12 volt battery issue

I assume it's the original battery? If so, it's given up the ghost and best bet is to replace it. I'm surprised your auto store didn't give you a price for a new battery, they should have one and even offer to replace it for you. (O'Reillys and Auto Zone will.)
But you do NOT want to be driving around on a bad battery so I'd suggest replacing it. Cheapest option would probably be a Walmart Auto Center but shop around, sometimes you can find sales.

 

It's not a special battery it's a special size and it has the funny posts on top that accept the small posts of your connectors in your car other than that nothing really going on I think now they're 415 cca and that's about it Yes you can put a charger to your AGM battery or regular 12 volt battery You can watch it charge on your charger to see if it turns green or whatever the charger does to indicate the battery's good If it takes two days to get there the battery is probably bad If it never gets there the battery is probably bad If the light on the charger tells you s u l or something along those lines the battery's bad get a new one how much about 160 to $189 maybe upwards of 240 depending upon where you shop You're looking for an advanced glass mat battery and this size range whatever they tell you the Prius is it's a funny number You don't want to get into alternative batteries or any of that yet just get the regular battery A diehard in the blue color on it is a good choice I have a few of them they've done pretty well

 

The AGM battery you buy from Sears or wherever we'll have a little hole on the side when you flip it around to drop it in the Prius you'll see where your little plastic 90 is supposed to push into the battery If it doesn't have it it's sealed and doesn't need it You continue installing My latest '08 car with the hybrid battery replacement doesn't have the vent tubes on the battery modules so it doesn't get the vent tubes or the vent outside of the vehicle connected because like the later model batteries in the generation 3 it doesn't need the vent tubes Yes we're discussing two different batteries but basically talking about the vent tubes that can go away with later model batteries

 

You need to get another AGM battery, yes. AGM will have the vent tube. They are a bit spendy but the new one will probably give you another 10 years.

 

The battery should have a vent port close to the positive terminal. The vent tube stays with the car and plugs into the port on the battery.

 

start with a few dealers, it's usually competitive. you can search online for auto supply places that carry them.
get the vent tube for safety, unless it doesn't matter to you.
some don't care, and even install $50. lawn tractor batteries

 

A 4 amp or less AGM charger will work.
But since your battery is dead, let it rest in peace, and get another Toyota battery.
Then charge it at 4 amps or less for about 8 hours.
No place charge the batterys and they discharge over time.

 

Yes, of course. Owners Manual says to disconnect battery before charging. I’ve always charged ours in the car, connected. I’m using a CTEK 4.3 smart charger; believe the current equivalent is CTEK 5. I installed the quick connect harness (came with the charger), and with our low usage keep it connected near-constantly.