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Thread: Can you charge more than one battery at a time?

  1. #1
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    Can you charge more than one battery at a time?

    I'm using 7.4v 800mah 2 cell lipo, and the sock wall charger that came with my heli. Can you charge more than one battery at a time? Do they make splitters to do this? Can this charger be used for something like that, or would I have to get a special charger?
    Thanks!

  2. #2
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    Re: Can you charge more than one battery at a time?

    Quote Originally Posted by RM3Studios
    I'm using 7.4v 800mah 2 cell lipo, and the sock wall charger that came with my heli. Can you charge more than one battery at a time? Do they make splitters to do this? Can this charger be used for something like that, or would I have to get a special charger?
    Thanks!
    With the stock charger the answer would be no. Charging a LiPo involves more than just running a current through the thing.

    It is possible to charge more than 1 pack at a time but it's not recommended. What you do is build a harness so you connect the two batteries in parallel, AND, an additional adapter for the balance plugs to convert the 2 2S plugs into a single 4S. Of course you then need a charger that is capable of charging and balancing a 4S battery which your stock charger cannot do.
    Remember, it's just a toy [car|plane|boat|helicopter|etc.]

  3. #3
    Legendary Member Frozenshade's Avatar
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    Re: Can you charge more than one battery at a time?

    You'd need to buy a special charger for that. Dual chargers are common and easy for NiMH/NiCD but a little more tricky for Lipo. There probably are cheaper units somewhere, but the only real good one I know about is made by Hyperion. It can charge and balance two lipos, but its DC so it needs at least a 30 amp power source. Runs for around $300.
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    Re: Can you charge more than one battery at a time?

    I just constructed 2 adapter cords allowing me to charge two 3S lipo batteries as one 6S with balancing. I overlooked a very important fact and I wanted to share my experience with everyone. I recently upgraded from a Blade 400 to a T-Rex 500 and wanted to charge the 3S batteries used on the Blade 400 faster (that is 2 at the same time). I puzzled over should I use parallel or series. I decided that series would work better allowing the 6S charger to balance each cell individually. I have standardized on Deans Ultra and building two male Deans in series was very easy (see attached picture). I ordered some connectors from HobbyKing in order to make the balance adapter cord. You will note in the picture that NOW I have color coded the plugs as red/black using electrical tape. It is critical that a single battery use both red or black plugs. I had not originally realized that either balance plug could not be used. I think this cost me one of my 3S batteries.

  5. #5
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    Re: Can you charge more than one battery at a time?

    I use a Triton 2 EQ 100W balance charger (http://www3.towerhobbies.com/cgi-bin...&I=LXVZA8&P=ML) to regularly charge up to 8 2S 500-1000 mAh packs simultaneously. This is called parallel charging. I use this charge board + a couple other parallel adapters I plug into it (go to H o b b y k i n g.com and search for "charging board"). The board by itself is designed for only up to 6 batteries at once, so I added a couple parallel harnesses to get 8. However, YOU MUST KNOW WHAT YOU ARE DOING OR PARALLEL CHARGING IS DANGEROUS. For example, if you plug a 2S battery in with a 3S battery, the 2S battery will be destroyed and catch fire if you leave it there.

    A couple things to know about parallel charging:
    1) ONLY USE THE SAME # OF CELL BATTERIES, ***NO**** EXCEPTIONS. Ex: 2S with 2S, 3S with 3S, etc.
    2) Use batteries of similar capacities. Ex: 500-1000 mah batteries together, or 1300-1800 mah batteries together, but *not* a 500 mah battery with a 2000 mah battery.
    3) Use batteries with similar states of charge (how much they are charged/discharged). Ex: do NOT put a 1/2 full or 3/4 full battery in parallel with an empty battery. All batteries must be at similar discharge state.
    4) Use batteries of similar ages. Ex: advisable not to put a new battery with a 2 year old battery, but not critical as long as the batteries are within similar capacities.
    5) Always plug in the *main* plug first on ALL batteries, *then* plug in all the balance plugs. Also, it is good to *wait several minutes* AFTER plugging in the main battery leads into the parallel charge board BEFORE plugging in the balance plugs. This prevents high currents from flowing through the balance plugs as the batteries equalize based on their varying voltages upon plugging them in. The main plugs can take more current. This is also the reason you want to use batteries of similar states of charge/discharge.
    6) To determine the charge rate when charging in parallel (assuming the standard 1C charge rate), ADD all of the battery capacities together, then use that value as the charge current. Ex: parallel charging three 3S 1300 mAh (1.3Ah) LiPo's with two 3S 1000 mAh (1Ah) Lipo's would mean that you should set your charger on the 3 cell LiPo setting at a charge rate of (3 x 1.3) + (2 x 1) = 5.9A. Therefore, in this scenario, a charge rate of 5.9A corresponds to a 1C charge rate, and the charger will consider all of those batteries in parallel to be a *single* 5900 mAh 3S Lipo.


    Google for more info on "parallel charging" of LiPo packs. Note: this method is NOT recommended for Nihm or NiCad cells, as it may cause them to catch fire, though for Lipos it works great.

    Also see these links:

    http://ascforithobbies.com/index.php...ing-board.html (read description at bottom)

    ****http://www.rcgroups.com/forums/showthread.php?t=932319

    ***** http://sites.google.com/site/tjinguy...allel-charging

    *****http://www.rchelicopterfun.com/paral...-charging.html

    And for additional general LiPo info, here's an extensive article I wrote, titled
    "LiPo Batteries, ESC’s, and Prop Selection":

    http://www.rcdiscuss.com/showthread....ensive-Article
    Last edited by panther3001; 06-14-2012 at 07:34 PM. Reason: added more details about charge currents and waiting between plugging in main leads and balance leads

  6. #6
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    Update: For those interested in parallel charging: New Parallel charging article now posted here: http://electricrcaircraftguru.blogsp...teries_22.html
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