MG Hanging Up???

Well given that recently implies during cold weather (I assume it's pretty cold in Pa this time of year) then yeah, the battery fan must be well clogged for sure.

A few years ago I started noticing my battery fan often running high in summer so I took it apart and checked it, and it was pretty clogged. The was the first time it had ever been cleaned,but now it's something that I do as part of regular maintenance around every 18 months.

 

It can be tested, but it is tricky and often inconclusive. Lack of any warning lights or pending DTCs make it difficult with the tools and procedures that are available to a dealership tech. Read the following thread for a cautionary tale on the difficulties that Toyota has with weak hybrid battery diagnosis. http://priuschat.com/forums/gen-ii-prius-main-forum/95641-power-loss-low-battery-during-climb.html

The only reason to have it tested would be if you are nearing warranty expiration for the hybrid battery -- 8 years/100,000 miles in your case, unless you purchased an extended warranty. If it is out of warranty, I suggest keep driving it but start looking for one from a recent late model wreck. Any service provided by the dealer will be much more expensive than if you do it yourself or pay an independent shop to do the work. If it fails, the car will still move (forward only), but will be in a limp-home mode, similar to a car with a bad automatic transmission. Battery replacement is an interior job comparable to installing a car stereo, only heavier.

 

Thanks - I will be sure to deal with that esp. since its an easy action to take. (FWIW - no dogs or kids in back seat ever in car, garage kept, keep it clean, etc. but...)

Re: your other question, and in partial response to Tom,
actually we see far less swings in the SoC indicator. It stays at 2 or 1 bar down from full maybe 90% of the time, occasionally shows full or 3 bars down. That's it. Our memory of earlier years is that we would see much greater swings and that the average SoC was less than it seems to be now. Our driving routes and patterns have not changed.

 

Indeed we are out of warranty as of a few days ago. No extended coverage. That's why we tried to get a dealer to acknowledge this issue earlier in case we might be covered. No luck.

Are we still talking about the HV battery pack!!! I had been told that replacing them was a dangerous job akin to handling fuel rods at a nuclear power plant! Danger, danger - ultra-qualified techs only. Really?

I should also mention what happened at the last visit to the dealer shop. Supposedly I got the shop foreman with Toyota Master Tech qualifications; we took 2 test drives together. He was skeptical that there was anything amiss but the car did slow abnormally down a large hill. Afterwards he did find a "code" - an "ABS/TRAC code C1241 - 81" "Excessive high or Low Battery Voltage". During a drive that he took alone, he recalibrated the linear valve offset/stroke sensor (whatever the heck that is) and then performed a zero point calibration. We test drove again together and it seemed that the car was behaving closer to normal. As I keep noting though, it is oh so hard to replicate this problem or have 2 test drives be identical in all parameters. I left with fingers crossed. I had the worst case of this odd "B mode" braking occur about a week later. My phone call back to them did not result in anything useful.

 

Ok, another good test of the traction battery is just how well it can actually hold EV mode. If the battery voltage or resistance is poor or it's temperature too high then the controller senses this and kicks you out of glide (electric only) mode. So with a bad battery the engine runs pretty much all the time, whereas with a good battery it cuts in and out more often, especially at speeds below 42 MPH.

Is your Prius still able "glide" at speeds below 42 MPH? Try this test. Find a nice quiet flat piece of road and turn off all accessories and A/C heat etc. Then accelerate to about 30 MPH and then lift your foot from the gas pedal and then really gently re-apply it. The car should go into full electric propulsion (Ev mode or gliding some people call it).

Say you start this with 6 or 7 bars of SoC then as long as the road is flat and that you don't try to accelerate (just use real gentle pressure on the pedal to keep the const 30 MPH speed) then if the battery is "ok" you should easily go about 1/2 a mile like this without the engine starting.

EDIT: If you want to try that test then you might be better to start the "glide" at 35 to 36 MPH to avoid the cursed stage3b/stage4 thing. (Unless you already know how to put it into stage4 before starting the test.)

 

I'll give it a try. Thks

 

I saw the same with my 2006 for awhile. I thought I might be having a problem. I first noticed it while highway driving, and it caused me some concern. Once off the highway in normal conditions the SoC behaved normally. It seems to be fine. I think I fixated on a perceived problem and was borrowing trouble.

Tom

 

Just saw your edit, I may need to try again. I'm sorry but I have no clue as to the stage3b/stage4 thing.

I did try the test, several times, at about 30mph. It's pretty hard to find a truly flat road around here and it's pretty windy today as well, so too many uncontrolled variables for me to draw a lot from this. That said, my results were inconclusive at best. One test, the ICE remained off except for 1 brief second. Hmm. Most of the tests, the ICE came on/off charging the battery and/or driving the wheels. A few tests, the ICE remained on essentially the whole time. In ALL cases the battery indication was 7 bars, never budged.

 

See http://techno-fandom.org/~hobbit/cars/five-stages.txt

Basically once you've got the prius fully warmed up the engine wont cut out when you glide, unless you start the glide from 35 MPH or more (yes I know it's stupid). If you start from 34 MPH or below it thinks you might be stopping, and it wants run an "idle check", so it keeps the engine idling. The way to get it into stage4 (full hybid mode) is to do this and stop for about 10 seconds, which allows it to perform it's idle check. After being stopped for about 5 to 10 seconds it will cut out the engine and after that you'll be in hybrid stage4. After that the engine will cut out more freely when gliding.

 

Any updates? Sounds like a similar issue to my 2008 Prius. I have a new 12V that I am going to install any day (as soon as gets warmer out.

 

I explain my problem in this post
Huge Drop In MPG | PriusChat

 

An update on my 2004: At the risk of jinxing myself, I am not aware of "the problem" occurring again. It may have once or twice last winter, after my last post, but I simply do not remember. For sure, since then and into this cold winter, no problems (so far). Perhaps interestingly based on your comment about the 12V and after reading that thread, I replaced the 12V last summer (it failed completely one day and the car was simply dead to everything). That may be the only change that has happened over the last year except for a recent 90K maintenance fest where lots of fluids and the like where flushed and replaced. I had never given any particular thought to a correlation as no one here on this thread mentioned the 12V.

 

i think tom mentioned it in post #13.

 

these problem posts and then wait a year to respond to solutions amaze me.

 

Sorry about that - I did not go back a re-read all the thread. Apologies.

 

I was only responding to the other individuals request for an update on my situation. By no means was I waiting a year to respond to potential solutions. That would be rude.

 

thanks for updating us everyone!