"Chris Dugan" <chrisdotdugan@[EMAIL PROTECTED]
> wrote in message
news:gclf50$o4n$1@[EMAIL PROTECTED]
> On Thu, 09 Oct 2008 09:37:53 -0500, RogerN wrote:
>
>> Since LiPo's are charged at constant voltage, if you were to make a
>> harness with perhaps 1/2 Ohm between each pack, would it be possible to
>> charge/discharge multiple LiPo's in parallel?
>>
>> For example, after returning home from the field, connect all
discharged
>> batteries to a parallel adapter connected to a balancer. The adapter
>> would have small value resistors to limit the current between packs
>> since they are most likely not discharged to the same voltage. If you
>> aren't going back to the field until next week, set the charger to
>> charge to storage voltage of approx. 3.8V per cell. Then start the
>> charge before the next planned use.
>>
>> Advantages: All packs are stored at storage voltage and all packs are
>> charged to be ready before use. Use a single charger on multiple
packs.
>>
>> Need: Mating connectors for balance plugs and ~ 1/2 Ohm resistors to
>> limit current in case you throw in fully charged pack with discharged
>> packs. Fuses or other current limiting devices would be needed if you
>> might throw in a discharged pack with multiple charged packs.
>>
>> RogerN
>
> Roger,
>
> Please don't do this. You won't be able to be sure that all the packs
are
> at the same charge level before you connect them in parallel especially
> after use.
>
> The only time that it is relatively safe is to connect the packs
> immediately after charging when they are all fully charged and even then
> only do it after checking the pack voltage.
>
> A better approach would be a multiple output charger: each output
charges
> and monitors one LiPo cell but they can stay in series and all the
> charging circuitry can be fed from the same power source. That way all
> you are doing is creating copies of lower wattage charging circuits
> rather than one big charging circuit. Ok it means more work to calibrate
> and more expensive & complicated construction but it would make it
easier
> to keep the cells within tolerances and safe.
>
> --
>
> Chris
------------
I agree with Chris.
You are literally playing with fire when trying to charge packs in
parallel.
If it were that simple, you wouldn't see so many different sizes of packs
available.
Ed Cregger
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