I don't think so; my N800 still has its original battery from early 2007, hasn't been turned off at all in all that time and it still holds about the same charge as it did when new.

LiIon and LiPol batteries should last at least 3 years or 300 full charges (partial recharges count as partial), which ever comes first; newer (and better) ones now go for 5 and 500 resp.

You cannot simply measure battery life in cycles, partiial or full - its only an estimate. There are several other factors that affect the lifespan of a battery.

The forumula for lithium-ion composition is almost always changing between manufacturing batches. One batch will last years while another will last months.

Temperature - Constant temperature variation shortens battery life. High temperatures shorten battery life. Extremely low temperatures shorten battery life.

Current draw - Greater current draw generally shorten lifespan.

Charge style - Float charges are harmful to lithium batteries, maintaining a >95% charge for a long time shortens lifespan, maintaining a <40% charge shortens lifespan. So leaving a tablet plugged in when not using it will shorten the lifespan.

Build - series cell batteries do not charge equally (doesnt apply for our tablets)

when i leave it plugged in it is never turned off.

Float charges are of a high voltage than the liion battery runs at. leaving it plugged in 100% of the time is not good whether its running or not.