LiPo Longevity

[MikeA]

Evening all. A comment from the mighty Wookie had me wondering - just how long in terms of years should LiPo batteries remain safe to use?

I have two RX LiPos in my Ventus and they have been sitting with about 80% in them (I checked) for over a year. The batteries themselves are about 5 years old and have had pretty low use plus I don't tend to top them up before flying as I'm led to believe that doing this is not a good idea. I wait until about 25% and then charge them. So is there anyone out there with any views on this? Do old LiPos show their age or are they still good to go?

Cheers, Mike.

[GordonT]

I consider any Lipo that's over two years old to be on borrowed time. That being said, if not being unduly stressed and lightly loaded, the better ones can last much longer. I'm able to check the internal resistance of the cells, which increases with age - if it gets too high, I know not to expect too much of a battery. Also, if a battery is puffed up, it's best disposed of. As for storage - cells at around 3.8 Volts and in a cool place. I use a convenient beer fridge for storing all my batteries - it has other uses, too.

[Mick Forey]

From my experience there is too much variability in LiPos to provide a good answer. I have some LiPos that are 6 years old, have been used well within their capability and are still good for light duty. Others deteriorate fast after 15 cycles. Price is also not a good guide to LiPo longevity as I have had plenty examples to show that there is no correlation. Regular checking, balancing and charging at 1C max seems to produce good results. I keep my regularly used batteries at full charge ready to use but store them at 3.8v/cell if they will not be used for a few months.

I have been an electric only modeller, of most persuasions, for 7 years.

Mick