rastan Posted March 29, 2022 Share Posted March 29, 2022 Hello everyone, I have an issue related to the battery.I forgot to charge the battery. I left it almost uncharged for a few months (after a ride). Now I cannot charge it. After plugging in the charger, the wheel blink red, and the charger light is green. The battery output voltage is 11V. What I have to do to solve the problem? Thanks, Rafal 1 Quote Link to comment Share on other sites More sharing options...
Miko.cz Posted March 29, 2022 Share Posted March 29, 2022 11V? I see its 84V EUC, unfortunatelly I would not be surprised if the pack is dead I would really not try to recharge them in standard way for normal time and without attention. Even some RC fan with Pro charger/discharger (with our type of batt restoration program support) would not help Im afraid. Sorry, hope Im wrong and others will help you better. Quote Link to comment Share on other sites More sharing options...
supercurio Posted March 29, 2022 Share Posted March 29, 2022 (edited) 11V could be the real battery voltage, but it is unlikely it went so low. When I capacity-tested my V10F pack, I noticed that the BMS does cut-out below a certain voltage in order to protect the cells. I think it is possible that the slow drain to keep some of the board alive and respond to the power button, discharged the pack to the BMS cut-out voltage, and that 11V is what can be measured with no-load on the disconnected BMS output. I would personally try to connect a 84V charger I can control the amperage from and set the output to 0.2-0.5A max to turn the BMS back on, then gently charge the pack again if that worked. Edited March 29, 2022 by supercurio 2 Quote Link to comment Share on other sites More sharing options...
FlyingWigs Posted March 29, 2022 Share Posted March 29, 2022 The chargers do out put a small current when green this is how the pack gets balanced, you let it sit for about 1-2 hours when green. If you really want to find out if the battery is dead, it'll have to be opened up and checked at the cell level. Not something you'd want to do without some experience. Quote Link to comment Share on other sites More sharing options...
rastan Posted March 29, 2022 Author Share Posted March 29, 2022 Thanks for your comments. I tried to charge the wheel through small resistor to decrease the charging amperage. In this case, the wheel did not appear to have a charging problem, but the battery had still uncharged (the amperage was very low). Taking into account your advice, I will try to find a charger with controlled amperage. On the other hand, I have ordered a fast charger (84 V - 5A) because I thought that maybe the cut-off charger from the battery resulted from a voltage drop. Now, I know that it is not a good idea. 2 Quote Link to comment Share on other sites More sharing options...
rastan Posted March 29, 2022 Author Share Posted March 29, 2022 I also leave the charger on the wheel for a long time without any result... I think that checking the cell voltage will be one of the next steps. 1 Quote Link to comment Share on other sites More sharing options...
meepmeepmayer Posted March 29, 2022 Share Posted March 29, 2022 Be careful, if the cells are really way under normal voltage, I believe that would permanently damage them. 2 Quote Link to comment Share on other sites More sharing options...
supercurio Posted March 29, 2022 Share Posted March 29, 2022 Seconding @meepmeepmayer, if the cells indeed went bad (and it's not only the BMS which sets itself in protection mode) then they might be transforming incoming energy into heat instead of storing it as charge. Then they can heat up enough for things to become dangerous. Once you have a working one: 84V/5A is a tad much for the V10F pack. I fast charged mine sometimes at 4.2A and later on measured about 10% degradation after 4500km+ km. More than expected. 2 Quote Link to comment Share on other sites More sharing options...
Grimm10 Posted March 30, 2022 Share Posted March 30, 2022 Maybe unplug the battery for a few days, reconnect them and try a recharge? Quote Link to comment Share on other sites More sharing options...
alcatraz Posted March 30, 2022 Share Posted March 30, 2022 How are you measuring 11V? If I remember correctly inmotion bms' don't activate the output terminals when the wheel is off. I wouldn't worry too much. Just open up the pack and measure it. If no cell group is below 2.5v then you can safely recover the pack by recharging it. You would however have to jerry rig the charger directly to the pack somehow and circumvent the bms. That could prove dangerous because you don't want to short the pack. Then after all the cells are over 3.0v the wheel can be charged normally again. Don't charge it if cells are below 2.5v. Don't charge it to 100% jerry rigged. Only do that to within normal voltages. No fast charging when operating cells near their limits. I've read of methods to reactivate dead cells by a special charging procedure but I would strongly advise against that because it won't last. The pack is designed to work as long as the cells are somewhat matched. They won't be. 1 Quote Link to comment Share on other sites More sharing options...
