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-   -   LiFe Batteries (https://www.rcuniverse.com/forum/questions-answers-154/10636620-life-batteries.html)

jetmech05 07-24-2011 12:29 PM

LiFe Batteries
 
I have been running Li Ion batteries with regulators in a couple of ships...I re charge when voltage fell below 7V with a 1 amp load.
Picked up a couple of Life batteries A123's right off the charger they fall below 7V with a 1 amp load.... what is the best voltage to re-charge at?
Thanx in advance

scale only 4 me 07-24-2011 12:49 PM

RE: LiFe Batteries
 
A123s are a different animal completely, don't go by the voltage alone, the nominal Voltage is 6.6 or 3.3 per cell. and they will hold at 6.7-6.8 for the whole charge, then fall off fast.

What you need to do with them is charge, fly a complete flight or 2, and then recharge, then calculate how many Milliamps you had to put back into the pack for X amount of flight time,, then you can figure your flight time per charge cycle.

Good luck,, I love mine

TimBle 07-24-2011 10:45 PM

RE: LiFe Batteries
 
For LiFe battery packs with a nominal of 6.6V recharge at 6.5V.

For Life battery packs with a nominal of 6.4V, recharge at 6.4V.

Below these voltages you are running a huge risk as you are approaching the "cliff" (they drop off super fast.)

I am not a fan of the fly, recharge and fly methos as you may not be pulling the same amperage on every flight. Depends on manoevres, airspeed, air density. E.g I tried the fly and charge over several flights. I found that on my pattern plane flying the same schedule over a 6min flight I was using from 80m.A to 130m.A.
Sure it provideds you with a good idea of how many flights to expect before recharging but the commercially available battery checkers for Life and LiPo are accurate enough to provide the same information with a larger safety margin.
And Safety is the main reason why we check, right?

scale only 4 me 07-25-2011 03:41 AM

RE: LiFe Batteries
 
Timble,
I agree it's not a perfect system, but it gives you a good idea how much flight time a charge will give you.

Last week a buddy was showing me his FMA Cellpro 4s charger, it calculates and shows you the pack capacity % before the charge cycle begins,, can be used as a battery checker and a charger,, for $55-$60 I may pick one up.

p.s.
I wouldn't fly any type pack when the shown voltage is under the nominal rated voltage,,, IMO that's just crazy

jester_s1 07-25-2011 05:45 AM

RE: LiFe Batteries
 
No need to buy a charger just for this unless you just need another charger. I use them and just erred on the side of recharging too soon for about 2 dozen flights until I had a good average figure for battery usage. Now I recharge at roughly the halfway point and have zero problems.


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