Thanks for the responses.

Bob, is that part number for the block heater from the Toyota dealer, or another company?

 

The block heater part number is from Toyota of Canada. It has not been available from USA dealers. What folks have done is find 'a friend' in Canada and bought through them. Last year, I saw a group buy organized in PriusChat.com.

I think "Tidewater" is from Canada. You might PM him to see if he'd like to be the broker. Alternatively, he might find someone in the local Toyota parts department who would sell them. Really, this is one of those cases where if I were interested, I'd get a bulk buy together and then offer them via Ebay priced to pay for mine. That would make everyone happy.

Lessons learned, don't go with a JC Whitney water heater. I bought one and it sits in my trunk as a reminder. The JC Whitney transaxle heater has worked out OK and was fairly reasonable:
http://hiwaay.net/~bzwilson/prius/pri_WS_020.jpg


Bob Wilson

 

Both block heaters; US 00113-00213-00889 and Canada CO140-00889 are the same heater from the same company, Pyroil of Canada. It comes in a box labeled Toyota and the Canadian part number, even if you order it from a US dealer. It is a official Toyota part produced by a third party, hence the US 00113 prefix. All US dealers can order it, although I've heard that in the Souteast and Gulf regions many do not have access. Many dealers do not want to bother with the third party parts so they will tell you it is not a Toyota part. It is. MSRP $39, many charge more.

Wayne

 

Thanks for the info

 

Speaking to the original question: I use both approaches depending on my starting point. My fiancee's 400' driveway starts level and gradually transitions into a slight downhill toward the road. I begin moving slowly right away. When gravity will carry it downhill I shift into N until I approach the road. Using the block heater, that's generally enough time to allow it to get out of S1.

My landlady's driveway is a different story. It's a quarter mile, largely uphill, with a particularly steep climb at the beginning. If I begin driving immediately, it really draws the battery down, and that costs me opportunities to drive in stealth mode a short time later. So when I'm there I sit until the ICE shuts down. Again, not long, maybe 30 seconds, with the EBH.

 

Interesting. I think that is what I've learned from the responses in this thread.

Basically, if you have a relatively low load drive at the beginning, go ahead and drive. If you have some hills, or need to get up and go fairly quickly [main roads etc], then you might be better off waiting until the ICE shuts down.

I did some experimenting with this the last two days. Where I would normally sit and let the ICE do it's thing, I started driving immediately. This has resulted in slightly better numbers, but it's difficult to say if the overall trip had different variables that contributed to the 1-2mpg difference.

 

Yeah, the whole question strikes me as confusing mpg with total fuel used. People focused on their mpg number don't like driving anywhere at 25 mpg when they could be driving there at 50. When the car is parked, you're getting 0 mpg, but you don't have to "count" it because you're not accumulating any miles, either. But it *does* count in terms of total fuel consumption. Just getting in and going is ultimately going to use less fuel, even if it hurts the almighty mpg number for a few minutes.

--doug

 

From my understanding (and very limited scan gauge testing), the 2004-2007 Prius drives mostly on battery while warming up (as long as you don't accelerate too much). During that time, the engine warms up and also charges the battery.
So, it seems counterproductive to put the car into N, since then you're burning gas without charging the battery, which is a total waste (even if the fuel consumption in N is in fact lower).
Also, in winter, the more time you spend in your car (with heat on), the more heat the car has to produce, so letting it warm up first also seems like a waste. My current thought on this issue is just to drive it, preferably slowly but without stopping (but I could be convinced to change my mind). Has anyone with a 2004-2007 Prius done this testing like Bob did for his 2003 Prius? Or can we be sure his tests apply to the newer Prius?

 

Hi,

You might find this chart interesting:

What we find is during "P" or "D" warm-up, the ICE is 'loaded' with some power generation. But the fuel burn is pretty intense. However, if you slip the 2001-03 into "N", you can cut the fuel burn significantly. The block heaters simply shorten the warm-up interval.

I'm repeating the warm-up test today and tomorrow to once again, verify what we are seeing. However, Ken@Japan suggested the use of "N" results in a longer warm-up interval at the lower rate and winds up be a wash with warm-up in "D."

If you haven't guessed, my current experiments are looking at improving the warm-up cycle. With luck, the results will show up this winter with much improved, cold-weather performance. But some of the preliminary data suggests block and pan heaters work year round.

Bob Wilson

 

OK, so:
1) if the fuel burned is higher in P or D (than in N) , the question is: Does the battery charging during warmup in P or D make up for the extra fuel burned ? Perhaps not, since energy conversion is inherently inefficient.
2) if the total fuel burned is the same (according to ken japan), then P or D would be better, since it also charges up the battery.

Also, how is this different in winter vs. summer ?