Hot traction battery

i would get oem plugs from a dealer because of the proliferation of chinese fakes.

the battery is likely weak and in need of replacement because of all the old cells

 

The temps and fan speeds may be normal, within specs.

 

Is 120° seriously warm for the traction battery that many sales that many amp hours battery chemistry and all that I'm just asking it seems awfully low 120 that's like just above the temperature of outside in a lot of places in the USA It just seems to me like it would be more like 1:30 140ish I mean anything can run at those temperatures that's nothing I mean it might be to a human being but the plastics and battery and electricity I would think $140° wouldn't be squat what is my big fancy wire for my hot tub rated 90° C what is that I don't know the conversion that quick that's like 180° or something? I don't know It just seems awfully low 120 seems really I don't know like I wouldn't be worried about it when I touch my battery pack every so often in the back of the car it's a tad warmer than I am or I wouldn't feel the heat right But nothing that makes me think anything no smells nothing happening that's what I go by when things don't smell right electricity gets warm enough you start getting that ozone smell

 

It wouldn't hurt to verify that the duct work around the HV battery is put together correctly. Maybe pull off the very last piece, the one that goes in front of the auxiliary battery to the side of the car and verify that it is blowing hot air out at a reasonable rate. Poke the little flaps in the side of the car which are suppose to blow open to verify that nothing has glued them shut.

Do you have a laser thermometer? It might be interesting to pull everything out of the trunk, drive the car around until the HV reads hot, then take a quick set of temperature readings down the side of the battery. If something inside is heating up abnormally then you might see a hot spot which is averaging out to "too hot" as the heat spreads across the battery, but is actually a bigger problem (as in, way too hot at that location.) The laser thermometer can be done safely with the car running. If you don't have one turn the car off and I guess just use your hand to quickly feel along the side of the battery. But if there really is something way too hot burning yourself is a possibility with that method.

 

I once logged the HV battery fan speed and battery temperatures while driving over a few mountain passes, and this is what I came up with:

HV Battery Fan Speed Transition Temperatures
2007 Toyota Prius
Extrapolated from OBD logger data
Approximate reading of highest temperature sensor

0 to 1 @ 36° C
1 to 0 @ 34° C

1 to 2 @ 39° C
2 to 1 @ 37° C

2 to 3 @ 42 °C
3 to 2 @ 40 °C

3 to 4 @ 50° C
4 to 3 @ 48° C

4 to 5 @ 52° C (reduced battery current limit)
5 to 4 @ 50° C

5 to 6 @ 56° C
6 to 5 @ 54° C

Note that the fan speed is reduced when the battery temperature drops back down to 54°C (129°F), implying that Toyota engineers considered that temperature to be safe enough that maximum fan speed is no longer necessary.

 

I wonder if the transitions are purely triggered by the temperature or if there is also a time component. That is, it drops down a speed instantaneously at 50C, but if it then sits there (like at 49.5C) for so many minutes maybe it goes back up again? 50C might be fine for 2 or 3 minutes, maybe not so much for 30 minutes.

 

The fuel filter never clogs. Some of the fuel pumps are known to seize. The fuel pump filter and sensor assembly is about $800 as a kit. The only way you can replace the parts separately is to read the part number off the Mitsubishi fuel pump and order it on eBay and then change the connectors. But this is not your problem that you are experiencing. The pressure is fine if you don't have any codes. You are running techstream to perform all diagnostics right?

Aside: I need a new OBD dongle. Which do you guys recommend?

 

The traction battery fan is venting at the right rear corner by the 12 volt accessory battery. I guess they didn't want to recirculate that into the cabin. There are noxious gases from it so running the fan at high speed does waste air conditioning. I can kind of see their point. However I would like to see the fan speed slightly higher to allow full region braking. Is that the best balance given this concern?

 

There is probably a way to crank up the fan, but keep in mind that the faster it spins, the faster it is going to wear out. One from a junk yard will be just as old (more or less) as the one you would be replacing. A new OEM one has an MSRP of $444 (but is available for $333 at a dealer near me.) Not cheap. Dorman sells one for $228, maybe it is OK? Not a huge fan (joke!) of that brand - OK for chunks of plastic, metal, and rubber, don't trust them much for anything more complicated.

Can't just change the motor on the fan because the cage is more or less permanently attached to the shaft. Molded on or pressed on, I can't tell which.

 

Attempted to use Dr Prius today in the cheap Chinese crap that I plugged into my car made the car throw codes. As if I already didn't have any faith in cheap Chinese crap already this really put icing on the cake. So I took a sledgehammer to the Chinese crap and put it in its place. It's probably spyware from the government of China Just like tick tock anyway

 

For basic stuff like Dr Prius I use the BAFX products device (bluetooth version with my android phone).

Posted via the PriusChat mobile app.

 

Absolutely. I didn't bring that up as a possibility because hardly anybody has access to that technology. (Just looked and these devices have come down quite a bit in price. Still, the least expensive ones are still around $200, and who knows how good those are.)

 

From what I can tell from my logs, which I usually set to record every ten seconds, the fan speed transitions are within a few seconds of reaching the battery temperature transition points. When the fan transitions to the next higher speed, it continues to run at that speed until it cools two degrees Celsius below the temperature where it sped up. So for all practical purposes, the transitions are purely triggered by the temperature and there is no time component.

At 50°C the fan speeds up from speed 3 to speed 4, and doesn't go back down to speed 3 until the temperature goes back down to 48°C. Then the fan speed will not go up to 4 again until the temperature goes back up to 50°C again.

 

I think it's probably the best balance for the average driving profile and average climate. But, if under your specific conditions, you are missing out on a considerable amount of regen braking due to high battery temperatures, then a higher fan speed might be the better balance for you.