Electrical (?) problem on a Dell Latitude 5420

[etienoo]

Hi,

I have a very annoying problem on my laptop Dell Latitude 5420.
It works perfectly fine when the battery is 100% charged (and plugged) or when it is unplugged (thus the battery is discharging).
However, when in charge (and lower than about 90%), the computer almost cannot be used: the mouse moves incredibly slow (similarly for the touchpad). Furthermore, it seems that the hard drive responds very slow: saving a tiny text document (which would usually take a few milliseconds) takes 10-20 seconds.

When I'm at work, the computer is always plugged, and this is not a problem; however, after I use the computer in a train or a plane (hence without power supply), I have to wait one hour before it becomes fully charged to use it − and this is really annoying.

I installed two systems one after the other
1) Ubuntu 11.10 64 bits
2) XUbuntu 12.04 32 bits

The problem was the same in both cases, from the first installation.

I wonder whether it comes from some incompatibility coming from Ubuntu (although this model has been certified for Ubuntu), or from a hardware problem in the computer.

Thanks for any hints

[SlugSlug]

I'd have a poke round in the BIOS

[etienoo]

What could be the problem?
I mean, what could I investigate in the BIOS?

Thanks!

[SlugSlug]

look into power management see what options are there, maybe disable it ?

[etienoo]

I looked into the BIOS, where there is little option (not even the possibility to disable anything).

However, this BIOS is a modern system where one needs a mouse and, strange enough, the mouse works perfectly well, even if the computer is charging. But booting XUbuntu right after will create the problem with the mouse in XUbuntu.
So this problem might (partially) come from the OS.

Did anyone experience a similar problem?

[andriansah]

Could it be it's battery life problem?
http://ubuntuforums.org/showthread.p...highlight=5420

[etienoo]

I don't think so, because it does so since the first boot of the computer (which was new when I got it), and it doesn't work until the battery is charged 90%.

However, when unplugged, the computer lasts for at least 3 hours (until the battery is almost 0%).

[typhoon_tip]

Can you write here how many watts does your power supply unit have ? It is written on a label in the back of it.

[etienoo]

No, I can't find it.

I read the following:

Input :100-240V ~ 1.5 A 50-60 Hz
Output: 19.5V ~ 4.62A

But no watts…

[typhoon_tip]

Well enough, just multiply Volts * Amperes, = 90W. It should be enough to recharge your battery while using the laptop at the same time ! Some laptop have this protection, they are not recharging if they detect the power is not enough to recharge and use at the same time, or they scale down the power of the system. In your case, seems a bit on the extreme of the latter.

The 90% "threshold" is because when the battery is below 90% it usually get pumped much current in than otherwise.

Also, can you write down your battery specs ? If you go to the battery menu, click "Battery" then "Laptop battery", tab details will show you the capacity. Post that content as well !