goatman Posted March 30, 2022 Share Posted March 30, 2022 i wouldnt be trying to charge a battery showing 11 volts without cutting the shrink wrap off and getting some voltage readings off the cells first, any p-group under 2.5v cant be trusted. heat shrink is cheap and once the pack is exposed you can do whatever is needed 1 Quote Link to comment Share on other sites More sharing options...
rastan Posted March 30, 2022 Author Share Posted March 30, 2022 In my wheel, BMS seems to give output in an unplugged battery. Tomorrow as you recommend, I will open the battery and check the voltage of all cell groups. What do I have to do when the voltage is lower than 2.5 V? Do I have try to charge low amperage for each group? Quote Link to comment Share on other sites More sharing options...
Funky Posted March 30, 2022 Share Posted March 30, 2022 (edited) 35 minutes ago, rastan said: In my wheel, BMS seems to give output in an unplugged battery. Tomorrow as you recommend, I will open the battery and check the voltage of all cell groups. What do I have to do when the voltage is lower than 2.5 V? Do I have try to charge low amperage for each group? 2.5v or under it i believe the battery is "dead" and charging it may cause fire hazard. Or some other problems.. (If i'm not wrong.) Because 3v and under counts as empty already? Edited March 30, 2022 by Funky Quote Link to comment Share on other sites More sharing options...
rastan Posted April 2, 2022 Author Share Posted April 2, 2022 I tried to charge cells (as you recommend by amperage limit 0.3-0.5 A), but the result was not good: Most cells (B1 - B4 and B5 - B13) are dead, but in the rest, the start voltage was lower than 2.5V. I think that I have to replace all batteries... Do you have any pieces of advice on the process? May I use any other batteries instead of LG MH1? 1 Quote Link to comment Share on other sites More sharing options...
alcatraz Posted April 2, 2022 Share Posted April 2, 2022 Bad luck man. To have a long lasting pack (years, not weeks), then you need to swap all the cells. They don't need to be new necessarily but matched. And if you're buying used cells, it's very hard to find matched cells unless they're new and out of the same batch. May I ask, how low were the cells that were under 2.5v? The weird thing is that it got that low. Maybe that pack has already been "repaired", or the bms is faulty. Even leaving it three years I don't see how they would just get to below 2.5v unless something else is draining them. Bad bms? Do you remember draining the pack completely on your last ride before storing it? I reused a lot of the cells in my rebuilt V8 pack, but I did so knowing it wouldn't be as new again. It actually came out slightly worse than I planned. And I took my time. I measured capacity and self discharge rates carefully for months before building. Still I need to manually balance that pack every 3-6 months depending on how much I use it. (It's because the bms stopped balancing.) So, if a new pack is too expensive to spend on the wheel, and if it works fine otherwise, you're in a similar situation as I was in. I took it apart. Kept the good cells. Measured them and made a 50% larger pack with some extra MH1 cells I bought (not new but in better condition). Got plenty of range, and I'm not afraid to ride the wheel. Had it for years since the build, and it's not deteriorated. However, you can never sell it. It's dangerous to own if you don't manually balance it every once in a while. (2 times a year). In a way it's not dangerous, because the wheel won't turn on if a group is below 3v. So a novice would just end up with a dead wheel. But still. 1 Quote Link to comment Share on other sites More sharing options...
rastan Posted April 2, 2022 Author Share Posted April 2, 2022 4 hours ago, alcatraz said: May I ask, how low were the cells that were under 2.5v? I guess pretty long (approx. six months). The color of the battery was red when I left the wheel. The problem with my wheel is that BMS does not shut down after pressing the shut down button, and the mainboard is active the whole time (I can still connect with the wheel via Bluetooth). Therefore it still spends energy from the battery. I always charged it once per month in the winter, but not during the last autumn/winter. Quote Link to comment Share on other sites More sharing options...
goatman Posted April 2, 2022 Share Posted April 2, 2022 the problem with using salvaged batteries in EUC's is if the battery gives out while riding, you crash unless there are 2 packs paralleled together, then you might be ok but not likely Quote Link to comment Share on other sites More sharing options...
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