What are the proper methods in charging/storing an e-flite 150mAh lipo battery for a MCX2 helicopter?

Recently, I found out (the hard way) that 2 out of 3 of these batteries I have had for 6 months (with no issue) are no longer usable (will not hold a charge).

Not sure what I did wrong - overcharged them, charged them before they were fully drained, stored them in too cold of temperature?

I am using the stock charger that comes with these batteries (so I know I am using the correct charger) - and after they are charged the charger still blinks (trickles) as if they are charged and then supposedly shuts off charging (so overcharging should not be the issue - am I right?). I may have charged them again before they fully drained (but never knew this was a problem - is it?). Also, the only other thing I can think of is that I have had them in the helicopter box in my trunk for awhile in cold weather (could that be it?). Finally, these batteries were fully charged/not drained and stored for several months (is that okay?) Any others with these batteries issues? Are they supposed to last many years? Thoughts?

Thanks to all in advance for any insight with this...

One thing I do know about LI-PO batteries is they cannot be fully discharged.
As soon as you notice any power loss shut down the heli, let the battery cool down.
After they cool down you can recharge them.

yes, cold will affect them! i recently have experienced the same problem where all three of my 150mAh single cells are no longer useable!

with the single cells, unless you have a super-duper charger, you will find it quite difficult to drop them to the correct storage charge (in 2+ cells they should be stored with about 50-60% capacity if going to be left for any length of time!) but Nick is very correct in saying that you should not drain LiPo's completely! the other way of keeping them in tip top condition is to charge them each and every time they're used, even if it's just to check correct control movements, any time you take some of the charge out, put it back in!!

have fun with the mCX2 and it's brother, the mSR is even more fun!!!!!

Matty )<+}}}}}}}]@>

Okay - now I am at my wit's end!

Firstly, thanks to ALL for posting these replies - and to Horizon Hobby for replacing my copter - even though it appears it was unnecessary now.

Latest news - I now have a brand new MCX2 and it works perfectly when using the 120 mAh li-po battery that comes with it. HOWEVER, when using a brand new (tried 3 now) 150 mAh li-po batteries, it will not fly forward or reverse (all other controls work - hover, left and right, sideways, up and down, etc.). What the heck?! How is this possible - am I losing my mind?! I KNOW these copters work with these larger capacity batteries - my old one did extremely well before those batteries went dead. I am ready to pull my hair out and drop kick this hobby to the trash for good. Please - any insight here?

Thanks again for y'all's patience - I wish I was not losing mine...