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# [OT] EE101 (was Re: power management problems)

```* Florian Reitmeir <florian@reitmeir.org> [070913 09:22]:
> On Thu, 13 Sep 2007, Marvin Renich wrote:
>
> > * Florian Reitmeir <florian@reitmeir.org> [070913 08:45]:
> > >
> > > design capacity:         4800 mAh
> > >
> > > this can't be right, it should be something between 10000mAh and 100000mAh
> > >
> > > --
> > > Florian Reitmeir
> > >
> >
> > No, this is correct for the 53Wh Dell battery.  Mine even has 4800mAh
> > printed on the battery.  The Dell 80Wh battery appears to have a design
> > capacity of 7200mAh, though this is not printed on the battery as it is
> > on my 53Wh battery.
>
> 1W = 1000mW
>
> so 4800mAh = 4.8Wh instead of 48Wh
>
> My AA batteries for my mouse have 3600mAh each.. so with 2 of them, i have
> 7200mAh...
>
> --
> Florian Reitmeir
>

1W = 1VA

My battery has a rating of 11.1V, so 4800mAh * 11.1V = 53000mWh = 53Wh.
(If it looks like I've rounded, I have; 4800mAh only has 2 significant
digits, so the answer can't be more precise.)

You are confusing power and energy.  Power is the rate of consumption
(or production) of energy per unit time.

Your AA batteries (if they are rechargeable) are 1.2V, so they hold a
total of 1.2V * 3600mAh = 4.3Wh of energy.  Compare this with the 53Wh
of my laptop battery.  If your batteries are standard alkaline,
substitute 1.5V and you get 5.4Wh.

It is perfectly reasonable for a AA battery to have a power rating on
the same order as a laptop's Li-ion battery; it just doesn't have near
the same amount of energy.

...Marvin

```

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