Reddit reviews UPG UB1280I Sealed Lead Acid Batteries
We found 3 Reddit comments about UPG UB1280I Sealed Lead Acid Batteries. Here are the top ones, ranked by their Reddit score.
Used In Ups Backup Systems, Spotlights, Flashlights, Exit Lighting & Other Equipment12V 8 AH .187 tab terminals, UB1280IThis item is not for sale in Catalina Islandub1280i
I'm pretty sure that UPS uses one of these batteries.
The amp you listed would work fine from a 12v battery. You then need some suitable speakers, bearing in mind you don't want anything to heavy or bulky. You'll also need to ensure that the output of your audio source (phone, MP3 player?) has sufficient output to drive that amp effectively. You've might also need to think about how you charge said battery. Sealed Lead Acid batteries are reasonably cheap and are available in more portable sizes than a full car battery.
If you want to go full DIY have a look at this Instructable
Physics doesn't care what you have on hand, 10W+ from USB just isn't going to happen.
These aren't too big and SLA is by far the cheapest route. It would run the Pi and screen for hours on a charge.
Run the Pi on something like this.
I'd wire it to a lighter plug and then have a socket connected to the battery, that way you could just unplug it and plug it into the car.