Bad Battery or Bad Dealer?

I'm one of these guys that fixes everything myself. If there's a warranty where someone else is paying the bill well that's another story...

I have an '05 GenII with ~166k miles that has been a great car for me. I haven't had to do much work on it except change the oil (every 5k miles), the tire tires (3 times) and the 12v battery (2times). I commute about 50 mile five days a week and about another 200 or so on the weekends.

A little before the HV battery warranty was up (150k in CA) I started to notice the HV battery dropping to two bars ever so often in the mornings, down from full in the evenings so I brought it in to the dealer to have them tell me it was a bad HV battery, or so I hoped they would so I could get it replaced before the warranty was up. They diagnose it as a bad 12v battery and sold me one that I put in myself. Well the problem was still there but seeing as how it didn't seam to affect the drive-ability I just kept driving. The mileage started dropping till it got to about 38mpg so I thought I should take it back to Toyota to see what they said. This time they did diagnose it with a bad HV but by now the car was out of warranty. I asked them how they tested it to tell it was bad and they said they drove it up a hill and the battery went low fast. When I went to get the car I asked them why they didn't see this when I brought the car in under warranty and the service writer told me that there was an HV DTC code now that wasn't present the first time I brought my car in. I asked for a copy of the codes and took my car, and an estimate for over $3500 for the new battery. At home I looked up the DTCs and none of them where for an HV battery fault. I had a P1121 and a P1116, the famous three-way valve, but nothing to do with the main battery. Anyway I pursued trying to get the battery covered under warranty and talked to Toyota support but it was no use, they basically said that I procrastinated too long, over 15k out of warranty by now. (long story sorry...). So now I called the dealer and said if I'm going to pay $3,500 for a new battery I wanted a more technical test then just driving it up a hill. They said 'sure bring it back in and we'll look at the individual cells in the battery'.


Here was what the results were:
"Per service manager tech inspected battery. Shows low state of charge. Tech and service manager drove car for diagnostic report on battery. State of charge would not go above 46%. All cells at 14.91 to 15.6V. Normal range 16.5-17.5V. Service manager talked to Toyota to confirm battery is bad. Recommend replacement of battery. Estimate on last repair order."



I told the service writer that I would see the SOC above 50% all of the time in the car but he insisted that that doesn't match the display in the car.

Now, time for me to get 'edu-macated'... After I thought I knew enough to be dangerous I ordered a bluetooth OBDII adapter and borrowed one of my kids old android cell phones. I installed Torque Pro, imported some custom PIDs from Gen2 Prius: Custom PIDs for Torque (Android App) with formulas (thanks usbseawolf2000!), and proceeded to gather my information. I also looked at other information on rebuilding the battery myself but that will be in a new thread if I go that way.

Here's part of an email I sent to the dealer:
"...I have since had the car looked at by an electrical engineer who hooked up a monitor and logged the battery data, MG2 hp, HV SOC, HV highest block, HV lowest block, and all of the individual blocks. From what he concludes this dose not match at all what you and you service tech are reporting especially the SOC staying below 46%. The attached log shows that the state of charge went for 53% min to 74.5% max and that the average battery block voltage was about 16.3V with a range of 12.86 min at the highest MG2 stress and 19.46V at the highest re-gen. This test was done over a half hour drive starting in the morning at my house in Moss Landing and ending at my work in Santa Cruz (my daily commute).
From what I can make of this I am very much questioning your diagnostics of this and your conclusion of a bad battery. If you have an explanation of this please let me know or please give me your contact at Toyota so I can understand how this conclusion has been made.
I have attached the report and service copy from you and included a copy of the log report from my EE."

If you havn't guessed the EE is me but I just didn't want them to totally disqualify the information I gave them.

There are a lot of things that really bother me about these guys and other miss information they have changed or is different depending on who you talk to there. If you aren't technically inclined they guys could tell you anything and you'd have to believe this horse crap! But I hope I've gotten my point across at least.

The dealer is at this point refusing to talk about it any further and said that I should get it diagnosed elsewhere if I don't like it. I just might but I'll probobly open the HV battery area at least and look for any corrotion or maybe something that might cause it to discharge occasionally.

I should also mention that I had a bad tire on the back, dealer said nothing and it was very loud and noisy too. I just change it out and my mileage went back up to 48mpg.

Is it just me? Is the dealer and his techs so good that I'm just insulting them by event questioning their abilities? (Toyota of Santa Cruz by the way). Were they going to change my battery and then notice the tire while it was in the shop, I'd get my car back and think that the battery fixed it? Why have all of those battery codes if none of them come on when your battery is bad? And lastly, do I really have a bad battery and it's going to completely fail on me someday soon?

Thanks for reading this and let's see if this thread goes anywhere...

 

You do make some great points. With 166k miles I'm sure it is getting close but I'd realy like to squeeze every bit out of it before dropping 2k minimum to replace. While things are good at the moment I'll be keeping an eye on the temperatures and the HV cooling fan speed. I did see that someone figured out how to control the fan speed on the GenIII by adding custom PIDs from the csv sheet in Prius PHV: Custom PIDs for Torque Android App and then adding a dashboard meter to Torque to keep the fan running higher and cooling the battery more. Nothing for the GenII though. I like how you pointed out how the battery temperature could be causing the battery to recalibrate when the battery is cooler in the morning thus making it look like the battery is loosing some of the charge. I've been seeing my HV battery get to 115f, center temp probe, when I pull in for the evening but it may have been getting even hotter, I just started monitoring. And you're right about Toyota not replacing under watanty unless a DTC is set, that's exactly what they told me.

By the way my mileage didn't go right back to 48mpg after changing the bad tire, it's a little higher, 42-44 up from 38 so the tire didn't completely fix it. Maybe the battery age. so I think I'll still open the battery compartment and inspect for any leaking, corrosion, or air flow blockage.