Wrong "time-to-empty" for multiple battery laptop

[Bastien Nocera]

On Fri, 2014-02-28 at 10:08 +0100, Joschi Brauchle wrote:
> Hello everyone,
> 
> I have the following problem with a Lenovo Thinkpad T440s laptop, but is 
> looks like a much more general problem that affects may users (will 
> provide bugzilla links later):
<snip>
> Thus, the "time-to-empty" flag is only available for BAT1 and clearly 
> only displays the time to empty FOR THAT PARTICULAR battery, but not 
> when using ALL batteries.

The front-ends are supposed to coalesce all the batteries together.

> As a result, the current "time-to-empty" is basically a useless 
> information for the user, as it ignores the second, fully charged and 
> available battery.

Again the front-ends are supposed to handle that.

> Imagine the case where BAT1 = 5% charged and discharging and BAT0 = 100% 
> fully-charged. Then upower will display something like ~5 minutes 
> remaining battery life (because it ignores BAT0), but in reality the 
> total lifetime of BAT0+BAT1 would be multiple hours.
> 
> Is this a known limitation?

Yes. Or you can use UPower 0.99.x which fixes that through the concept
of a "display battery", which will put together all the information from
all the batteries and not require every front-end to do that.

> I would like upower to provide an additional "overall-time-to-empty" 
> value using ALL batteries / energy sources installed.

That's already done, you're just using an old version of UPower :)

Cheers