Portable power supply (for laptop or others)

[Evander]

I'm gonna be spending most of my days writing a book, and I'd like to start doing it outside. My laptop battery is good for maybe 3 hours using a word processor, it's an old laptop and HP stopped selling batteries for it and 3rd party batteries have not worked well so I can't buy another (have had problems with charging, I was able to find a company that replaces your old battery cells but leaves the charging circuitry so that's why my official battery still works so well).

So I was thinking of getting some sort of portable power supply but have no experience with these things so I thought I'd get some input from others as to what to get. Looking to spend under $75, and get around another 3 hours of use

 

[Jiggz]

If you have access to a car battery you can use an inverter. a 350W inverter can easily power up a laptop. A car battery can one from your car or from a jump start power pack . It'll cost you more than $75.00 though.