EV mode at every stop

EV, ECO, POWER MODES.... First I am technically naive so don't laugh to hard. I am observing the following:

EV can give me a great few miles and find it useful is slow congested traffic. My issue is once the EV mode depletes the battery I am in ECO mode and seem to be in constant gas consumption (based on the idiot meter on the dash).

Someone tell me: if I am able to leave vehicle in ECO mode and hit the sweet spot where the meter is at top of its recording range, am I not getting as good as or better mileage going this route instead of EV Mode?

Also....how can I find out how much charge my battery is getting? I have more times than not when Prius says EV isn't available. (putting it into play from a standstill and exceptional slow start)?

 

It's all about balancing how much power you use in EV Mode vs. how much energy you can regenerate with braking. The Energy in the HV battery is best thought of as a bank account or an American Express card. With an American Express card you must pay the balance of the loan in full each month or else you are penalized!

The HV battery energy is not free. The energy came from gasoline and regenerative braking. Because there are losses associated with converting gasoline energy into electrical energy you should avoid doing this at all costs. Energy gained from Regenerative braking is somewhat free and better than gasoline energy BUT not if it was gained at the expense of gliding distance. In most situations we will have to apply the brakes when coming to a stop and that is your chance to regain some energy for the HV battery. If you are driving correctly you will not be able to capture much energy so therefore depleting the HV battery by using EV mode at every stop is not very efficient. You will end up requiring the gasoline engine to recharge the battery and that is not efficient due to the conversion losses mentioned above. Do you see where this is going?

Thus, the most efficient method of accelerating that I can identify is to use a little bit of EV power just to get you rolling because the ICE at this stage of acceleration is simply too inefficient. Once past about 15mph or so then fire up the ICE to continue accelerating. The ICE is now becoming more efficient than the HV battery due to conversion losses and you should still be able to regain the energy lost during this acceleration stage by your next stop or two.

You can use the Torque App on a smart phone or purchase a Scangauge II to monitor SOC % numbers more accurately.

 

I understand and thus see really no use for EV if the gas engine has to kick in once EV has been exhausted because it seems like more gas is being consumed right after EV mode, rather than seeking the "sweet spot"quickly/aka "pulse-glide".

PLEASE TELL ME: What the heck is ICE? How does that translate into driving technique?

 

I agree with you that using EV up to 25 isn't the most efficient means of taking off from stop.

ICE stands for Internal Combustion Engine

 

Pulse and glide is the mode efficient way to drive but that doesn't come into play until after you have achieved a desired speed. I.E. you still have to accelerate from a full stop at some point. The method we are discussing is how to move forward after a full stop.

ICE = Internal Combustion Engine.

To make this very simple:

1. Put the car in EV Mode
2. Accelerate moderately up to 15-18mph or so.
3. Take the car out of EV Mode by pushing the EV Mode button again (don't lift off the gas while changing modes).
4. Continue to accelerate using normal engine/ev power up to your desired speed. Make sure the HSI indicator is no more than 3/4 of the way through the ECO section. If you enter the Power section you have gone to far.
5. Once you reach your desired speed, lift off the gas pedal completely then reapply just enough pressure to maintain your desired speed.
6. Anticipate your next stop and try to estimate how far in advance you can glide to the light if you were to lift off the throttle. When you are ready to glide simply lift off the throttle completely then reapply a tiny bit of pressure so the HSI indicate shows neither regenerative braking or EV/Eco. If you have trouble doing this then a little bit of HSI indicator showing in the EV section is ok but not ideal.
7. Now glide to the next stop. If you have to apply the brakes to stop because you are going to fat then apply the brakes gradually soas to maximize regen braking. Remember this and next time you are in this area lift of the throttle and enter a glide sooner so you wont have to brake so much!

 

AH FINALLY!

So, I am basically doing the steps you state, I am just not manually popping buttons between EV, ECO and POWERUP......... I can give it a try to see if I have enough mpg gain to make it worth using this way. I guess you could say I am using the ECON mode as the "automatic" instead of manual transmission. I also just try to listen to (what I hope is silence and alter driving with rapid acceleration to induce silence aka/glide mode)

Just how much improvement in efficiency/mileage are you getting with this process?

 

If you can do this without using the EV Mode button then I would continue to do that. I have a feeling that using the button wastes more energy due to more rapid acceleration then if you just babied the pedal more.

I'm not sure of the difference because we are still testing this out. Wayne Gerdes recommends it and he is THE expert. In theory it should help quite a bit when coupled with other hypermiling techniques.

 

Thanks! I must be doing ok with it. My husband doesn't give a rats behind about getting the best mileage, if he wants to drive like a bat out of hell then he pushing my meter down to 39 mpg. (he likes to go 80+.........don't get me going on that one) I'll try to keep him out of my car while I do a few trial runs of my driving technique and do a full fuel up to get some actuals.

 

LOL that sucks.

Well, if you end up having your full tank average screwed up because of him then you are free to keep resetting the trip meters while you are testing. Maybe you can come out with some solid data for us? Most of us are too fixed on getting a good full tank to reset the trip meters. lol

 

Ah we have the best "ying yang" relationship ever!

I'll look like a goof at the gas station stopping for 2 gallons of gas to do my math! I don't trust the metered estimates and need to work from full tank to full tank.

