Dead Hybrid battery? Look for the root cause..

WOW, yuck. This was brought up in the dog proofing thread to cover the vent with screen or something to prevent all the dog fur from getting in. I still haven't had a chance to do it, but I should check it anyway since the last owner had a dog too.

Thanks for the post! Thoroughly grossed out and motivated to clean mine out!

Now I'm really nervous though because the last owner had the battery replaced at 80,000 miles and it's about at 82,000 ... I'm thinking that could be why...

 

Good post ovni. I also had battery overheating problems in the first summer that we got the Prius. It was secondhand and I guess the previous owner must have had something in there to let it clog up. Here's what it looked like when I pulled it out to check.



I check mine about every 18 months now, and clean it up as needed. Probably only a 45 minute job once you've done it once. Most dealers seem to be oblivious to this issue.

 

Any update on how to safely get into the fan to get it cleaned out. Now I'm no longer using mine as a taxi I intend keeping it and do want to check the fan.

 

Wow this is gross! I am assuming you are referring to one of the engine cell batteries and not the 12 volt battery? I will be interested in knowing how much the mileage improves.

 

GC, it's quite easy and safe to remove the HV battery cooling fan. You do not get anywhere near to the high voltage section of the battery, only the cooling duct. The fan motor is only 12 volts and is isolated without the key fob in the car. Just a matter of removing trim on the right hand side of the boot to gain access.

John (Britprius)

 

IMHO, this is a failure in programming and/or service manual. It should be simple for battery computer to figure out that battery is not cooled efficiently and produce a code that defaults to checking the fan. I lot of good batteries were lost/replaced at a great cost and bad reputation due to this neglected fan issue.

 

Yep I totally agree jacek. Living in a fairly warm-hot climate here I find the battery cooling to be a definite weak point in the Prius design. At just over 100k miles I'm out of warranty and with a HV battery that's been overheated several times (rear fan running flat out and hot enough to cause driveabilty issues like high engine revs and lack of EV power), it's already showing definite signs of loss of capacity and "sudden loss of bars" under some driving conditions. My battery is still hanging in there, but I'm certain it would currently be in a far healthier state had it received proper cooling over it's life time.

Personally I think they should have routed a special duct straight from the air-conditioner to the rear battery and even forced the AC on when the battery required it (even if the user had no AC selected for the cabin, a small amount of cold air cold still be shunted off to the batteries). This would also ease the problem of the pack picking up hair and muck from the vent that can get around the cells and inhibit cooling, given that the AC air already goes through the cabin filter.

 

It's which parts of trim to remove. I'm a butcher when it comes to such matters and would rather know which of the five bolts or screws I need to undo otherwise I'll end up with seven left over.

 

Yep I'm the same Grumpy, but even I managed to get it off without breaking anything. Here's a photo I took of mine while I had the trim removed, I've even labeled some of the stuff to make it easy to identify.

There are two or three phillips head screws to remove and everything else just pops out. Just have a wide flat blade screw-driver (or even a butter knife) and as you try to pull the trim away you'll feel where the fasteners are and then just slip the blade behind and pop them out.

 

I tucked a piece of vacuum motor filter material on the inside of the fan intake grill on ours, soon after purchase, a bit over two years back. Just happened to check it yesterday (I've checked it once before). You could see a faint dirt imprint at the grill opening portion, and there was a few seeds/burrs. Vacuumed and blew it out and re-installed.

Obviously the pics above someone was transporting a pet of some sort. And more frequent checks of a filter would be needed. Either way a filter seems to me good insurance. There's the concern it might reduce flow, but at least you can see the clogging, right at the inlet.

I did something similar with our house's forced air system, replaced the bare air intake grills with grills that hold filters. They pick up an amazing amount of dust/lint, and the main filter at the furnace is more-or-less pristine. I also tightened all the duct circuits, to ensure the intake air is largely coming through the intakes, not seeping in along the circuit.

 

i wonder if foam would be best? i wouldn't want to slow air flow with paper or something similar.

 

The Dyson type of pad filter media should give really good air flow and excellent filtration.

John (Britprius)

 

you mean for household hvac?

 

I agree. You can monitor all of the battery fan variables and battery temps with ScanGauge so the computer has all of the info. I cannot imagine why Toyota does not alarm on this.

One more reason to use some type of OBDII device to monitor your car more thoroughly.

I just checked my battery fan out today while testing an inverter. Mine was spotless after three years. Of course I have never had a pet in my car that can shed.

 

I just had a look at my fan. With only ~35K miles, and no dog, it still needed cleaning. Not as bad as the cases above, but I'm glad I got in there and blew it clean again. No problem to take everything apart, so I recommend for anyone to just have a look, and see what you find. Tools are a 10mm socket and a Phillips head screw driver. A wide thin screw driver can be used to pry the plastic bits out. The plastic clips with the small pin in the middle can be removed by grabbing that center pin with a needle nose plier and pulling out.