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Old Nov 11, 2013, 09:59 AM
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United States, KY, Louisville
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Running batteries in series..... Your thoughts

When running your high powered EDfs with two batteries in series, is it best to always keep those same batteries together for every flight or do you think mixing and matching is better?

For example: I have 4 4s batteries numbered 1-4 respectively. I always fly numbers 1 and 2 together and numbers 3 and 4 together. Each flight is always different.
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Old Nov 11, 2013, 12:06 PM
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United States, CO, Denver
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I wouldn't know why it would matter. Each and every cell is different and can perform differently. Lipo has no memory so everytime you charge and discharge is a new set of variables.

Keeping them in pairs would make it easier to keep track of things though.
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Old Nov 11, 2013, 12:16 PM
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I always thought lipos in a way had memories. I was thinking that if a lipo packs IR started to get to high, it would tax the other lipo making it work harder. I figured if I was mixing that higher IR pack between two other packs wouldn't that just shorten the life of those other two packs? I figured that it would be better to doom one pack instead of two or more. What does everyone else do? Do they dedicate their packs in pairs or switch them around?
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Old Nov 11, 2013, 01:59 PM
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I usually run 7S & 8S consisting of 2 3S & 2 4S packs so I'm constantly swapping them around depending which jet I'm flying. I bought all 4 at the same time, same brand same c rating and mah similar ir reading. Never an issue.

I think one pack or cell with high ir will suffer much worse then the other cells and will puff/overheat before the good ones.
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Old Nov 11, 2013, 02:44 PM
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I would run a lipo battery monitor on each battery balance lead during flights. When any cell hits 3.3V (or whatever you decide the cutoff to be) you will hear the beeping.
You will always know when a pack is getting weak before it causes a complete battery failure.
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Old Nov 11, 2013, 09:25 PM
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upland CA
Joined Dec 2004
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You can mix and match any combo of lipo as long as the volts match when you plug them in. Your limit will always be the worst pac..I have run pacs of diffrent capacity and it works as long as you dont go past the low volts on any pac.If you dont pay close attention the low pac will fail
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Old Nov 11, 2013, 09:42 PM
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u cant mix IR ratings, you cant mix C ratings, and running various mah size packs is very risky.
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Old Nov 11, 2013, 09:50 PM
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Kevin Cox's Avatar
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I always keep a pair a pair. Easier to keep track of charging and cycles.
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Old Nov 11, 2013, 10:28 PM
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I always use a timer, so I don't wait for the LVC to warn me to LAND! AHHHH! LAND!!!! LOL. As for what I do, I don't mix Mah Packs. That's a receipe for disaster in my book. I always keep mine in pairs, I was just curious as to what others do.

I'm not following the comment on not being able to mix different IR packs. Why not? Every pack has different IR. Maybe I'm not understanding.
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Old Nov 12, 2013, 01:18 AM
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Australia, NSW, Williamtown RAAF
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I use a synchronising charger - Hyperion Duo, 2 batts at the same time - all cells charged to the same voltage so at least they start off even. Mine are kept as pairs, but probably more out of superstition than any good reason on my part, and I time all flights.
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Old Nov 12, 2013, 02:13 AM
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United States, PA, Erie
Joined Sep 2008
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All of my 8s setups use pairs of 4s packs, they are numbered, and I do tend to keep pairs together. However, when I fly a 4s powered plane, I'll take whichever is handy and use it. Even if I use say 4 packs individually, they all even out on the charger and I am back to where I was. I just try not to use any one pack more than the others, and do keep an eye on the IRs from time to time.

Jay
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Old Nov 12, 2013, 03:05 AM
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United Kingdom, England, Southampton
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My charger can charge, and balance (displaying all 14 cells present voltages as it goes along), two batteries in any combination up to 14S in series as if they were one. So I keep them together. Don't even have to remove the joining link when I take them out of the plane. But I do number them. But it would do unmatched 'sets' just as well.
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Old Nov 12, 2013, 07:20 AM
Watt me worry?
Madmax1965's Avatar
Florida
Joined Mar 2006
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Skylineflyer:
I always thought lipos in a way had memories.

Nope................lipos do not have memories.
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Old Nov 12, 2013, 07:48 AM
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Canada, ON, Burlington
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Quote:
Originally Posted by Madmax1965 View Post
Skylineflyer:
I always thought lipos in a way had memories.

Nope................lipos do not have memories.
They do remember if they have been abused!
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Old Nov 12, 2013, 09:29 AM
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College Park, MD
Joined Sep 2002
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Quote:
Originally Posted by 4stripes View Post
They do remember if they have been abused!
Undeniable. They also remember just being used. Otherwise, they would last an infinite number of cycles.
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