hybrid battery failure? Or?

Yeah that's awfully low mileage things don't sound correct to me either but leaving these car for months things like this do go on maybe you want to get a trickle charger at 300 volts DC on the battery for about an hour and see how long it takes to get to a level where it doesn't change for 5 minutes is generally the recommendation I think. I mean I didn't look at your location but it is remotely possible that you have bus bar and bus bar connection and nuts frosting and corroding and beginning to slow the movement of electricity as possible someone would have to look.

 

Lesson learned: Get someone to drive an old Prius every couple of weeks.

One module going bad will knock out the whole hybrid battery. They age on time as well as miles. Most likely it is bad but the question is can a specialist tear it apart and replace bad modules? Even if they do the battery is old. However a new set of battery modules installed can be had for $2400 or less. Just not at a dealer who charges $150-$200 an hour and often doubles his cost on parts.

A scan tool like Car Scanner or Dr Prius with a bluetooth adapter can show you what the dealer saw using Techstream. But it won't fix it.

The short term cheap solution is one of the various "rebuilt" batteries where they have already swapped bad modules for better ones. Generally you get six months or a year before you get to do it again, maybe on questionable warranty. You are then losing reliability instead of getting new modules you don't have to think about for another ten years.

Include your city and you might get some recommendations. Or hide it.

 

Mileage does not suffer until the hv battery is 99% dead. The three month layover took one or more modules from perhaps 35% to 10% usable capacity. The apps and scanners listed above will show you module voltages but not capacity. If the car ran, Dr Prius has a guesstimate percent of capacity left. Sometimes corrosion of the buss bars is also a factor and has to be cleaned up during a teardown. What you often see with a failing hv battery is fast discharge at traffic lights with the ac on. Then the engine kicks on.

Your options are used, new or tear it down yourself and try to diy. Some dealers have a whole battery charger which could be attempted but it might be just throwing away a few hundred dollars.

 

Seem odd to me as well. Do you have another 12v you can try? If that doesn't work, try resetting the ECU.

 

if there is a code for a hybrid battery replacement, that code is usually not wrong. Dealer would not tell you that unless they get the code. It is not ODD at all to let a 10+ year old hybrid sit for a few months, just to come back to a failed battery. This is actually pretty normal

There may just be a weak module in the pack, the hybrid battery might just need a good charge. However this would just be a bandaid to what you're facing, a new hybrid battery is definitely in your near future.

In Southern California, the shop I frequent often will install a new battery from Toyota for $2500. That being said, since your car has been to the dealership and got a quote for $4300, I would recommend you contacting Toyota corporate and ask them to do a goodwill warranty on the battery. The warranty is 10years or 150k miles. You are not too far off of the years and significantly under the mileage. If you call the toll free number for Toyota corporate and ask for assistance, they may help you out with this repair.

 

Yep, the dealer is trying to scam you because Toyota never trained them on caring for battery packs when they get older becasue they make more money forcing people to buy new ones.

If they had even a shred of basic integrity they'd explain that the 28 modules in the pack have to be near exact same voltage and when they get older and sit unused for a while they self-discharge at different rates. So when you started up the car the modules are no longer the same voltage and you get warning lights.

It's an easy fix though... You just hook the hybrid battery pack up to a high voltage trickle charger to re-charge and re-balance the pack. Maxx Volts and Hybrid Automotive sell these chargers, but they're over-priced. Or you can build your own charger for $100: Build Hybrid Battery Maintenance Gear For Under $100 | PriusChat