Hybrid battery failure@154,000 miles, California

Not bad at all for a new HV battery plus labor. I would thank Toyota for their act of goodwill. How long did the whole process take, start to finish?

LG G3 T-MOBILE phone ☎

 

Congratulations! You stayed on top of the situation until you got a fair deal from Toyota.

The individual Toyota dealers sure are all over the place when it comes to how well they treat Prius owners. It's a relief to hear that Toyota corporate still feels some love for us folks who have owned a Prius for 10+ years.

When the HV battery in my 2005 Prius began to throw P0A80 DTC codes 6 weeks ago I read the "DIY hybrid battery repair" threads here on Priuschat and did it myself. But then I'm a career EE and lifelong DIYer.

-EB

 

So what did you find wrong with your battery?

se

 

My HV battery had one failed module (6.6V). I also replaced one other module that tested 100mV (0.1V) lower than the others. That was 5 weeks ago. So far my car is running perfectly.

 

Did you use the 1000v linemans gloves? And did you use a Fluke meter to determine the tenth of a volt difference?

se

 

Insulating gloves are required for the initial steps of removing HV pack from car and for removing the busbars from the 28 battery modules inside the HV pack. You should also be wearing good eye/face protection and a heavy long-sleeved shirt. Ideally you should wear the same clothes that you would wear when using an arc welder. You could use a welding mask that has the optional "clear" lens so that you can see what your are doing.

There are 2 safety risks when working with the Prius HV pack:

1. Electric shock from touching a circuit that might carry 200V
2. Arc flash burns from accidentally short circuiting the HV pack while working on it. A charged HV pack can produce 20,000 watts. Shorting out a Prius HV pack is comparable to sticking a screwdriver across the main terminals of your household "grid" electrical service. It's rather scary! Believe me, you don't want to short out the HV pack output terminals! Look up "arc flash accident" on YouTube for examples of what you don't want to have happen.

But after the busbars have been removed from the HV assembly then the maximum voltage that appears anywhere is less than 10V. You do need to avoid accidentally short-circuiting individual modules (that could still make a pretty big spark and a lot of heat) but there's no high voltage after removing the busbars.

I have a bunch of meters all the way up to one with 5 1/2 digits (it can measure to 1.99999V precision). But even a low-cost meter from an auto parts store can detect the difference between 7.70 volts and 7.60 volts.

In my case the module that caused the P0A80 DTC codes was measuring only 6.60 volts (1 volt below normal).

After changing that one failed module, I then located and changed one other module that was measuring about 0.1V lower than the other 27.

I did NOT do "module balancing" because I didn't have an RC charger/discharger then. But it worked fine for me without the balancing. There have been zero DTC codes on my Prius after my DIY HV battery repair. I'm almost finished with my 3rd tank of fuel. Current tank is 43.5 mpg. That's mostly "local" driving, no long trips. Using the AC about 50% of the time.

-EB