Charging Rate
 

Hi peeps,

Probably a really basic question ... but just want to get this correct ;

Up until now I've only had 3S 11.1v packs and only ever charged at 2.2 (which I believe equates to 1C). Correct ?

I have an Overlander 14.8V 4S 3350 Lipo pack, it states on the back that the recommended charging rate should not exceed 2C.

Based upon that info, am i correct in thing the correct charge rater for this should 33500x2 ? ie 6.7A on a balanced charger

Is there any advantage of charging at a low rate of 1C ( ie 3.35 A ) ?

Thanks in advance ...

Your calculation is correct, 6.7 amps would be the maximum charge rate for a 3350mAh LiPo with 2c charge rate. Charging at a lower rate may be slightly easier on the battery but these days 2c isnt a high charge rate, I'd have no hesitation in charging at 6.7A.

Many thanks.

Here you go, hope it helps.

http://www.wattflyer.com/forums/showthread.php?t=65869

Regardless of the label statement - I'm a skeptic and always view manufacturers claims for extra with caution. 2C is not a fantastic rate and should be OK.

But I believe that care for a battery is in its charging .... if not pushed too hard - life is prolonged, greater capacity is got back into the pack ... overall for a little bit longer cvharge time - the benefit is worth it.

On Lipo's - unless really need to - I never go over 1C rate ... that is if it's a 2200mAh pack - I charge at 2.2A..... a 3350 ( Ithink you added a zero !!) at 3.35A but as said 2C is not so hard nowadays ... so 6.7A ... but me ? No - I'd stick with the 3.35A for general charging and expect to see long life from my pack.

Nigel

Guess that's why I'm an A123 battery fan. These cells are about 35% more weight, about 35% more volume, and are 2.8 Volts at 35 Amps. But they do not have any fire issues, puffing issues, and can be charged at any rate your charger will put out. My packs are actually built into the model and are never taken out.

I've been charging my over 100 A123 cells at about 4C now for years, and all is well.

What is a problem though is recharging battery packs for giant scale models. I'm charging a 12S2P A123 pack as a 6S4P pack with a Cellpro Powerlab 8 charger that is charging at 30 Amps. This is pulling 55 Amps out of the 12 VDC supply. IMHO, no across the counter deep cycle battery can handle that for more than a few dozen charge cycles.

FWIW I always charge my Gens Ace Lipos at between 3 and 5c (limited by the 30A my charger can push into them) and after over a season of hard use they are still performing well.

Life is too short for 1c charging IMHO.

Thanks all, the policy I have adopted is

1C on packs that don't state the charge rate (some cheap Hi-Energy 3S 2200)
2C on packs that state a 2C charge rate
2C for some of my packs claim 5C in emergency by recommend 2C

That's all folks !

Ditto, and I'm convinced it has made a significant difference in the battery life. I'm not one those people who flies numerous times with the same battery at the field, so I'm never in a rush to charge over 1C, and generally charge at less than that.

I hear ya! From what I've heard from quite a few guys who've been doing it for years, charging at higher than 1C it doesn't shorten the life of the pack. Personally I've never charged at more than maybe 1.5C but that's only because I was using an antiquated AF109 charger with Blinky balancers. Now that I have a PL6, an iCharger 106B+ and a 25V/57A server supply I'll be charging at higher currents. That being said I still probably won't be charging my 6S 5000mAH packs at more than 2C because I'll be parallel charging as well.



Mike

Which is why I just made the decision to buy a generator. I had been using a deep cycle battery and when charging 3S packs of 2200mAH or less with a charge or 2 of my 6S 4000mAH it works OK. But now that I'm getting into bigger packs they just won't cut it. Even running several in parallel is pushing it and then you have the weight of all those batteries.



Mike

Let us know which generator you've picked up, and how it works out. As for SE Wisconsin, they are forecasting ANOTHER round of snow today! :censor:

It's a Champion 2000W Inverter Generator. Picked it up a one of the local Farm & Fleet stores. They have them on sale through March for $469, $100 off regular price. i haven't used it really yet but i have started it and run a few tests, looks promising. Very quiet in Eco mode and not too bad revved up. If you check out "Generator Question" in that "other group" in the Batteries and Chargers section you'll find it.

Yes, it has been a big snow year here in WI. I'm in the Falls and it's snowing right now. Not nearly as bad as Chicago or especially Minneapolis area but still sick of it!

Sorry to drift off.



Mike

Thanks for the info, be sure to post how it works when that :censor: snow melts. (We just got another 7 inches of the stuff in my driveway today)

Will do.

We didn't get much snow up here, maybe an inch.

Its not snowing in Texas. The wind is horrofiying 15 to gust to 40. Edward2

I guess it doesn't matter where you live, you'll get some form of weather that'll mess with your flying. It hasn't snowed hardly at all here lately but it's been raining so much that we've got flooding all over. The flying field where I live now is a mess. I moved down here near Milwaukee a few years ago but I still get the email updates from my old club up in central Wisconsin and they're having the same problem there too. They've had to postpone their field setup two weeks in a row because of the wet conditions.


Mike

Yeah
Another RC club in the Milwaukee area gets flooded out whenever we get heavy rains. Right now, the word is, that RC field and parking lot is under a foot of water.

Our RC field is also in a flood plain, but in the past 20 years, it's never been close to being flooded out.

As for charging LiPo batteries, most of my RC club members are not charging them at over a 1C value. I'm charging one of my A123 packs at about a 5C value. The 12S2P pack is being charged as a 6S4P pack at 30 Amps. That's about 3.5 C, a value limited by the output power rating of my 6.5 Hp Harbor Freight Engine, 80 Amp alternator setup for field DC power.