Car won’t start.

Normally it won't.
It sounds to me VERY much like your HV battery has finally failed.

Either you need to spend a couple of hours reading back threads about testing HV batteries and buy a multi-meter.......
OR you need to have it towed to a Prius shop or hybrid battery shop.

Given the age, it might not really be worth fixing.......for the "average" owner.

 

There is no magic.
You haven't supplied near enough actual information to get back a good answer.
What about the 12 V battery ? Did you test it ??

 

SIGH.

All of that might be interesting BUT none of it means that the 12 V battery is actually GOOD.
New batteries fail, even when on a tender. The Optima's seem to do that more often than most.
And even a good battery can have a bad connection.

Good luck next spring.

 

The "test" that any charger does on the battery's health is pretty rudimentary and can't necessarily be trusted. It sometimes lies.

Then, yes, but the charger to do the HV battery with is fairly expensive and messing with it can be rather dangerous.

 

It does, inexorably, if sitting long enough, as touched on briefly in the owner's manual on page 8:



For that purpose, "a long time" is generally thought to be on the order of several weeks (I think some other years of the manual have been a little more specific than this 2002 edition, but looking up other examples feels like work right now). Hence recommendations on PriusChat to arrange for somebody to start the car and leave it READY for a few minutes now and then, if it is going to be stored a couple months or more.

I re-read your post looking for how long the car had initially been sitting, but I've missed it.

What you thought first was correct, and then you talked yourself out of it. The car will run the engine as needed and recharge the hybrid battery any time the READY light is on (and the transmission is not in N). It can be sitting there in P, up on blocks, while you read a newspaper, cut the grass, whatever, and it will charge the battery if the battery needs charging.

Do you happen to remember what the battery charge bar graph on the MFD looked like at any of those times?

My reading would be that the battery was quite discharged to begin with, but still able to start the engine, and after that the car was busy doing what it's built to do, running the engine to recharge the battery, taking longer because of the severe discharge. I would have left it running longer (yes, I know hindsight's 20/20) and watched to see if the bar graph was going up. If it ran for quite a long time without the bar going up, or there were other warning lights on at the time, I might have tried a scan tool to get battery condition and any diagnostic codes while it was still running.

Again, you don't need to drive it to charge the hybrid battery, but you do need to get the engine to start, and it will charge as long as it's sitting there, if the battery is still viable and able to take a charge.

As long as the 12 volt battery is good and you can turn the car ON (just the key to ON position, not start), you will be able to use a Prius-capable scan tool and learn the car's exact reason(s) for not starting the engine now, and also a lot of info on the condition of the battery. That would reveal whether the battery is damaged, and how severely, and whether the damage is throughout, or limited to a few modules.

If it needs to be charged to a minimum level to start the engine (and if it can be), that's a bit of a process. Toyota has hybrid battery charging equipment, but not normally at the dealer; it has to be shipped there, sometimes along with the person who operates it.

There are products called "grid chargers" used by some on PriusChat with the aim of extending the life of the hybrid battery, and those can also be pressed into service to charge a severely drained battery (again, if it is chargeable). They have to be installed, which shouldn't be attempted lightly with just some electrical knowledge and a DVM, but rather with the right personal protective gear and an informed respect for what, in a Gen 1, can exceed 300 volts DC.

Again, the information from a scan tool on the trouble codes and the battery module condition would be what I'd want in front of me before choosing a way forward.

Edit: Gen 1 cars have also been caught doing a sort of battery-balance cycle now and then, where instead of stopping charge at the usual target of 60%, they will push it right to 100% and hold for a while, then let it discharge back to 60%. My old Gen 1 used to do that a couple times a year at least, usually while I was driving and probably wouldn't have noticed without a ScanGauge to watch. If the car had been sitting a long time, the battery might have been in a condition to trigger that cycle, which would be another way to explain the unusually long run time.

Also, are you sure the engine hadn't cycled off while you were half an acre in, and happened to cycle back on when you came to look at it?