Not Starting - 2008 Toyota Prius

How do you know the hybrid battery is dead what does it show in the display in the energy mode are you looking at red bars or blue If no one's tried to start this car for a year I would expect it to be showing blue unless it was parked after ridden hard which wouldn't surprise me. So if that's truly the case and all of that then you need somebody that has a charger capable of producing like 300 volts DC at 2.4 amps very low amps and give it a couple of hours of that when you see the meter on the charger not make a change in the voltage that it's showing for the battery in 5 minutes it's time to disconnect the charger that should put you at about 2:30 2:40ish for voltage

 

is the car making 'ready'? if so, you can read the trouble codes to see what it is reporting.
if not, check the 12v and connections. make sure the brake lights come on when you step on the pedal before pushing the power button.

 

If you have a "dumb" 12v trickle charger (it doesn't look for voltage to turn on the charging and doesn't sense battery voltage and stop charging) put it across the first pr of modules, when they reach 16v, move on to the next pr ..... this will tell you if the battery will simply recharge or it has dead modules.

T1 Terry

 

The gas is also a year old. If you are lucky and the tank is nearly empty then you can add a couple of gallons of fresh gas and it should be "good gas" even if the old gas was in rough shape. Not saying the gas in the car won't work, just that it is questionable.

Does the OP own a decent scan tool? If the car can get to READY using the good 12V the voltage on the HV battery should be checked, and it would be wise to check for any error codes.

Don't just keep trying to start it. It won't make anything better and it could make things worse.

Also, why wasn't the car driven for a year? Was it not used because it was having problems?

We don't know where the car was stored. It would be a good idea to open up the air filter box and make sure that it has a good air filter and not a mass of ripped up fibers and a collection of rodents and/or a collection of nuts.

 

So many variables. Let's eliminate one. Before it was parked for a year, the car would start normally?

It sounds like you need to get the HV battery charged. Given your location, perhaps there is some mobile mechanic you can call who has the equipment to do this? I know the guys who sell rebuilt HV batteries will come to you, and they probably have the right equipment to charge the battery, but I don't know that they will bring that to you to charge your battery, and I'm not sure I would trust a lot of them not to do the "this battery is fried you need a new one" routine, when the battery is actually still good.

Edit: Since your location is New York city - do you have a covered space with power where you can work?