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Balancing series multiple Lipo packs

Old 02-08-2007, 07:04 AM
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LV_EFlyer
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Default Balancing series multiple Lipo packs

I would like to get some feedback on connecting multiple Lipo battery packs in series. I realize that it is not uncommon to connect 2 battery packs in series say : 2 5s 5000mah (18.8 volt 25c) together to accommodate large motors such as AXI 5330/24. But what of connecting 4 packs in series such as : 2 2s 5000mah (each @ 7.4v / 20c )& 2 3s 5000mah (each @ 11.1v / 20c). My concern is , even balanced packs will usually charge to capacity to different voltages for example pack 1 4.11v per cell , pack 2 4.12v per cell, pack 3 4.15 per cell, pack 4.15 per cell. My gut tells me that I should attempt to charge / discharge each pack as close to each pack as possible to keep my lipos balanced during discharge, what do you guys think.
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Old 02-08-2007, 10:07 PM
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JoshGordon
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Yes you should try to charge each pack to the same voltage. If one of the pack is lower than the other packs, you run the risk of over-discharging that pack.

Joshua Gordon
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Old 02-09-2007, 03:09 AM
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michael b
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Default serial stuff:

Isn't 2x2s Li-Po the same as a 4s pack of Li-Pos?
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Old 02-09-2007, 03:13 AM
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Default Some more?

And oh ya, how do get 18.8 volts from 5 cells, shouldn't it be 18.5? Are you looking for more push, volts, or more capacity, amps?
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Old 02-09-2007, 06:30 AM
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Larry3215
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When running packs in series its a very good idea to avoid running them to lvc.

Thats a good idea anyway, but especially important when running series packs.

My personal rule is to always leave at least 20% in my packs. I run on a timer.

Larry
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Old 02-10-2007, 09:24 AM
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Yes I should have said 18.5volts. Other than manually discharging the battery packs to get pack closely balanced , is there a way to discharge the packs using a Thunder Power 1010 charger and TP210V balancer ? I seem to recall something about grouping the battery packs with the balancer.
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Old 02-10-2007, 09:47 AM
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The 1010/210V combo will charge and balance two packs (up to 5 cells each) conected in series at the same time.

You can do 2ea 2S packs or 2ea 3S packs up to 2ea 5S packs conected in series. You can also do a 2S in series with a 5S or a 3S in series with a 4S etc etc.

No need to discharge the packs ahead of time, but its far more efficient to have them close to the same voltage/cell to start or it will take forever to balance the combined 'pack'. The 210V by itself can only discharge at a relatively low rate.

The first time I conect up a pair of packs, I charge and balance each one seperately. Then conect them in series and run them and re-charge them that way all the time.

Larry
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Old 02-10-2007, 11:11 PM
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michael b
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Originally Posted by Larry3215 View Post
The 1010/210V combo will charge and balance two packs (up to 5 cells each) conected in series at the same time.

You can do 2ea 2S packs or 2ea 3S packs up to 2ea 5S packs conected in series. You can also do a 2S in series with a 5S or a 3S in series with a 4S etc etc.

No need to discharge the packs ahead of time, but its far more efficient to have them close to the same voltage/cell to start or it will take forever to balance the combined 'pack'. The 210V by itself can only discharge at a relatively low rate.

The first time I conect up a pair of packs, I charge and balance each one seperately. Then conect them in series and run them and re-charge them that way all the time.

Larry
Agreed, charge 'em separately and wear 'em down together, then you have a "team"! The balancing takes place when you charge them as =>2s.
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Old 02-11-2007, 03:47 AM
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Originally Posted by Larry3215 View Post
The 1010/210V combo will charge and balance two packs (up to 5 cells each) conected in series at the same time.

You can do 2ea 2S packs or 2ea 3S packs up to 2ea 5S packs conected in series. You can also do a 2S in series with a 5S or a 3S in series with a 4S etc etc.

No need to discharge the packs ahead of time, but its far more efficient to have them close to the same voltage/cell to start or it will take forever to balance the combined 'pack'. The 210V by itself can only discharge at a relatively low rate.

The first time I conect up a pair of packs, I charge and balance each one seperately. Then conect them in series and run them and re-charge them that way all the time.

Larry

What of grouping the packs , I belive that I read something about looking for a ground wire that reads zero is the A group, then you label the pack for future balance charging. I don't now exactly what the process is but it seemed to be important for balancing mulitple packs together.
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