Pwlyt

RichBinAZ

Sounds like a short somewhere, although it should have popped a fuse...
Was there a spark when you connected the 2nd terminal to the new battery?
Is the interior light stuck on?
When you put the charger on it, do any lights come on? How much current is it pulling

MileHightC

You can take it to an auto parts store and most of them will do a charging system test for you...if it died overnight I would say you've got a pretty significant draw coming from somewhere that you're going to have to chase down.

Will the new battery take a charge?

Any other info on the car...aftermarket alarm, other additions to the electrical system, etc. You can put a meter on it and see if it's pulling a charge even when the cars off...that'll be what you need to find and you can narrow it down by pulling one fuse at a time to see which one makes it go away. Chasing electrical is never fun.

Big_Jim

iTrader: (3)

Did you drive it after replacing the battery and starting it up?

I'd take the alternator to get tested at your local parts shop.

RichBinAZ

Doing the quote may help the OP find it

As Big Jim says, your alternator may have failed if none of the other items are the culprit
If you can get the engine started, you should be able to measure 14V at the battery with a working alternator. If it's just 12.x Volts, then the alternator is not charging. Check at stays at 14V by reving the engine to 2-3000 rpm.

Something I didn't know existed were alternator rebuild kits ___https://www.maniacelectricmotors.com/nsearch.html?#search/q=scion%20xb%20&sortby=rel&page=1&size=15&storeid=yhst-44365514171686/1___
A lot of places sell these kits and if the stator and rotors are fine, you can just replace the regulator for a lot less than a new/rebuilt alternator