HV Battery Above 134F !

Check the HV Battery cooling fan and see if it is plugged with dog hair, etc.

 

The highest I've seen is 115 deg F. That was under sim conditions: driving on a hot day, then park and sit In hot sun for maybe 30 min, then drive again. Seems like worst scenario. My fan is clean, I'm monitoring it periodically, fwiw.

 

Torque App from Android and Battery Temperatures

I just purchased the Torque app for Android to go with the mini bluetooth dongle I bought from Amazon for $12 and I'm really amazed at all the information available to us! I've owned this Prius now for over 3 months and have done all the catch up maintenance to it, but I was really interested especially in the battery life, and the battery temperatures. Torque showed that the middle battery (the hottest one) creeped up to 122 degrees by the time I got home (which is down a long hill that charges the battery to full) and outside was about 80 degrees (Hawaii weather). I parked my car and what surprised me was that the battery fan never engaged past 1 even though the temperatures were reading as they were (which seem on the high side from past postings I've read)

Things heat up....

I went back to my car about 90 minutes later and turned on the car so I could use my new VIAIR compressor (which is AWESOME) to pump up all the tires when I heard the back fan going on high. I turned on my phone and started up the Torque app and the temperature of the hottest sensor on the battery now read 132 degrees. So from sitting in 80 degree weather in the shade the battery magically went from 122 to 132 degrees on its own! SOC was about 70 percent when I parked.

It was really interesting to me how the fan went from level 1 earlier to level 5 (fastest?) later. It seems that thanks to Torque I had better clean out my battery fan in the back of the car, because watching the temperatures while driving, it seems the fan hasn't really been lowering very much temperature back there.

I had heard that if you turn your car A/C on fresh instead of recirculate that it will drop the intake temperature for the battery fan. I found this to be really fun to watch on the Torque app as the 91 degree battery intake air slowly dropped a degree every minute or so until it had dropped 4 degrees. Again, I'm really glad to have this tool because it is so easy to monitor the health of the whole system collectively. Ok, I'm going to go clean out my battery fan now.....

 

OK, Just had a nice two hours of fun. Got to the battery fan and found out that......it probably has never been cleaned before! So I cleaned it up. And interestingly there looked to be some duct work missing....a piece perhaps that connects that outside vent to the inside pipe? I just happened to have a roll of duct tape nearby......

We shall see what readings I get from Torque next drive tomorrow. Hopefully the cleanup job will make a big difference in battery temperature.

 

With our 3rd gen there is solid ductwork from the back seat vent to the fan, and into the battery. Coming out of the battery there's a short piece that just directs air into the space above the spare tire and tools, and that's all. It's up to the air to wander around, find it's way over to the exit flaps.

Come to think of it, a lot like Vancouver's YVR airport.

Just for your info, the highest temps I've seen for battery temp (reading the middle sensor, #2, with Scangauge) was around 46C, converts to 115F. With that temp the fan was running at speed 4, out of 5 or 6, I'm not quite sure how many speeds there are.

 

I might add to this, my 2004 Prius quit on a hot, mountain grade in the Sierra Nevada. Triangle of Death with hybrid damage possible, imminent. After a $300 tow to Toyota, they found the battery cooling fan full of dog hair and other crap. After the technician cleaned the fan out, cleared the thrown error, runs fine. $250 later, lesson learned. Not bad after 12 yrs. of dogs riding in the backseat.

 

They should make the fan more readily accessible, AND include it in the specified maintenance.