Jimmy,

We all owe you a big thanks for this driving tip.

BRILLIANT !

Some related thoughts:

1. The A/C is, of course, electric in the TCH; so, the way it affects mpg is by draining the battery so that the ICE needs to turn on more to keep up with it.

2. I suppose that a speed in the range of 45 mph or so probably keeps the ICE at or near it's most efficient RPM.

3. I also have definitely observed that the lower the SOC, the less the car will run in EV, Fuel cut, or possibly even Heretical modes.

4. One of the ways that the use of auxiliary batteries help boost mpg in this car is by maximizing the time that that the TCH SOC stays quite high, thereby maximizing the time that EV, Fuel cut or Heretical modes can be maintained.

 

Jack, your hit the nail on the head with your 4 above thoughts.

My wife started driving to town at 48 mph 11 years ago when we first moved out here. She got really good mpg numbers out of her 4-cyl dodge shadow.

I had read in a Popular Mechanics magazine back in the 60's, that the engine is most efficient at 48 mph. This was in a article of improving gas mileage with the carburated V8's of the time.

Lots of efficiency improvements with toyota engines from 1999 on up. Using a much improved computer (ECU) to help time the injectors and ignition can bring the HP up to that of a V6. Improved fuel injection, coil over plug ignition (no spark-plug wires) with the ability of the ECU to retard a single cylinder if the knock sensor senses a knock. Off-set crankshaft improves the engines efficiency. Variable valve timing, (VVT) works best to time the valves to your driving speed. (RPM)

All aluminum engine with cylinder sleeves that puts the coolant closer to the cylinder and pistons to better cool them. This allowed tighter clearances which helps improve the efficiency. The aluminum block helps heat up quicker with more uniform heat throughout the engine.

I feel the inline 4-cyl (I) engine is more efficient than a V6. It's main bearings are usually larger which would mean less friction.

I found by slowing to 45 mph with the hybrid, the engine seems to have less internal friction. The winds and wind hitting the front of the car is not near as bad when driving at that speed.

When on a long trip I found driving at 60 mph works best for the TCH. I up the speed to 65 and 70 the listen to the wind noise from the windshield and mirrors. My thinking is that extra 5 or 10 mph is costly on gas mileage.

I usually get 47.5/ 48 mpg when driving 60 on a two way run on the same highway.

Forgot to mention about the Atkinson cycle engine we drive in our hybrids. It works best around 30/35 to 60 mph. It don't have much go below 30 mph but depends on help from the EV. Still plenty powerful when you need it.

When the traction battery, if fully charged, the EV can propel the car up to 25 to 30 speed then the engine will kick in. Like you said, Jack, the extra Enginer system (battery pack) helps keep the traction battery fully charged for many miles of driving.

 

First thing yesterday morning I made a 4 mile round trip to the Post Office.
It's also a trip I do frequently. Conditions and traffic on this trip are a lot more favorable to high mpg than are those for the trip to church, but the best I usually did -prior to the plug-in unit was about 40 mpg.

Yesterday I clocked 80.0 mpg for the round trip.

Jack

 

I was reading on the enginer web page where this plug-in unit can run for 20 full EV or 40 blended miles. I like their idea of using the more efficient lithium batteries.

 

a few notes on this:

1. They actually say "up to" 20 EV or 40 "blended" miles. Read the "up to" literally

2. The full EV mode applies only to the Prius, not at all to the Camry, and even the "blended range of 40 miles is based on Prius experience. The numbers for the Camry are still developing. As far as I know, that would be only my own experience at this point.

3. My experience so far seems to be that there is variation in both the mpg benefit and the range over which you can get it - with the greatest benefits holding for shorter ranges and lesser benefits holding for the longest range. Makes sense to me that this would be so. The more you're using the system, the less range it would hold up for and vice-versa.

4. I have very definitely seen range up to 40 miles - coupled with about 25% boost in mpg -even with A/C

5. On the other hand, I have seen range of approx. 32 miles coupled with roughly 100% boost in mpg (without A/C)

6. A/C plays a role. While the use of A/C does not seem to have a big effect on the range at high speeds, At slower speeds in stop-and-go driving, the use of A/C will also significantly cut the range - possibly even in half.

 

A few weeks ago, I posted the following

A week later I posted that I had done 57.0 mpg for the same trip, again with the a/C and again with the auxiliary batteries in use.

Today I did the trip without the auxiliary batteries in use, but otherwise in similar conditions and with A/C in similarly hot temperatures. The result was 25.1 mpg.

 

That easily proves the extra batteries can carry the AC, but the car as well and for many miles. It's amazing how much the pack helps.

 

Jack,

I just found the Enginer Web page. I'm assuming you bought the kit directly from them, or did you have Houston Electric Cars install it?

http://www.enginer.us/

Intersting to note that the self-install 4KW kit is only $2500. Hmmmm...

Thanks,
Joe

 

You got it. And see my PM to you. Sorry I was slow on the reply.

Yes I got it directly and installed it myself.

Jack

 

In recent days I have taken the opportunity to repeat this Post Office) trip but without using the Enginer system's auxiliary batteries - both with and without A/C.

Results: 39 mpg without the Enginer system with no A/C
26 mpg without the Enginer system with the A/C

Compare to 80 mpg with the Enginer system

(As previously noted, with use of Enginer system the A/C has little effect on mpg - provided, that is, that there is sufficient charge remaining.)