2002 Prius won't start...

The Prius doesn't have a traditional starter powered by the 12V battery. The high voltage / traction battery (HV battery) starts the gas engine.

But the 12V is still critical to all of the systems firing up correctly.

Important question: is the HV battery the original? Or has it been replaced? Provide details if not original. (Replaced when and with what).

Yes, letting these cars sit, particularly at this age, is really bad. The batteries (12V or HV) don't like it at all.

If the HV battery is original and you're not mechanically inclined and rely on AAA, then it's time to just get rid of the car.

Otherwise, it's pretty easy to pull the 12V battery out (a 10mm wrench/socket will do it all). Do that and take it to a local shop that specializes in batteries and/or Prius and have the battery load tested. If it fails, you'll likely need to drop about $200 for a new one. Decide for yourself whether to roll those dice, install it and see what happens. If the car starts, check that your roadside assistance service is current and take it for a really long drive to "exercise" and charge up the HV battery. It doesn't have to be long in distance, just in time/miles - drive around your own block 50 times if you want to stay close to home. Coasting (foot off the gas) as much as you can is golden - all charge and no draw on the HV battery.

If this gets you going, A) think about selling the car while it still runs, or B) if you want to keep it, make sure it gets driven every couple/few days for a decent distance/time. Don't let it sit...

 

Where do you live? Maybe there is a mobile hybrid mechanic in your area, who can check fault codes, check Google. Most likely you need your HV and 12v replaced with little charging from little use, a $2000 mistake of neglect. You don't have to drive it to charge it, you have to start it and run it until it stops on it's own

 

I don't have the technical knowledge about this to speak authoritatively on the subject, but my impression with my '03 is that it doesn't keep idling until the HV battery is fully charged. Rather it seems to be programmed to shut down the ICE at some "charged enough for now" point. There was a time when mine sat too long due to a broken windshield (tree branch) and the dumb little HV battery icon (which, of course, is wildly imprecise - why can't it just display a f^&*!ng SOC number?) could still be sitting at only half and the ICE would shut down.

If anyone can provide clarity about that, I'd appreciate it.

 

No need to fret over the HV hybrid battery just yet.

The clarity IS that your 12 V battery likely is toast and nothing in the car can be depended upon if it is really weak.

If you don't feel competent enough to buy a new battery, be sure it is fully charged and install it in the car.......
then call AAA about an onsite replacement or call a dealer for a tow.

 

Don't worry, it sounds like your 12v battery bit the dust. It's a simple replacement. You just need to get the right battery. The problem is that most auto supply store employees are just plain idiots when it comes to the Prius 12v battery. It uses an AGM battery (not a flooded lead acid battery like most cars use). Start with a call to the dealership and get a quote. That will be your most expensive option. Then disconnect the current battery. You will find it in the trunk on the drivers side with a cover over it. Remove the terminals and then remove the bracket that holds the battery in place. Take the battery to an auto parts store and ask for a replacement. DON'T except a battery that has the terminals (+/-) in the opposite location as your original. If you install one with the terminals inboard the positive will short against the car body. Expect to pay $200 to $225 for a replacement. The auto parts store may have to order it for you. Make sure you compare the old to the new to see if it's the correct fit before you pay and leave the store. Install in the reverse order that you removed the battery. Turn the A/C off before you start the car the first time with the new battery. Drive around a little (30 min) and let the new battery get a charge. All should work well. My gen1 has 250k on the hybrid battery and it is still going strong so your 200k is in the OK range for several more years.

 

I have been using a $30. lawn mower batterey from wal mart with great success.