rscamp
Veteran
Location: Ontario, Canada
| Robert.
If two LiPo battery packs are balanced to start with and they are of the same age, type and size, connecting them in parallel will help keep them balanced. However...
You won't see outright failures due to sub-optimal storage that early (within a year). On average, all you will see are slightly greater than necessary reductions in capacity.
Check the technical literature. Storage at 100% SOC is not recommended. This reduces cycle life. Manufacturers of battery maintenance ICs for portable electronics know this and design their components accordingly. This is why the batteries in your notebook computer slowly drop from 100% SOC after they are charged. The charging circuit DOES NOT try to keep it at 100% all the time even if it is plugged in. On a related note, the increased temperature inside your notebook is a major reason why the lithium chemistry batteries generally don't last very long. Granted, for our hobby use which is quite severe, storing at 100% is not a serious problem, but it does reduce capacity more quickly.
Another disadvantage of storing at 100% SOC is it will increase the speed at which individual cells within the pack become unbalanced.
LiPos deteriorate significantly with age even if unused. Storage at cooler emperatures prolongs life. The absolute best thing you can do to store LiPos for an extended period is to put them in a state of charge (SOC) of about 40% and keep them very cool, say near 0 deg. C. This will greatly increase the time it takes for them to get to the point that they can only deliver 80% or their original capacity, which is generally considered their useful life.
Rob |
