Battery unable to hold charge -- 2008 Prius

Holy Christ You see the red light with the red post of the battery with the white on it connected to it and the red post or the red terminal should be connected to the red post That's telling you your battery terminals from the battery charger are connected to the wrong terminals on the battery Red needs to go to plus which is the big red thing on your battery in the back holy Jesus but you're not charging back there so on the red part in the front under the fuse box there's a red slot that you have to lift a cap on That's your positive then your negative is going to go to a big bolt on the engine or on the strut tower or somewhere but that's a terrible place to connect usually it just overheats your charger and creates a bunch of doo doo You need to go to the back of the car lift up the silly tray lift up the black tray now you can lift up the right side carpeted piece of trim that will expose your battery now put the red battery clamp up near the red cover which is the plus terminal of the battery and you can put the black terminal from the charger on the other post which is negative now the red light is not on on your charger. And it should be starting to charge your battery there should be an amber light on during charging then after so many hours that Amber light will turn off in a green one will come on which is on in the picture I think if the text under that light tells you after it no longer amber and it turns green then it's in the maintaining mode. I have the same charger but mine is a 100 20 10 or something like that. Same manufacturer almost the same lights just a little bit heavier duty but the same case. What you got going on here is nothing your battery is not even getting a charge because the red light is on and the terminals are reversed put them on at the battery in the back of the car. It's in the right side of the trunk when you're standing in front of the trunk right in the corner just under the tail light your high voltage battery is also in the back of the car it runs right behind the back seats but that's for another day.

 

what are you studying in college?

 

jump start it and take it to auto zone for a free load test

 

Buy a cheap digital voltmeter or borrow one from an electrical engineering student. Before you shut off the car leave the hood unlatched (but mostly closed). The next day open the hood and prop it up. Open the fuse box on the drivers side (push in on the latch at the front and lift up, the back end of the lid just has slots that hook on little arrow shaped tabs on the box - pull up on the back too hard and those tabs will break). Put the voltmeter on "DC voltage", and if it has a range, pick one that includes 12V. Flip up the little cover where the big cable comes up the side of the fuse box, it is on the left side as you face it from the front of the car. Put the positive lead of the voltmeter on the jump post (the big copper tab that sticks up where the fat cable goes into the fuse box. Put the negative lead on a clean bolt, like the ones around the edge of the inverter (the big metal box just to the left of the fuse box). Be sure that you are holding the plastic parts of the leads, not the metal ones. It should read over 12V. If a buddy turns on the car while you are reading the voltmeter the voltage should jump up to something like 14V once the car starts. If the battery was horrendously bad and the car doesn't start it might fall below 10V.

Note that if a 2nd Generation Prius isn't driven on enough long trips it will eventually kill the 12V battery. Since you received the vehicle from a grandparent it may be that it was not being driven very much and the battery is now bad, even though it is only 3 years old. You can get an OEM battery at a Toyota dealer, but Walmart also sells a compatible battery which seems to be of good quality. This is an AGM battery in an unusual size. It is easy to replace the 12V, but since you don't sound very comfortable working on cars, maybe have a friend who is more into this sort of work help you. Also note that there is a little tube that needs to be plugged into the battery, it is a vent to move any bad gasses out of the car in case the battery has a problem.

Once you get this fixed (whatever it turns out to be) make a point of driving the car for at least 20 minutes straight once a week, and not making many short trips (<5 minutes, <5 miles) in between. Technically you don't have to actually drive it, just leaving it on in Ready mode will charge the 12V. I don't suggest leaving it unattended in that mode though. One way or the other you will need 20 minutes of seat time. You could put it on a battery minder, but few college students are in housing situations where that is going to be practical.

 

After screwing up not only the fusible link but other electrical things, I learned the Gen 2 Prius AGM battery doesn't want more than a four-amp charger and a ten-hour charge. Your Prius is not your regular old car that you can just charge or jump with anything.

 

If the cover comes off easily open it op (not plugged in of course) and blow it dry with warm (not hot) air from a hair dryer. But don't touch any of the circuitry as there might be a capacitor in there charged to 180V. It is probably just a single sided circuit board inside.

Mine is a 4A Viking from Harbor Freight, and it doesn't have any ventilation holes. So any water that soaked in is going to stay there for a very long time. It appears to be held together by 4 Allen head bolts (or screws) at the corners. That sort of construction is probably pretty common for low end chargers.

I also have a Battery Tender Jr., and while it does have some small ventilation slits they are not enough to see in and determine if it is dry, or to get much warm air in. It is held together with 3 bolts (or screws).

 

sounds like the battery is toast. you can pick up a new one and diy, there are youtube videos

 

What wasn’t charging, 12v or hybrid battery?

 

Correct. Start by replacing the 12v (how old is it?)
Then you can check for trouble codes for the engine light

 

I see the battery is 3 years, you can try charging it up by jumping and leaving it ready for 8 hours, or get a charger.
Check into the warranty