"The Natural Philosopher" <a@[EMAIL PROTECTED]
> wrote in message
news:1223628702.17808.0@[EMAIL PROTECTED]
> RogerN wrote:
>> "Ed Cregger" <ecregger@[EMAIL PROTECTED]
> wrote in message
>> news:gcm39s$sdv$1@[EMAIL PROTECTED]
>>> 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
>>
>> Yeah, but you can buy packs already wired in parallel. The key should
be
>> to have them at the same voltage level before connecting the leads.
>> Another RCer told me that they connected a 4.2V cell and a 3.8V cell
and
>> only had 5A flow between them and it diminished quickly. Alghough I
>> don't recommend any connection that would cause cause more than 1C
>> current to flow into a cell, I don't think paralleling equal voltage
>> cells would be any more dangerous than charging LiPo's is. However, if
>> one pack would go bad, it may be relying on the fuses to protect the
>> other packs.
>>
>> I think I'd be better off with a multiple (4 or 5) ****t charger that
has
>> 250W power like the Hyperion 0610i does. I wouldn't have to match the
>> cell voltages before connecting. Just trying to come up with an easier
>> way to handle multiple packs without lugging around multiple chargers.
>>
>> RogerN
>>
>>
>
> Yup. The thing here is that as long as the packs are of the same
> chemistry/construction style and from the same manufacturer, *even if
the
> cells are of differing capacity* you can connect two packs in parallel
> *once you are sure they are at an equal state of charge*.
>
> If you are not sure, don't risk it.
>
> Now once they ARE in parallel, you can charge and discharge as a single
> pack.
>
> But the moment you use them independently you MUST go through the above
> procedure all over again to make sure the state of charge is the same.
>
> The reason for this is that *as long as the cells are identical
chemistry
> and construction style*, there is a completely unique relation****p
between
> voltage and charge state. So they will distribute charge and current
> correctly, and stay in balance. This is of course how large capacity
packs
> are made up: From identical cells in parallel..
>
> What is distinctly dangerous, in order of increasing insanity, is
mixing
> cells of different quality - say 15C packs versus 25C cells - from the
> same manufacturer, mixing cells from different manufacturers, or
> connecting cells in parallel when at a different state of charge.
>
> You MAY be lucky. Do you feel lucky today?
------------
If it was not you or Red Scholefield saying this, I would not have
believed
it would ever be recommended. I learned something today.
Ed Cregger
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