I read somewhere (can't remember where) that lithium polymer batteries are best stored at 60% capacity. I have a set of four Flight Power EON X30 4350 mAh 3S lipo's that about three months ago I discharged about 1600 mAh each (40% +/-) for their winter storage. Yesterday I thought I would give those batteries a bit of an exercising just to make sure they are staying fresh. To my surprise, each battery took only about 160 mAh of charge to be fully charged. I was not aware that a lithium polymer battery would self refresh like that. Is this typical or am I doing something wrong? Any thoughts will be appreciated.

Jim Fruit

John:

I noticed the relationship of the charge/discharge numbers also. I am using the Triton 2 charger. It requires you to set the type of battery and its capacity, it then paces the charge or discharge rate. I just let it discharge until it indicated that it had used approximately 1600 mAh. This reads directly from the display. If I remember correctly it took approximately 45 minutes to do that, so I don't think I was making a ten times mistake.

I could more easily understand your point about charging by 1600 mAh in lieu of discharging by that amount. My charger not only indicates on the display, but it also turns on an internal fan during discharge so there is an audible difference. I think I am going to try it again. Thanks for your help.

Jim Fruit

Crist:

This is why I was not too excited about learning a new system (electrics). Now that I have switched, I will never go back. The problem is, I am always behind the curve and always learning.

Are you indicating that the Lipo should be stored at 3.8V? I thought that a single Lipo cell was rated at 3.7V max. (I will say that I have seen 12.4V on my fully charged 3S's). Curiouser and curiouser. I guess I never will completely understand this stuff. I am lucky that the batteries seem to be holding up.

Jim Fruit

Thanks Dean.

JHF

Hi Guys,
     I have been trying to keep my batteries at the correct voltage for storage.What is the correct temp a battery should be stored at?Will freezing hurt them?
                                                              Trax

When it come to storage capacity, I have measured every brand new battery before the first charge and regardless of who is making them they all come in at approximately 50% charge.  Now maybe they are all be made by the same company in China and are branded for whoever is selling them or maybe they know something.  Anyway I shoot for 50% when I am taking down a fully charged battery or I just store them where they end up after a flight.  Generally 22% to 30% depending on the plane.  I always store them in the fridge in a plastic bag.  I received have all kinds of recommendations from all kinds of experts and quite frankly I am not sure anybody knows the answer for what is best percentage of capacity and what temperature is best.  Maybe the engineers who design Li Poly batteries know and if there is one out there please speak up.
Andy

Jim
I am into electrics only as far as powering the electronics in my glow powered CL models. 
I bought an "iMax B6AC" charger  as it looked to be the best charger for the money for my needs which is NiMH and NiCad battery care.  I put the name in Quotes as it is not an iMax B6AC but a copy.  I have been suspicious of how it performs and I have performed a few tests.  By hooking accurate meters on while it is charging or discharging I have become suspect of any thing it says!
This charger is rated for 0.1 to 5.0 Amps charge current.  Here are the actual verses indicated charge currents I have measured:
Selected - Actual
0.1 A - .052 A
0.2 A - .156 A
0.3 A - .259 A
0.4 A - .362 A
0.5 A - .467 A
0.6 A - .570 A
0.7 A - .674 A
0.8 A - .778 A
0.9 A - .893 A
1.0 A - 1.00 A

I did not test it to higher currents as 0.9 A is the highest charge current recommended for the batteries I have.  I have only tested the discharge current at the 0.5 A and it measured 0.518 A.

I think this may explain some of your problem.

I am upset with the batteries I bought this winter.  NiMH Batteries rated at 1800 maH when charged at the recommended rate of 180 ma for 15 hours (2700 maH) will only provide slightly less than 500 maH power on discharge down to 1.0 V per cell.
Clancy