808Pants Posted February 23, 2020 Share Posted February 23, 2020 Not an EUC-specific item I'm asking about, but might be of generic familiarity here. I've got a 40V pack composed of 18650 cells that no longer charges to 'five bars.' I thought when I opened it up I'd find a few low cells and perhaps be able to replace them surgically, but it seems like ALL of them are low, at around 3.75V rough average, and that's just off the charger. Do Li-ions commonly fail this way, or is this a charger problem? If the latter, anyone got a pack-troubleshooting road-map, or a generic BMS replacement or...whatever? The pack is supposed to offer 5 A-h but it's clearly not performing to spec at this point. Quote Link to comment Share on other sites More sharing options...
alcatraz Posted March 3, 2020 Share Posted March 3, 2020 (edited) It could be lithium iron phosphate chemistry (Lifepo4) which tops out at 3.7V. Ensure that it isn't before charging to 4.2V. Check the charger. 40V is not a standard voltage. Check the output with a multimeter. How many cells are there in series and parallel? Maybe you just have a faulty charger? You can discharge the pack a bit and see if you get a voltage drop when charging. That means it does in fact pull current. Bms = good, charger = bad? If not maybe it's the other way around. It's not conclusive but could indicate something. Edited March 3, 2020 by alcatraz 2 Quote Link to comment Share on other sites More sharing options...
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