27ah and 150 watts?

Posted on 2017-03-23 05:48:00 in Engineering by ROCK

I read that the average 15" laptop puts out 150w or less, which I am not certain on since most of this is said 5 - 9 years ago. 

but I am looking to buy a portable battery that states only "27ah". 

I think I need the "voltage" as well? but the battery says nothing about this. 

I am new to these things and am wondering .... 
I need a portable battery that I can plug in and charge and when it is full, take it with me and use it with my laptop. 
If my laptop puts out 150w and I need the battery to last for 12 hours nonstop, what specs should I be looking into?

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