question about external laptop batteries

Hi,

I need to know if it's possible (and safe) to power a laptop from an external battery while at the same time charging the external battery?

Meaning I have an external battery, I plug that into mains, and then I plug the battery to my laptop at the same time.
Does it make any difference whether or not the laptops original battery is in place?

Also, does the voltage that comes out of these external lithium batteries usually fluctuate? Or is the 12v actually 12v?

 

it depends on the voltage required and if the product has quality.
about leaving the original battery, you can leave it in place. but I don't see much point in it, since you will be using external power. it will only detriorate the charging cycles.

 

How did you plan on doing that? I have never heard of such a thing.

 

Depending what circuitry is between the external battery and the mains, I would think you could probably overload the charging circuit as it will effectively be providing the power for the notebook and the power to charge the battery. If it is not made to do this - you have a very dangerous or at least an expensive (when it goes up in smoke and nothing works anymore) situation in hand.

Confirm that the charger/charging circuit has the capability to provide the wattage the computer needs, while also providing the wattage the battery needs to charge too. The total needs of both these loads presented to the charger should be below 80% of its rated output capabilities if you want this to be an ongoing and/or consistent usage scenario.

Good luck.

 

Thanks!

My laptop battery is completely dead, and my plan was to use one of these external batteries to power the laptop. The seller responded to my email saying that if wattage the computer needs is below 75w, then this battery should be ok to power the computer and charge itself. Specs for the battery say the output is 74Wh at max.
The original adapter of my laptop gives 65w, so looks like it should be safe. Anyways, I'm not gonna leave it unattended..

@Padme: I simply take the original battery out..

 

sampsa,

just need to point out that the capacity (the '74Wh') of your original battery should have no bearing on this issue (using and charging the external battery at the same time).

What makes me slightly less uneasy is the fact that your adaptor is rated at 65W... if the seller states his is safe for up to 75W, then you should be good: assuming that the external battery is using (relatively) the same amount of power (in Watts) as your original battery to charge itself and has some power left over to power the notebooks components too.

I would definitely recommend to not have the old 'dead' battery in the notebook - it will add an unnecessary strain to the new power adaptor and might even make it peak at over the 75W the seller stated it can handle.

Hope you found this useful.