The manual should tell you what it can take and for how long. Just don't listen the sales people, they claim to use it for boosting battery dead cars during winter.
p.s. your cd-rom, cdr-rw, dvd, floppy only use juice when running so don't count them in.
<font color=red>Handsome A7V133 looking for long term relationship with a XP CPU. Prefer non smoker.</font color=red>