 

Roughly speaking, the meter is biased but consistent, while gas pumps are unbiased but inconsistent. If you are looking to optimize your driving style, you are better off using just the meter, and comparing it to itself. If you are interested in comparing with others, use an average of fill-ups. Also, the Prius gas gauge doesn't notice fills of less than about 3 gallons, so small fills will confuse things even more.

 

For short refills such as 2 gallons, the meter will be more consistent than the pump results. Consistently high, but still reasonably consistent. So reset one of the Trip meters each day when you start driving, and use that for score or driver feedback until hubby's next drive. Then reset it again.

 

To those that say more energy is used by accelerating faster up to 15 mph in EV Mode versus accelerating slower, think of it this way, at twice the acceleration rate you consume the battery energy twice as fast, but for only half the amount of time, so the total energy used should be approximately the same. I guess the next question is what is the most efficient acceleration rate up to 15 mph in the EV mode?

BTW: The above technique is what I've been doing for quite a while now based on Wayne's 15 mph value. But I accelerate as fast as EV mode will allow up to 15 mph which is a rather satisfying acceleration rate (close to average acceleration of traffic). Accelerating not using the EV Mode and keeping in the EV region is not feasible for most drivers in most suburban commute situations.

 

Well folks.........I'm still driving the tank of gas from earlier this week and have managed to keep hubby out of the car so I can get some real test numbers. Going purely by the screen mpg I am at 48.8. However, I must say, I left on my trip this a.m. with screen mpg reading 45 (I used remote AC twice yesterday in 100 degree weather) The trip involves 65 mph driving, but also three 30-45 mph regions with lots of lights and lots of hills. At every opportunity to choose between glide to stop and brake to stop, I opted to use mostly braking to recharge the battery. (I seem to run it depleted alot for some reason) Anyway, that problem was solved. I also used EV at every stop and allowed car to naturally go with traffic and sometimes "tip" from EV to ECO mode at the rapid 15 mph, and then the slower longer distance of 25 mph. EVERYTIME I did this I had an increase in mileage recorded 0.1- 0.3.

I've been so excited to try the EV option and breaking and am pleasantly surprised that it doesn't make my driving appear unsafe; abnormal amount of attention needed, etc.

It's only one trip and one trial, but I'm a firm believer in correctly using EV and brakes. Fuel gauge shows 1/2 full; trip odometer reads 200+ miles (very rough number sorry)

Now to eliminate the energy consumption behavior with remote AC, sitting in car with AC on, over excelerating going up and down hills more than necessary......... (all that naughty stuff you hyper milers probably wanna kill me for!) lol

Have a good evening!

 

LOL! Good for you, etobia.

FWIW, I used the EV Mode at most stops during my last trip (49miles from 168ft. ASL to 50ft. ASL) and ended at 76mpg. That was a mixture of rural roads at 50mph and a little pulse and glide session along a levee road. That trip really helped bumped my mpg from 63.3mpg to 65.1mpg (approx).

So relaxing!

 

What was your method and do you think you will continue to try it?

 

I was just screwing around using the EV Mode button and accelerating to either 25mph or 15mph. It seems, on a flat road that it costs about 1-1.5% SOC to go from 0mph to 15mph and about 3-4% SOC to go from 0mph to 25mph. It's hard to recover 4% SOC when gliding properly.

I also tried to set the cruise at 37mph and let SOC drain until the ICE started up to recharge the battery. This was a bad idea compared to pulse and glide. I wasted half my time on the levee road with that method and I didn't even gain 1/10th of a mpg! Pulse and glide was much better! I was missing somewhere around 10iMPG with the ICE charging the HV battery compared to the same mph with a full SOC.

My pulse and glide method:
Accelerate up to 41mph while keeping iMPG at around 30mpg.
Lift off throttle and enter glide
Glide until I reach 25-26mph then accelerate back to 41mph.

While this is not realistic for most situations, it is easy to find a lonely stretch of road to perform this technique. It helps make up for any issue that screwed up your mpg earlier in your current tank.

 

Just curious, what is your thinking for stopping your acceleration at 41 instead of 45? Less wind resistance?

 

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There was no real pressing reason other than I sometimes have a hard time entering a true 0RPM glide until below 42mph. I need to do more testing on this, however.

I've looked through early reviews on the GenIII by the guys at CleanMPG.com and I think that maybe I was babying the throttle in the pulse portion of the drive. Dan believes the sweet spot for RPM is 1600-1700rpm which on a flat smooth surface would put you in that 3/4 HSI section we always talk about. Instead, I was trying to pulse at 30iMPG which put me somewhere between 1/4 and 1/2 HSI. Maybe I should try accelerating a little faster next time. Wayne found that keeping RPM lower yield better results for him but keep in mind these were time limited test sessions. Since I normally do not pulse and glide I have not researched this enough. I'd be happy to hear your thoughts. Pulse and Gliding is a PITA so I hate to do it unless I know I can pull of fantastic results. lol Maybe ksstathead can help clear this up a bit?

Here are some relevant threads. You have to read quite a bit to tease out the information.

CleanMPG Previews the 2010 Toyota Prius-III - CleanMPG Forums
2010 Prius-III P&G, SHM and WS FE techniques rehashed, defined and refined - CleanMPG Forums