2009 Prius Base - $19k

[Matt Herring]

Well, this is where the Chevy Volt and like hybrids seek to reverse that way of driving essentially allowing complete expense of the battery before relying on gas. This is more in line with the way people drive their cars...aka...watching the gas guage to know when to fuel up.

The Prius SOC is very fickle and many factors make it go up or down quickly. I've seen my SOC go up by 30% on a heavy downhill when I have to brake for traffic. Just the same, when I was coming out of a nice EV coast my SOC plummeted by about 30% (I only did this because I had a heavy downhill following my coast and knew I was going to be braking and recharging the battery).

But, your example of the failsafe protection of the gas and/or battery engine could take place if someone ran it out of gas on a highway and then ran it out of energy. The car would just die in the middle of the road just like a regular gas engine vehicle.

There are at least 20 threads at priuschat.com about people running out of gas...and then completely draining their battery trying to get to the station or a safer place to park. There seems to be a misconception that the Prius is "magic" and because it has a battery engine it will not die. Unfortunately, this was not the case for many drivers.

[Matt Herring]

And if you needed any proof that heavy EV driving kills FE just look at my first tank with the Prius when I had no idea how it worked. 90% city driving with heavy EV produced 56.74 mpg for the tank. My recent tanks in similar city driving are more in the 60-61 mpg range now that I use less EV.

Same goes for highway driving. Over 2 tanks of all highway (over 800 miles) I pulled about 51 mpg. My previous tank of 400+ miles (200+ highway miles) was in the 60 mpg range using Super Highway Mode.

Proof is in the pudding!

[MetroMPG]

My understanding is that even the Volt will use a defined lower SOC threshold on its battery, permitting discharge only to a certain level (albeit likely a deeper one than the Prius) before the generator starts.

So the Volt engineers/drivers could theoretically face a similar situation: if the ICE runs out of fuel when in charge-sustaining mode, the batteries will still have energy in them. How much will the driver be permitted to use once the gas is completely gone?

[Matt Herring]

Interesting...my understanding of the Volt was while driving in ICE you could still drop down into EV mode (similar to Prius) but that initially all of the driving is done in EV mode until it is emptied (at 30-40 miles) and then ICE is used exclusively with minor regen to the battery from ICE driving. When I say "emptied" I mean not completely but the percent that EV mode is no longer available and ICE is engaged.

Hence, the 30-40 miles of exclusive EV before ICE kicks in. At that time, while in ICE the EV mode could be used just as the Prius as long as SOC is favorable to do so. I did not think that ICE was available until the battery was discharged...is this correct?

[Matt Herring]

I pulled my lower grill block the other day as temps were creeping towards 80 degrees. Today temps were in the mid-60's and I noticed a substantial difference in warm-up time. I had been up to temp in 2-3 minutes but was in the 5 minute range today.

I also noticed my max temp was in the 180 range where before it was in the 190 range. I have the foam in my trunk so I guess I'll play it day to day as to have it in or not. It's only a 2 minute difference in warmup time but it is a hit to FE.

[Daox]

Do you know if there are any xgauge codes for reading inverter temperatures? Also, is the inverter coolant circulated through a separate radiator? Dang I really need to get a service manual!

[Matt Herring]

I asked the same question over at priuschat and I was told the only way to monitor inverter temps was with Can-View. SGII cannot be programmed with XGuage to monitor inverter temps (bummer). Kind of flying blind on grill blocks...scary!

I'm not sure on the inverter coolant but I would guess it is circulated through a separate radiator as the ICE engine is able to operate at a much higher temp than the inverter and running ICE coolant through the inverter might not be at a low enough temp to cool it sufficiently. Just a guess though.

[Matt Herring]

Originally Posted by MetroMPG

OK, but nothing inherently damaging about running dry. Only if the driver continues blithely pushing onward under battery power alone.

It's surprising the standard programming in place that normally protects the NIMH battery by managing its state of charge "window" doesn't continue to protect it in a case where there's no gasoline.

So there's nothing to prevent it being fully drained if you keep driving with no fuel on board? (Doesn't it operate with something like a 40 or 60% lower limit on SOC in normal operation?)

Metro,

Topical thread on priuschat relevant what we were discussing the other day about a Prius running out of gas and having to use the battery to limp to safety. Gen I and Gen II it is possible to use the battery to do this (until it completely discharges)...But...

This involves a GenIII Prius but highlights the safety concerns with running out of gas in a Prius...the poster intentionally ran out of gas to see what happened as the Gen III has a standard tank and not the Gen I/II inflatable bladder...FYI - this guy does alot of testing with his Prius and provides alot of info over there for other posters so that's why he ran it out of gas on purpose. Pretty scary and even MORE important to not run out of gas in a Gen III.


From BWilson...
Start Quote
"Tonight I found that running out of gas in my VZW30 (2010 Prius) completely removes all traction battery power. There is no motive power to get to a 'safe place' to refill. I was able to coast to a parking lot but basicly:

* power steering failure icon - this is the only warning light, IMHO, totally inadequate
* all power indications 'off' - it is as if the car had been shifted into "N"
* shifting to "N", stays in "N" and does not return to "D"

I can buy a new traction battery and have no problem with being put in "EV" mode. But the car would not shift into "D" nor respond to "EV." Compared to the NHW20 and NHW11, this means a valuable safety feature has been lost.
End Quote

[Matt Herring]

My newspaper article on hypermiling came out today...

Drive down gas consumption by hypermiling your commute - SalemNews.com, Salem, MA

[Daox]

Good article Matt. Nice improvement on her car too!