# Thinkpad Laptop with two batteries - Discharge order?

## Negated Void

Hello,

I've got a Thinkpad W520 and it has an add-on "slice" battery (optional, second battery). However, when i'm running with both the batteries, it discharges the main one first. It should discharge the secondary "slice" battery first. When the main battery dies, the laptop powers off.

Is there a way to get this working correct? o.O

Thanks!

--Murph

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## dmpogo

 *Negated Void wrote:*   

> Hello,
> 
> I've got a Thinkpad W520 and it has an add-on "slice" battery (optional, second battery). However, when i'm running with both the batteries, it discharges the main one first. It should discharge the secondary "slice" battery first. When the main battery dies, the laptop powers off.
> 
> Is there a way to get this working correct? o.O
> ...

 

How do you know that the second battery is working at all,  if laptop powers off after main discharges ?

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## Negated Void

Well, the battery widget in KDE shows two batteries, and I watched it charge.

I don't know that it's discharging at all, in fact I suspect it's not.

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## dmpogo

 *Negated Void wrote:*   

> Well, the battery widget in KDE shows two batteries, and I watched it charge.
> 
> I don't know that it's discharging at all, in fact I suspect it's not.

 

you can look at detailed information in 

/sys/class/power_supply/BAT0  and BAT1

to see what they are doing at any given moment

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## Negated Void

It seems that I need to install tp_smapi so i can issue a 'force discharge' on the correct battery.

Sadly, it doesn't support the new W520 yet  :Smile: 

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## chiefbag

Forget the fancy stuff, get a multimeter and a piece of wire and a small bulb.

You will soon find out the actual state of the battery then.

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