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Old Jun 04, 2010, 07:19 AM
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Patriek's Avatar
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Using 2S & 3S lipos in series – any disadvantages?

I am a happy user of Zippy Flightmax lipos, but now with the current shipping problems with Hobbycity and my desperate need of batteries for my MPX Mentor I am thinking about switching to “newer generation” lipo packs possibly. Especially looking at the Hyperion packs as they can charge up to 5C.

With two Hyperion EOS 720i Net3 chargers (250W each, both fired up by their own power supply) I could charge 1 Hyperion 3S1P 5000mah and 1 Hyperion 2S1P 5000mah pack simultaneously at 4C and use them in series on my plane as a 5S2P 5000mah. Charge time will be approx 20 minutes instead of 1 hour for a 5S1P

So now I have 2 questions:

1. Are there any disadvantages to using 1 3S 5000 & 1 1 3S 5000 in series as 5S2P 5000?

2. What about the 3 cell battery and 2 cell battery charged separately and used together in series? Good idea or bad?


Thanks in advance for your sharing your knowledge


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Old Jun 04, 2010, 08:03 AM
Retired CFI Helicopter
Hughes500Bob's Avatar
Southeast PA
Joined Jun 2007
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A 3S1P 5000 and a 2S1P 5000 in series is a 5S1P 5000 pack. As long as the cells are the same in both packs I see no reason that you can not use in series and charge in series .... or charge individually and then use in series. Electrically speaking you are fine.

When charging you need to know the proper hook-up procedure for series power and series balance or you risk causing a short.



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Old Jun 04, 2010, 08:45 AM
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Thanks Bob

As far as I know - when using two Hyperion EOS 720i Net3 chargers I can hook up one one lipo to one charger including balancer connectors as one would normally do, then connect the two chargers with a "network cable" so both chargers communicate with each other and match the cells voltage (sync charging).

In that case I would not have to make a hook-up harness like in your example, right?


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Old Jun 04, 2010, 12:24 PM
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I use a 3S & 2S in series in my H9 T-34 Mentor but I also charge them as such. I never use one pack for something else over the other.

I simply need to have 2 packs in order to fit where I wanted them and so series connecting a 2S & 3S was what I needed BUT I always treat it as such a 5S pack.

You do not want their mah capacity to be to out of balance between the 2 packs.

Just be carefull where charging in series cause one of the packs needs to have one of the balance wires removed and the order the pack are connected in the charger MATTERS.
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Old Jun 04, 2010, 10:24 PM
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Texas
Joined Aug 2006
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Quote:
Originally Posted by Patriek View Post
Thanks Bob

As far as I know - when using two Hyperion EOS 720i Net3 chargers I can hook up one one lipo to one charger including balancer connectors as one would normally do, then connect the two chargers with a "network cable" so both chargers communicate with each other and match the cells voltage (sync charging).

In that case I would not have to make a hook-up harness like in your example, right?


Patriek
I do the same kind of thing with a pair of older 0610iNet chargers and sync charge a pair of 3S packs or 2S and 3S pacs. In answer to your question, no, you don't need the harness you questioned.

You hook up each balance harness to each charger like you would normally as if charging stand alone. In sync charging, the chargers see all the connected cells for balancing.
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