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Laptop battery running time

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Laptop battery running time

Postby Amnesiac5 » Thu Jul 20, 2006 1:52 pm

"Important" question
I'm considering buying a replacement battery for my laptop (Fujitsu-Siemens Amilo L7300). I've seen compatible batteries rated at 3800mAh, 4800mAh, etc. What effect (if any) does this have on the battery running time?

Recently, I bought my son's laptop to use on the commute to my new job. I have between 1 and 1.5 hours (each way) when I can use it. The longest the battery has lasted is about an hour. This means I have to charge it when I get to work and again in the evening when I get home... all a bit of a drag and means I can't reliably use it on lengthy journeys. It also means I have to keep an eye on the battery pretty constantly after the first half hour, and can't trust it enough to put into standby mode.

The data sheet indicates that there are two battery options

Li-Ion battery cells, 8 cells, 14.8V/2150mAH
    approximately 2:30hrs battery runtime
Li-Ion battery cells, 4 Cells, 14.8V/2200mAH
    approximately 1:10hrs battery runtime
That the lower mAh gives a longer run seems counter-intuitive, or is that because of the number of cells?

The laptop battery is rated 2200mAH so seems to be lasting as expected.

I use the laptop for programming so there's a lot of disk thrashing during compiles, is there any way around this? I tried compiling to a 2GB USB pen drive but it was unacceptably slow.

Could I reasonably expect to get more running time out of a 4800mAH (say 3 hours) given my usage pattern? Or would it actually have a shorter running time?

I'm still getting used to computing on the move, but all-in-all this isn't a bad machine (a bit big when the train's full), unfortunately if I can't improve the runtime I'm going to have to buy a replacement.
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Re: Laptop battery running time

Postby aspettl » Thu Jul 20, 2006 8:17 pm

Amnesiac5 wrote:Li-Ion battery cells, 8 cells, 14.8V/2150mAH

Here is the mistake: A battery with 8 cells has appr. 4400 mAh.

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Postby Amnesiac5 » Thu Jul 20, 2006 10:30 pm

Aaaaahhhhh... that would explain the discrepancy in runtime. Thanks. :)
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