FP charge rate

[Zilla]

I have a Flight Power 3S 25C 2500 and a 25C 2170. I am currently balance charging them at a rate of 2amps.
If I want to charge them a bit faster, what can i safely charge them at ?? My chager will charge up to 5 amps.

Thanks

Tim.

[Héli Suisse]

I would not recommend regular charging at a rate > 1C for this procedure will likely reduce life time of the battery. Lipos don't charge at Constant Current for the entire charge. And the Constant Voltage portion of the charge takes about the same amount of time no matter what C rate you charge at during the Constant Current portion. In other words you won't gain a lot of time in the charging process and the drawback of doing so will reduce the cycle life, so no real benefit!

[WillJames]

I agree 100%.

Good advice.:noteworthy

[MrMel]

I dont agree.

Going from 1C to 2C you benefit quite alot time, its above 2C thats almost no point.

Since FP and TP is the same chemistry (FP even better with matched cells) and Charlie over at TP did a 600 cycle test with 3C charging, the pack lost 13% capacity, I would say thats probably quite normal for a 600 cycles... meaning charging didnt do any damage or very very little.

I say that "it damages the pack if you charge over 1C is a myth", in the past, perhaps, now with 20/25/30C I dont believe it.

I have FP EVO20 6s packs that have charged at 1.5-2C almost every time and have above 280 cycles on them, its all about how you discharge them.

Balancing when charging is of course a requirement (and should be even at 1C...)

Also notice that newer 30C cells coming out from kokam and others has actually "standard charge rate = 2C" on them.

That said, since its always a risk since if something goes wrong, it goes wrong faster with faster charge, if you have the time, charge as slow as possible, if you are in the field or like me (two kids, never know when you can fly), charge under supervision at higher rates.

[Zilla]

Thanks for the replies. I think I will stick to 2.5amps.

[RobinJames]

It takes time for the ions to move around inside the cells and charge rates above 1C IMHO are not something I need to do. I may push it to 1.25C but for me, the benefits of approx 1C rates have paid off in longevity of packs.

Mel is a very experienced E-Heli flyer and I definitely respect what you are saying Mel, but for the people with little experience, staying at 1C is a good way to learn, then go to higher and less forgiving rates after they get experience. Higher rates make stuff happen faster and increase the attention to detail needed.

Get experience first then learn what works for you. Like Mel says, for him the shorter wait times and no perceptible decrease in pack longevity works for him. Sneak up on what Mel is doing when you are ready.


*** Edit - Crap, I posted this from my Wife (Robin)'s iMac. Sorry this is from WillJames

[Héli Suisse]

If you don't thrust the laws of Physics at least you should thrust our Administrator Finless

" This "usually" when the pack hits 80% charge is when chargers do this and chargring from that 80% to 100% takes the SAME AMOUNT OF TIME regardless of C charge rate! Oh and that last 20% takes about HALF of the total charge time!
"
from http://www.helifreak.com/showthread.php?t=45504&page=10