That's been my experience across manufacturers. On Lithium POLYMER at least.
The gereat danger is over discharging,
and they do this all by themselves, albeit slower than Nicad or NiMh.
The danger of storing a charged pack is accidental shorting, explosion and fire. Ypui need to be aware and take precautions as to where and how they are stored. Cool temperures lesseen self discharge, insulation lessens shorting, and storing in a fireproof safe is no bad thing.
All you can do is simply keep charging it and hope. If the over discharge protection wasn't up to it the battery is shagged.
Lots of e-flyers have found this on Nimh and Li-Ion. Over discharge them (too far or too fast) and capacity is permananetly lost, also the cells may go out of balance, resulting in some cells getting overcharged, which is frankly dangerous with LIPO.
Best thing is to somehow access individual cells, and recharge each one and work out if they have correct capacity. OTOH the time and equipment probably costs more than a new pack.
"Charge fully before storage. Store disconnected from load. Li-poly will store for at least one year and still retain at least 50% charge. Store at normal room temperature." Bill(oc)
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