Hybrid Battery Consumption Question.

[barrycoll]

"Holding the car with the parking brake instead of P, saves an immeasurable amount of energy."

is that parking brake AND P, or parking brake and N, or parking brake and D....please greenjuice???

sorry for being dim, but time eventually erodes ones personal SOC to below a 40% level

[GreenJuice]

Sorry, my fault for being obtuse (I'm running low on SOC too after today's commute in London through strike action!).

Firstly, I should have said 'unmeasurably low' not 'immeasurably' (that what you get for trying to type on glass).

So remember this comment was in relation to the 'Japanese Dance' (we seem to have coined a new phrase!):

Once you have come to a halt, and already in Neutral as in this dance, you have a number of option to hold the car there:

a. Parking brake alone (and remaining in N)

b. Parking brake and shift gear to P

c. Gear in P alone

d. Parking brake and shift to D (not advisable as the car will try to 'creep')

The one that consumes the least energy is (a). I was trying to make the point that the difference between (a) and ©, or (b) for that matter, must be very minimal, but for these extremists considered 'not zero'.

I feel that shifting to P is somewhat similar to the 'olden days' method of leaving the car in gear when parked. So on a personal note, I would not do this when in stop-start traffic. The chances of being shunted from behind and destroying the gearbox must be infinitesimally small and should not be exaggerated. However, the consequence of it happening are great - apart from the cost and time for repair, you might not even be able to drive from the scene (although I would be happy to be corrected on the latter).

Hope that clears thing up a bit. Let me know if you'd like me to post some experiments with ScanGauge to help with understanding these cars.

If there are any interested in hypermiling, be aware this kind of driving can be very challenging and addictive!

For Toyota Hybrids, basic things to be aware of and look up are:

1. Five stages of Hybrid operation (engine warm-up)

2. Pulse and Glide

3. Warp Stealth

4. Superhighway Mode

[GreenJuice]

Whoops, this sentence came out all wrong - this posting software is just too clever!

The following should have read, '.... the difference between ( a ) and ( c ), or ( b ) for that matter, must be very minimal....'

.... that the difference between (a) and ©, or ( B) for that matter, must be very minimal, but.... .

[Joseph D]

One metric missing that I'd interested in is the current draw whilst sitting on the footbrake with the creep off. I am picking that it would be not detectable or else certainly less than the 500 mA draw of the dipped headlights.

Not sure I quite understand your comment, so forgive me if this response is wrong.

The lowest level of current draw is 1.4 A. If you are stationary in Drive with the foot on the brake, this is what you see on the XGauge BTA.

If you go to Neutral or Park, it remains the same.

If you stay in Drive and lift your foot off, the car will creep and BTA rises to 4.9 A (it soon settles down at 3 mph to a higher or lower value depending on the road incline).

If you then brake again and come to a halt. The creep is switched off in a fraction of a second and BTA drops to 1.4 A again as soon as you are stationary (not before).

If you remain stationary and turn on the lights (or allow them to come on in the 'auto' setting) the reading on BTA is 1.9 A.

Yes, thanks that answers my question.

Apart from the obvious damage caused by shunt in the rear, why do they do the 'dance' rather than what I do?

The 'Dance' was for the Gen2 which did not 'switch-off' the creep as easily as in the Gen3.

Hypermilers trying to sqeeze every ounce of energy developed this method, but it could easily be argued that the added value is minimal!

Remember that one of their aims is also to minimise *all* energy conversions, both in and out of the traction Battery (as all conversions are theorectically wasteful!)

Basically, as your speed drops below 6-7 mph, you do not regenerate any more energy from deceleration and friction braking then takes over. At this point, you might as well 'electrically disconnect' MG1/MG2 by going into Neutral to minimise the chance of energy conversion. Keeping your foot off the foot brake has a further minor energy saving which is that your brake lights are off and brief brake pump action is avoided (I am not justifying this, just explaining!). Holding the car with the parking brake instead of P, saves an immeasurable amount of energy.

One other point to make is that hypermiler's actually prefer to not stop if at all possible. Therefore, they would aim to 'Glide' (I'm using this word in the specific hypermiler language; i.e., 'assisted' with foot on the accelerator keeping BTA at 1.4 A) towards the 'potential' stop situation but actually hoping they don't actually stop, flicking to Drive and taking off on their next 'Pulse' phase of a P&G cycle.

Hope that makes sense!

Thanks for that explanation, it makes sense and I take your point about hypermilers.

Personally, I don't have any problem stopping the creep in my Gen II, you just have to be aware that you need to press a little more than what you need to just hold the car stationary. As I usually have the Energy display showing on my MFD, I can visually see it too, but I have driven a Gen II for so long it is now second nature.

[barrycoll]

after a good nights sleep, all is now clear, but it is fascinating how the loss (or addition) of an important modifying word, can change the context 180 degrees

it is no wonder that Far Eastern Instruction books are so fascinating

could you be persuaded dear Greenjuice, to write a paragraph or two, on your personal take of those Four Topics of a successful High Miler?

...most forum members would be very interested, and most dont have a Scanguage....

[GreenJuice]

could you be persuaded dear Greenjuice, to write a paragraph or two, on your personal take of those Four Topics of a successful High Miler?

...most forum members would be very interested, and most dont have a Scanguage....

I’m hardly a successful hypermiler! Just someone who developed an interest and got a bit addicted to some of the ideas!

Apologies for the late response - really busy at work at the moment. I will post this as a new topic, but want to just to note here that the 4 topics above actually relate to aspects of hypermiling which are specific to the Toyota Hybrid/Prius. Hypermiling can of course be done in any vehicle. These four are the ones which may need to be taken into account when driving a Toyota Hybrid.

[timberwolf]

Your Hypermiling post looks pretty good. I don't want to pollute your post with my nonsense, so I'll post my comment here.

If you can believe the article, this man made his wife walk to/from the shops whilst he drove to save a calculated 10p in petrol: http://www.mirror.co.uk/money/personal-finance/money-saving-tips-from-the-man-so-miserly-he-stopped-353500

[Grumpy Cabbie]

lol 10p here and there and then the inevitable £thousands in a divorce settlement. At least that's the way it's heading. Mrs Cabbie would have things to say if I made her walk whilst I drove!?!