Author Topic: Charging lipo Battries  (Read 2110 times)

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Offline dmkmediaTopic starter

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Charging lipo Battries
« on: January 24, 2017, 08:04:05 pm »
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
 

Offline cowana

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Re: Charging lipo Battries
« Reply #1 on: January 24, 2017, 08:07:14 pm »
Assuming the batteries are at the same voltage and state of charge, that charger will be able to charge two cells in parallel (side by side with common positive and negatives, rather than stacked end-to-end).
 

Offline bingo600

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Re: Charging lipo Battries
« Reply #2 on: January 24, 2017, 08:58:09 pm »
Get these for 2 in series
http://www.ebay.de/itm/122216180572

/Bingo
 

Offline Rick Law

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Re: Charging lipo Battries
« Reply #3 on: January 24, 2017, 09:06:44 pm »
I hate to say this, but for your safety I feel I should at least suggest... I hope you don't mind and please 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.
« Last Edit: January 24, 2017, 09:08:36 pm by Rick Law »
 

Offline dmkmediaTopic starter

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Re: Charging lipo Battries
« Reply #4 on: January 24, 2017, 11:58:58 pm »
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 work

i do relise there was a danger and i didn't go through with it in the end.
but thanks for your concern  :-+ i 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  :-DD

 

Offline james_s

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Re: Charging lipo Battries
« Reply #5 on: January 25, 2017, 03:27:47 am »
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.
 

Offline amyk

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Re: Charging lipo Battries
« Reply #6 on: January 25, 2017, 03:33:11 am »
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 are very closely 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.
 

Offline james_s

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Re: Charging lipo Battries
« Reply #7 on: January 25, 2017, 03:39:32 am »
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.
 


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