charging lithium ion batterys - Page 1
Forum section: electronics / general

author: m3vuv
author_rank: Super Contributor
timestamp: October 06, 2020, 02:00:32 pm
content: Hi all,im building a 16s 60v battery,the cells i have are 1500mah,they are all at 30% charge as shipped,im adding these to a 13s pack to make 16s,is it ok to charge the whole lot as one battery before i connect the bms and recharge?,just want to get the cell voltage up of them before i connect the bms so will not stress it too mutch,is this a good or bad idea?

author: maginnovision
author_rank: Super Contributor
timestamp: October 06, 2020, 05:29:15 pm
content: You can do anything you'd like but I'd make sure they're all charged to the same voltage first, charging the new cells individually. Then attach your bms and make your pack allowing you to use it normally. Also make sure the cells are ok in that configuration since I have no idea what batteries you're using.

author: nctnico
author_rank: Super Contributor
timestamp: October 06, 2020, 09:15:53 pm
content: Just charge the whole bunch but make sure the BMS has cell voltage monitoring which shuts down charging in case one of the banks reaches the maximum cell charging voltage. Bonus points if the BMS supports balancing.However I think you want to use random cells with a random BMS (from an old pack) given your other post. This is a bad idea because Li-ion cells are available in many flavours and the BMS needs to match the cell parameters. I strongly suggest to give up on this project and just buy a readily made pack.

author: Daixiwen
author_rank: Frequent Contributor
timestamp: October 07, 2020, 06:30:56 am
content: Do not charge the battery pack without a BMS unless you want to stay with your pack during the whole time and monitor yourself the voltage of each individual cell to be sure no one gets over the overcharge voltage. If you are using recycled cells and there is a slight capacity difference between the cells, even if they are balanced at the beginning the cells with lower capacity will see their voltage increase faster than the others and can reach an overcharge voltage.I would also strongly advise to make the first few charge cycles outside without any flammable material nearby until you are sure the battery is safe.If there is a difference in the state of charge between the cells, then as maginnovision suggests, charge the cells individually to the same voltage using a 1s charger, and then put all the cells in series, connect the BMS and charge the whole pack.

author: m3vuv
author_rank: Super Contributor
timestamp: October 07, 2020, 09:36:42 am
content: my 16s bms has 17 balance wires,is that right?,also how do i go about conecting this,ie what order,do i conect the balance wires to the pack then plug in the connector then the main bat -ve to the bms,or the other way around?,sorry if its a dumb question but its been a few years since i messed with these and cant remember,seem to recal tho if done in the wrong order can kill the bms,cheers in advance.also i tick notify me of replies but it never does?,any ideas?.

author: maginnovision
author_rank: Super Contributor
timestamp: October 07, 2020, 05:20:46 pm
content: One for each + and one for the overall ground. Makes 17 for 16s. I usually start at ground and work up the line. Try not to short them out

author: nancyliu
author_rank: Newbie
timestamp: October 10, 2020, 02:23:04 am
content: When charge lithium ion battery, it is necessary to charge with the suitable charger, which is good quality. Meanwhile, the battery cell is first charged with the same current to reach a stable voltage and then the voltage is certain and the current is lower and lower until reach to near zero.