laptop life & battery capacity
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From: Bill Todd on 13 Apr 2008 06:20 Jonathan Thornburg [remove -animal to reply] wrote: > Morten Reistad wrote: > | There is nothing barring us from making a laptop you can work on for > | a day or so with normal battery cappactities. 6Ah @ 14V is about the > | limit, or 84Wh. That means we would need to limit power for the system > | to an average of 8W. > > Bill Todd <billtodd(a)metrocast.net> wrote: >> I have no idea whether that's feasible or not, but what *does* seem >> clear is that it's not at all 'normal': a quick review of the current >> under-$1200 Thinkpads at the Lenovo site indicates that their standard >> (6-cell, hence presumably nominally 11.1v.) batteries are rated 2.4 Ah, >> or less than 27 Wh. Even if their optional 9-cell units actually >> increase that by 50%, that's still less than half the number that you >> quote above (and not the standard - 'normal' - part in any case). > > Thinkpad batteries come in multiple sizes; the ones I've met are 4.4, > 6.6, and 7.2 amp-hours at 10.8 volts (= 47.5, 71.3, and 77.8 Watt-hours). The fact that my old (570E) Thinkpad battery was only 2.6 Ah was the reason I went to Lenovo's site to check what current battery capacities were. The only ones for which Ah ratings were listed (for the sub-$1200 laptops that I skimmed) were the standard 6-cell, 2.4 Ah units. They did mention optional 9-cell units which I'm sure were more robust, and I certainly don't doubt your own experience - but Morton used the phrase 'normal battery capacities' and I took that to mean what one normally gets (unless one specifies something else). .... > There's presumably some room to increase battery capacity within a > "tolerable" overall laptop-weight budget. Perhaps - but that, too, would not be a 'normal' battery (at least by today's standards). - bill |