EV miles can be regenerated by PIP after EV depletion

It is my understanding that the energy regenerated downhill while or during regenerative braking in EV, will be kind of "locked away" for later use, for example city driving. When you do this in HV, it will essentially be used up in order to maximalize fuel consumption in this mode. During climbing, the HV mode strives at keeping the SOC (state of charge) of the battery stable, and this costs some gas.

In Paradoxes thread, it was not clear to me whether the whole is more economic or not. I understood he just found it fine to dispose of extra battery charge when it is particularly pleasant to drive in EV mode. I may be wrong. Maybe you can put your question in his thread?

Jan

 

As I understand it, when you do regeneration, the energy goes into the battery the same way regardless of theEV/HV setting. But when you start to need power, then the EV/HV setting comes into play. If you are in EV mode, then the battery will be drained. If you are in HV mode, the gasoline engine will be used to maintain the SOC that it had when you hit the HV button.

 

The way I do is different. I cite from Paradoxes thread:

I think he got it right.

Jan

 

I think we are saying the same thing. You go up hills in HV mode so the gasoline is burned to preserve the current battery charge. When you go downhill, it doesn't matter which setting you have, and your EV range goes up, as regeneration charges the battery. But some time before you get to a situation where were you need power, you hit HV to establish a new, higher, state of charge point. You will then burn gasoline to preserve that charge level, in HV mode. You can build up the charge in the battery using this "stacking" technique by going up and down hills.

But my fundamental point still stands: what have you accomplished, other that getting a high "EV miles" statistic. You have just used the gasoline engine to charge the battery, rather than charging the battery from the plug. But you have burned the same amount of gasoline and just shuffled the energy around a bit.

 

I think the basic idea is, you have the option to decide when you want to use HV or EV and by utilizing this method to "stack" EV mileage, you can end up with a fair amount of charge you can choose to use when you want to use it.

Many here have examples of when doing so may not be as efficient. Sure, going up a hill in HV and then storing the energy as I go down hill is just trying to recapture some of the energy used going up the hill while burning gas. But again, this is just a method that enables the driver to decide when to use gas and by doing so, possibly save up, bank, or stack enough EV range as to make it useful for some future driving where EV would be more beneficial.

Here's an example:

Let's say I drive 10 miles before I reach a big hill. When I reach that hill, I can leave it in EV and exhaust my remaining charge. However, I choose to switch to HV, retaining, say 1 mile of EV range. I climb the hill. On the way down, I regen another 1 miles of EV, I hit the switch to EV, then switch it back to HV. Now my stacked/banked EV range is 2 miles. I reach a second hill, climb that in HV, regen another 1 mile coming down. By now I've stacked 3 miles of EV (2 from the first hill and added 1 more after the 2nd hill).

At bottom of the hill, I drive 1 more mile in EV to the city where I plan to run some errands.. maybe grab lunch (1 hour).. I now have 2 EV miles left.. stop by Home Depot/Costco/Target/Walmart which is 1 mile from the restaurant (1 hour there).. then pick up some dry cleaning 1 mile away from store..

Now, had I left it in EV from the very beginning, I would've consumed all my EV range going up the first hill.. consumed whatever I regenerated from the 1st hill going up the 2nd hill.. and then consumed whatever I generated going down the 2nd hill as soon as I reached the city. That would mean my trip from the restaurant to the store and the trip from store to dry cleaner would both start the ICE (cold start since there was an hour in between each trip) for a 1 mile trip

This is really no different than those of us who decide to use the ICE on the freeway and save the EV range for city driving. The only added dimension is that there is a way to build up/stack your EV range for parts of your drive that would be better suited (more efficient) for EV.

Its a choice any PiP owner can make. Don't want to be bothered by it? Then don't.. just drive it.

 

Edit: Paradox made his point in the mean time...

Hi Charles,

I am not sure and rather think we highlight different aspects. Let me try and summarize.

In HV, when driving downhill and/or braking, the EV range climbs. While continuing in this mode, the EV range drops again, meaning the regenerated energy had been consumed. It is not said how much fuel this helped saving, probably some indeed.

