Charging lipo Battries - Page 1
Forum section: electronics / beginners

author: dmkmedia
author_rank: Contributor
timestamp: January 24, 2017, 08:04:05 pm
content: i have bought some on board lipo battery USB chargers i know they can charge 1 battery ok but can 1 charger , charge 2 batteries that are in series

author: cowana
author_rank: Frequent Contributor
timestamp: January 24, 2017, 08:07:14 pm
content: Assuming the batteries are at the same voltage and state of charge, that charger will be able to charge two cells inparallel(side by side with common positive and negatives, rather than stacked end-to-end).

author: bingo600
author_rank: Super Contributor
timestamp: January 24, 2017, 08:58:09 pm
content: Get these for 2 in serieshttp://www.ebay.de/itm/122216180572/Bingo

author: Rick Law
author_rank: Super Contributor
timestamp: January 24, 2017, 09:06:44 pm
content: I hate to say this, but for your safety I feel I should at least suggest... I hope you don't mind andplease don't take offense.If you do not yet know how voltage is affected when batteries are connected in series, playing around with recovered laptop batteries is not a good thing to do.I can also see from your photo that with both of your batteries, their insulation are a little damaged with patches missing and battery casing exposed. Short circuits can easily occur.When you connect batteries in series or in parallel, there may be a rush of current from the better cell to the not-as-good cell, Perhaps the "not-as-good" cell may even be a dead cell. Whether the bad one is full dead or merely "not-as-good" but not yet dead, that rush of current is not a good thing. You are playing with fire here.

author: dmkmedia
author_rank: Contributor
timestamp: January 24, 2017, 11:58:58 pm
content: i take your advise on board but i have a correct lipo battery charger and make sure that they are always charge up fully b4 any of them are used in any worki do relise there was a danger and i didn't go through with it in the end.but thanks for your concerni was just throwing a question out ... could this usb charger charge the 2 batteries..it wasnt for anything i particular i wanted to see how long 2 batteries lasted under a certain load. and was wanting to time a recharge using the charger.. but a decided not to try it.. ( better things to do)like move my tools as my wife has been asking me to do it for 3 days now

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2017, 03:27:47 am
content: Those are not LiPo batteries, they are cylindrical li-ion cells. The charging characteristics are pretty much the same as LiPo but they are much less likely to erupt into flames. I use LiPos in my RC aircraft and they can have some pretty spectacular failures if abused.

author: amyk
author_rank: Super Contributor
timestamp: January 25, 2017, 03:33:11 am
content: No, you cannot charge them in series because the charger is not a boost converter and outputs only 4.2V max.Charge them individually to full, make sure their voltages areveryclosely matched (within 1mV would be ideal), then parallel them with a few ohms resistor in between for a few minutes to allow further equalisation, and finally connect them directly together in parallel, and then you can use them like one cell of double the capacity.

author: james_s
author_rank: Super Contributor
timestamp: January 25, 2017, 03:39:32 am
content: You don't need to use a resistor. I often parallel charge my RC LiPos and as long as they are not at drastically different states of charge you can just parallel them directly and they equalize. The voltage difference is just not big enough for a large current to flow.