From o2 sensor to engine replacement in 10 days?

The chargers are usually multi purpose now, AGM battery setting will automatically be around 4A - 10A.

The charger you referenced above works and is only $29.99 at walmart. It charges at 3A but for what you need it for, it'll work. Just takes longer. When fully charged 12.9+ volts, your battery should be able to hold a charge of at least 12.4+ volts overnight (not being charged). If it can't hold that charge, it'll soon fail.

 

You can get started right away with the charger you have now. I don't think it's the best unit for what you need done, but I do see a lot of value in having it right there and paid for right now. And by "not the best unit" I mean maybe you wait a bit longer. It doesn't really diminish your overall chance of success.

 

Your battery might just need to be charged now because you keep opening doors, starting the car, having interior lights on.....all that stuff will drain it. Normally you won't do all that stuff to drain your battery.

I think once it's fully charged, it'll be OK

 

I would be very worried, and wouldn't drive the vehicle (much less start it) until you have this electrical issue sorted out. That area around the 12v battery is where the warm air exits from the HV battery before going out the passenger wheel well. You need to tear apart the hatch area and look for any tell tale signs of this burning electrical smell, and if seeing none you should take off the HV battery cover and look at the wiring harness.

There are better 'how to" threads and videos out there, but here is a trim removal guide with decent hi-res pictures, it will give you an idea of how easy it is to remove all of the bits: 2004 - 2009 Toyota Prius Plug-and-Play Car Harness Installation Instructions

Once you have a 12v source attached you can roll down a window, then continue charging from there.

 

If there are fumes coming from the battery, you should stop charging it. Get a new one

 

Should be ok, but try to take care of the window before the engine auto-starts in about 7-10 seconds, then turn it off again.

You could also remove the 12v battery and charge it outside of the vehicle. If you remove the 12v source from the vehicle, be sure to place something over or into the latch mechanism for the hatch, else it will lock and then someone will need to climb over the backseat to remove way to much stuff to get at and pull the interior hatch release lever.

 

You have a bad cell in your battery, stop charging it. Get a new one

It takes hours (overnight) to go from 8v to 12.2v. You did it in a very short time. That battery is toast

 

Bosch and optima are both good enough, get whatever is cheaper

 

Which retailers are local to you?

 

I agree jc, it sounds like a dead cell. I had one a couple of years ago with a dead cell. I had it on the charger and checked the voltage right away and the voltage was dropping while I was watching it. It wasn't even attached to anything. Took it back to Sam's Club and the guy said it had a dead cell.

I understand Pep Boys sells a battery made by I believe Exile someone talked about.

Take your old battery with you for the core charge.

 

Charge your new battery before you install it. If you already installed it, you can still charge it until it's full before using it

 

Autozone should have a 20% off coupon (online). Some of the batteries they carry are Johnson Controls Inc products.

Pep Boys also has an online coupon for 25% off (every little bit helps). They sell Champion AGM batteries, which is a JCI product with a 4 year warranty.

Many of those retailers price-match, find a common quality battery and call around if needed.