One cell is at 4.14, and the other 4.12. Is that too high for a 5200 40C 2 cell 7.4 LiPo?

In my experience lipos usually get puffy for 2 reasons:

1. you leave them sit with a full charge, they should have 60% when they are at home sitting

2. they get hot hot while fully charged. While at the track try to keep them in the shade


your voltage is fine if you are about to run

How long does it take for them to get puffy when sitting with a full charge?

When I first got LiPos, that's what I would do. I knew that you should never overcharge them, or let them fall below .6 volts. But no one ever told me that they sould never be left sitting fully charged. Now I'm paying for it. I have been charging them 50-70%, when not in use. but It's a bit too late of a few of them.

My question is how long is too long to have them sitting at full charge. A day? A week?

My guess... In a week or two. I race 3 to 4 times a month, and have left them at full charge for 5 to 7 days at a time.

more than a day or two
I would not push it at all, try to charge as close to use as possible

Too high for what? The replies that followed your question are all over the place.

i've been into a situation where my lipo goes S1: 4.20 S2: 4.17. thats what good charger are for rite? i only have lipo with hard case, so i donno if its puffy. i fully charge my battery, leave it 2 months.. nothing happen.. i still have my runtime. oh btw its 2 years old trakpower 4900 25c

Mate, I'm like you, I have two, 2 year old Trakpower batts that I never balance, leave them fully charged and race and abuse them, yet they keep going.

i've seen lipos last few days before it deteriorate in capacity, burning like fire crackers and so on. dont want to mention any brands here but some good bang for the bucks lipos do last. but mostly we get what we pay for.

I only used ThunderPower, and SMC LiPos. And I have to use hard-case LiPos, if I want to race at ROAR events. Lately, I've been running them down, and then charging them to 60-80% when not in use. Not sure If that's how it's done, but that's what I've been doing.
It was in the past, that I would charge them at full rate, and let them sit like that for a week, or so. And I think that's what's happening, now. It least that's what I believe it is. I have never overcharged them, and I always keep them balanced with in .02 volts of each cell.

Another thing thats supposed to not be good for lipos is running them all the way to the lvc in your rc. Supposed to not withdraw mor ethan 80% of teh lipos capacity.

How puffy are yours? If they have just a little, there has been some internal changes/damage, but nothing terminal. If puffing is real pronounced, I'd be getting concerned about continuing to use them.

I've never ran my LiPos down that much. I'll run a 5000 LiPo one to two races, before charging them again. But mostly, they get charged right after a race.

As far as puffyness goes... I couldn't tell you. The case on my TP Lipo came loose, but I managed to pop it back in, and re-tape it. That's what got me worried in the first place. And noticed a slight bump in my SMC. I wouldn't have notice it if the seam on one side was slightly extended.

I leave mine full for a week sometimes and they are all fine after almost 2 years, a month might not be such a good idea...

2 days? 2 months may be bad, not 2 days...come on think about it.