire 1 to wire 2 4v Wire 2 to wire 3 4v 0v to wire 3 12v. Apologises if I'm teaching you to suck eggs, but the numbers aren't right. Edited January 30 by Sewdhull Too many wires Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 30 Author Share Posted January 30 (edited) No need to apologise bud.... They're certainly weird, but I had the wires out of the balance plug, measuring across the negative in the Deans. I've got a better meter to try, but I'm wondering if two cells are somehow working in series? Balance plug is mullered now anyway 🥴 Interesting maybe, but I just dropped it accidentally, and two reds touched, generating some entertaining sparks, and a toasty battery outer shell. I wouldn't have expected that (black wire was still secure in the balance plug). Edited January 30 by Dan Robinson Link to comment Share on other sites More sharing options...
Sewdhull Posted January 30 Share Posted January 30 The red wires have a voltage relative to each other. The voltages you are measuring are cumulative. Measure between each red. The 4v red is cell 1. One of the red to red connections will be 0v Link to comment Share on other sites More sharing options...
Sewdhull Posted January 30 Share Posted January 30 Here's a better schematic Dan Robinson 1 Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 30 Author Share Posted January 30 30 minutes ago, Sewdhull said: Measure between each red Might be being daft, but are you saying put both probes across a red each? Not using the negative? Thought that would upset the meter. Sorry I'm more used to AC voltage and volt free switching circuits. Link to comment Share on other sites More sharing options...
Sewdhull Posted January 30 Share Posted January 30 Yes the reds are on the positive of each cell. So one red will be the pos of cell 1 4v with ref to 0v The reds between cell 1 POS and cell 2 pos will be across cell 2. The reds between cell 2 pos and cell 3 pos will across cell 3. You can measure cell voltages in this manner. Most of my packs have different colours for balance wires Dan Robinson 1 Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 30 Author Share Posted January 30 Yeah just done it after using up some Google Fu. One cell is totally dead. Other two have a healthy voltage. Funny how the brain works. I knew the voltages of the cells were added together. I just didn't twig it would be cullmulative on the red wires on the balance plug. Just the Deans. Not going risk pushing a charge on it. Link to comment Share on other sites More sharing options...
Sewdhull Posted January 30 Share Posted January 30 If it's dead it's damaged, chuck it. Dan Robinson 1 Link to comment Share on other sites More sharing options...
Dan Robinson Posted January 30 Author Share Posted January 30 3 minutes ago, Sewdhull said: If it's dead it's damaged, chuck it. Not before I blow the fucker up 😈 Egon_247 and AttackBunny 1 1 Link to comment Share on other sites More sharing options...
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