Question about cell balancing.

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DemonRC1

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How often to you guys balance your lipo cells? I don't wanna be anal about it and don't want to neglect them either so I figured I'd ask.
 
I am uneducated on this also. I thought they balanced when ever they charged. Balance charger? What else do you do to them to balance?
 
I see alot of 1/8 scale guys charging at the races without the balance port and they say them balanced them all out the previous night. I always figured it was a "conditioning" thing that you do to a pack here and there kinda like cycling on NIMH packs. Then, somebody threw me off and told me that you should plug in the balancer and set the chanrger on a balance charge and set the amps to whatever you normally charge at everytime. That threw me for a loop. I was told to balance charge every few runs on the batteries at like 1 amp.
 
I balance charge everytime. My charger can balance charge at 5amps which is the same amp rate as the fast charge....go figure lol
 
I guess I need to pick up a $20 LCD cell monitor tommorrow an find out myself how well these Sky Lipos hold their mojo. If I can get away with a handful of cycles before balancing, that would be good.

I talked to a heli buddy of mine that is really die hard about checking each pack on a cell monitor before and after each charge. He told me he's just being anal and he could go a half dozen cycles before the voltage was off enough to justify a balance. That is as long as he doesn't totally discharge them each time. I guess that's why I see that most 1/8 electric guys aren't balancing at the track.
 
So I have 2cell lipo 5000 7.4 does that mean I can charge it up to 5 amps? I been charging at 2 to 2.5 afraid I'm to high on the rate, so I can set this higher? I balance every time I charge. You hear about 1c and 2c whats that mean?
 
teedog12 said:
So I have 2cell lipo 5000 7.4 does that mean I can charge it up to 5 amps? I been charging at 2 to 2.5 afraid I'm to high on the rate, so I can set this higher? I balance every time I charge. You hear about 1c and 2c whats that mean?
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1c charge is charging at the same amps as the pack's capacity. So if you got a 5000mah pack you can charge at 5 amps safely. I'm sure there's a better definition somewhere that sounds better but that's basically how it works. 2c charge is charging at 2x the capacity of the pack. So on a 5000mah pack you charge at 10 amps.

The C rating also applies to discharge. A 40C rated pack can discharge at 40x the pack's capacity. So 40 x 5000 = 200,000mah / 1000 = 200 amps. That basically telling you the pack can discharge at 200 amps safely.

Oh, I kinda polled 20 or so guys at a local track about how often they balance their cells. It's was pretty much a 50/50 split. 50 being that they do it everytime and the other 50 do it every few cycles to never. I think 3 or 4 guys told me they don't even do it. I wasn't surprised by that considereing they were running Traxxas Slashes, a Stampede, and a beat to hell Ofna buggy conversion. The 10 or so guys running high end stuff like Losi's and Xray were balancing at least every 2 cycles.
 
From my experiences with 1/8 electric back when a good C Rating was 20C and the Mamba Max 1/10 ESC modified was a good unit for the money, you will want to balance your packs when you charge them.

These larger vehicles put more strain on the batteries from what I have seen in 1/8 that unless you have a top dollar pack that gets regular use will have slight variances in the balance between cells. Not much, but over time that can make a difference. Since most chargers now will balance charge your lipos for you, just go ahead and do it.

Also, you will want your dual pack setups to be within balance of each other and similar usage on the packs as well. If you can dedicate a set of batteries for that particular vehicle that uses a dual setup, thats the best thing.

I currently have been using the Hyperion 600 series dual charger for awhile now. Other than no discharge feature i can do two 4S battery packs Easily and balance charge them together as if they were 1 larger pack.

As a side note, you also want to pay attention to the wattage that the charger you are going to use puts out. Seen a few newer multichargers than can only do like 50W per channel, no good for 3S - 4S usage for any reasonable amount of charge time.

Lastly, run a reasonable cutoff voltage. I use 3.2V per cell. Going lower can cause all kinds of funky voltage discrepencies between cells which if you plan to not balance charge all the time is bad.
 
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