If I read the specifications right, the temperature sensor on the IMA battery module will trigger the cut-off at 90C (194F). Since the IMA power module pumps air from the passenger cabin to the trunk this temperature limit is easy to reach when the car is left in the sun for a while.

Well, I believe this is still a highly subjective topic because it depends on our driving regime. I have to say that Tarabell's article was instrumental for me to connect all dots to my driving puzzle - of course for each of us - milleage may vary . Since I drive mostly in city traffic, I take my IMA battery state of charge very seriously. As a result I believe the following rules work well for me:

- At a stop light I try to stay in the right most lane preferably trailing some vehicles ahead of me. This will allow me accellerate gently in order to avoid using any significant amount of assist (often staying below 2000 RPM, the lower the better). It took me a while to learn how to do this one and I am still learning.
- If I happen to be stopped at a red light ahead of the pack, I will accellerate quickly while staying below 3000 RPM. I will incur a lower RPM (<3000) if I can get away with it, otherwise my goal is to briskly arrive to my top speed +7mph. This will consume IMA charge, but I try not to be wasteful by creating too much of a gap between myself and the car behind me. Then if I can take a slower right lane I will ... and then I play the pulse and gliding game while avoiding EV assists.
- I try to maximize my regen opportunities without falling victim to un-necessary drag. As many have suggested, driving with enough space in front of you (DWB) does wonders since it allows me to choose bettween a glide or a regen opportunity. It all depends on how the traffic lights change and what is possible for us to see ahead.
- Driving with load (DWL) does not work very well in most city traffic conditions (for me at least) because we are likely to have impatient drivers behind us. But if an opportunity arises then I make sure I avoid using assist (at least keep it to an absolute minimum).

Cheers;

MSantos

 

If you ever catch yourself in a situation where your mpg has dropped because you have some jerk ridding your tail and pushing you to go faster, you can always draft a semi for a few miles to repair the damage. Drafting is awesome for mpg. I'm always looking for my victim truck now on the freeway.

 

Chesleyn, the few drivers I've talked over CB with tend to take two distinct views of us drafting. One group hates it outright simply because you're in a blind spot, and that freaks them. Truckers are, by and large, some of the safest folks out there, and they worry about whether or not you'll be able to stop quickly enough. The second group doesn't mind (it helps their efficiency as well... it's why Swift has those clamshell things on the back of their rigs), so long as the person doing the drafting knows what they're doing. This means things like maintaining a safe distance (you don't need to be right on their bumper.. I've found that even being 4-5 car lengths behind can still result in a good draft, especially against a headwind), helping them drive (if you're coming up on construction area saying "all trucks left lane", for instance, you merge first, then blink your headlights to let them know it's cool to merge over as well), and just being generally cool about things. Thinking of them as "victims" certainly doesn't make us seem all that friendly, especially when they're doing us a favor.

 

msantos,

Thanks again for the additional details. Things are starting to come together in my head as to the main reasons my wife is getting 38mpg while I get 48-52 mpg. I believe the A/C setting very low was a major factor, but think most of the reason is due to management of SOC of which the A/C was a major contributor. I notice when I get in the car after she has driven it that the battery level is only 4 or 5 bars. I usually end with 7 bars. I believe she is probably using battery assist while accerating from each light, and not maximizing regen opportunities. Even if she does try to maximize regen under these conditions, it may be possible to be slowly heading negative on SOC until she gets to the forced regen level. I pumped her tire pressure up to 43lbs. yesterday to see if that helps.

I have applied most of Tarabell's techniques to my driving, which has gotten me over 50 mpg consistently and the car still only has 700 miles on it. I have not added the pulse/glide technique yet. Can you give more details on how this is done and under what conditions? I understand how to get the car to glide with no assist or charging, but do not know exactly how to do the pulse/glide together.

 

I would recommend you get it directly from the master. You can find Wayne's latest article here.

Cheers;

MSantos

 

Just wanted to throw in my experience for the record. I keep the AC on Auto at 73 degrees all the time here in Florida. On my 25 mile commute to work I've been getting anywhere between 51 to 54 MPG. The commute is about half interstate (60-70 MPH) and half city travel. I don't over-inflate the tires, they are inflated to 35 psi.

I can think of three factors that likely help me achieve this economy --
1. gentle use of the gas pedal; coast as much as possible
2. no ethanol in the gas here
3. park in a parking deck at work, out of direct sunlight

Even with the AC set at 73, the car auto-stops at each stop, even when I'm crawling through the congested streets at rush hour.

On the few occassions that I've had to park in the sun I observed the Auto AC working much harder to catch up.

-Derek

 

Msantos,

Thanks again. I read his Prius specific article, which gives a lot of insite into the technique. Can you add any HCH-II specific details on your implementation of P&G. What speed do you like to use as the top target? I live in MD and we have rolling hills with not much flat area, any suggestions for P&G on small hills?

Derek, we ceratainly have RFG with Ethanol here, which is the worst combination you can have.

 

Well, I can't consider myself an expert in this matter but here's what I do:
- I always try to pick a top target speed that exceeds posted speed limit by 7 to 10mph. I gradually climb to the speed (preferably without using ev assist) then I glide for as long as possible. I only use the P&G technique when the frequency of the pulses is small enough to guarantee long glides otherwise I drop it because it may cause more wear and tear of the vehicle than it is worth.


MSantos

 

Why is P&G more wear and tear on the car?

On the freeway during long trips I Pulse and semi Glide. Normally I get the car up to about 68mph then slowly under throttle let it dwindle to 63mph(keeping the car in the 100mpg to 50mpg meter range. What I do is not an official glide because the gas engine is engaged.

The official P&G I only use during my daily stop and go traffic, and sometimes around town with traffic lights. It really helps to maintain whatever MPG I gained while driving on the highway. Sometimes I can actually start to gain quickly if everthing lines up right.

 

That is a good question.

I believe this topic has been debated alot already in this and other forums. But the general consensus is that it is less stressful for an typical ICE to operate at a lower steady rate than it is for force it to operate over a varying RPM range. While there are circumstances and operating variables that dimish the negative impact of a varying RPM regime, it appears that in the end this belief is generally valid for most civilian ICE applications.

With regards to P&G: That is why I prefer to keep my pulse frequency low.

Also note that I am not claiming to be an expert at P&G. I also cannot say much about freeway or highway driving. Unlike most folks with better skills (& better posted FE #'s) I drive solely in city traffic.


Cheers;

MSantos