LiIon batteries are fairly new and much like NiMH they were supposed to have no memory (compared to NiCd). That being said that the fancier the battery chemistry the more finicky they get. NiMH in particular is very very sensitive to being trickle charged (it quickly destroys their capacity) and I expect that LiIon is much worse.

I've been dealing with short lived (2 to 3 year) UPS batteries (lead acid) and my only guess is that the UPS's must be overcharging the batteries all of the time because I've worked for big-time UPS companies where a single 2V cell is the size of a small filing cabinet and lasts > 20 years (also lead acid).

Note that nobody selling home energy systems (solar or wind) uses anything but lead-acid batteries! The benefits of LiIon and NiMH is size and weight.

That's why I argue that hybrids should be built with a 5hp IC engine (or whatever is needed at 65 mph) so that the IC engine is optimized for efficiency and minimum emisisons and pretty well run like a "fuelathon" car - you know the ones where they get > 1,000 mpg. Then the electric engine pretty well provides all acceleration and the battery pack cost/size/capacity is minimized.

Any car that has > 50 hp output is not fuel efficient.

The book The end of oil : on the edge of a perilous new world / Paul Roberts explains it best - the past 15 years has been a move towards more powerful cars that get the same or worse milage than previous generations. Before then we built more fuel efficient cars without performance/power taking a back seat.

What we need to do is start building 30 to 50 hp electric cars with a 5hp IC engine to power a small battery pack. Yes we'll have 15 sec 0->60 times but
who gives a damm - at least it'll get better milage (and have lower emissions) than a 1990 vintage Chevy Sprint. Currently we don't have any 4 seaters in production that'll touch my '91 Sprint for milage or emissions. It's disgusting.