In EV, a similar increase in the avalable EV range is obtained. While continuing in HV mode, the EV range remains steady. The HSD system working as usual, the SOC stays largely stable.

Repeating the above in EV several times, it is possible to "collect" an almost full load of battery power, which can be used for EV driving when it appears "nicest".

Paradox considers this as a substantiel gain in comfort. That would be the accomplishment you were looking for. He did not say it was good or bad for fuel consumption.

That is what I wanted to bring to the attention of the followers of this thread.

It surely requests a proactive driving style, which may not be liked by everybody.

 

So, Paradox, the point of stacking for you isn't gas economy or anything like that. It's that you really enjoy driving in EV mode and stacking is a way to increase the number of miles you can drive in that mode, which makes perfect sense to me.

I was just worrying that some people might think that were somehow getting more EV miles from the plug or using less gasoline using this technique, which I don't think is the case. (OK, there is case where the ICE starts just to warm itself up, but how much gasoline is that?)

 

I depleted my EV battery completely on the way home from the office yesterday. I also threw out my back and was in pain and just hobbled into the house last night not caring to plug in ... and when I started the car this morning, I had .08 EV miles back. That happens to me from time to time... but usually .06-.07 so maybe it's getting better over time!

 

It's quite nice being able to have your cake and eat it too!

I'm very pleased with how efficient the system is even without plugging in.

 

I recently got 69 mpg doing 65 mph in HV and was quite pleased with that #. Total trip about 120 miles. I did bank some EV charge to use later back in suburbia.

 

Sorry to hear about your back Dianne, I am going thru the something right now and am seeing a physical therapist, it can be really debilitating! Almost all healthy batteries will recover a small amout automatically, within PIP we have extra charging bonuses. As John described, I generally leave a EV supply on a trip where I think I will use up the EV anyway.

 

Starting from Big Bear (San Bernardino, California Mountains) with a full charge, I can get all the way through Mentone and still have a full charge. And plenty of charge left at the hwy 38 entrance onto I-10. The drive is mostly downhill from 7K ft., but has ups and downs. Always enough battery to makes the uphills, and the PIP charges fast on a downhill.

 

Question, if the ICE kick in to burn off electricity. Does it suck any gas?

LT26i ? 2

 

no.

 

Actually it can burn gas in this situation if it is not warmed up yet. when I leave my house with a fully charged battery and go down a steep hill the ice kicks in to "burn off extra energy" or whatever. Then I stop at a stoplight at the bottom of the hill and the ice keeps running for a minute while the soc is still at 85. (full charge).

 

Once a cold ICE starts, it has to fully warm up to meet emission specs. But, is it really starting when used as a brake? I would think "started" means the first time fuel is suppled to the engine. My understanding is that fuel is not supplied to the engine when used as a brake.

 

Yes, it really is started. The ICE will run until its warmed up as you pointed out.

This happened to me a few times in the first few weeks of ownership. I then started putting it in N as I was coasting down the hill where the ICE would normally start and that prevented the excess regen. But I've since switched to braking later and harder to prevent the excess regen and havent had the "problem" for a few months now. However, it happened again last week (asleep at the wheel, I guess).

Aside from the ICE running until its warmed up, you'll also notice your trip MPG drop (I reset it each morning). And it drops a lot.. its painful to watch (I'm only about 0.5 mile into my trip to work.. so it goes from 999 to something in the 100s until the ICE shuts off).

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Here's a log of my morning commute from 3/20/2012. Although I didnt log anything to do with MPG or the fuel injection system, you can see that the Engine RPM starts at row 132. It "idles" at around 1500 RPM for about 1 min 17 seconds where it drops to 1300 RPM. It then runs for another 3 minutes and 44 seconds before it shuts off. You'll also notice that the "magic number" is about 84% SOC where the ICE will start to prevent excess regen.

Dropbox - torque_phv_20120320am.xls - Simplify your life

 

I do enjoy your phraseology.