How much energy does a power off/on cycle use up?

[TaylorSFGuy]

On occassion, I have to stop for a short time - bank deposit or something that requires me to power down the car and soon after power it back up. Maybe those of you with the detailed SOC can tell me how much energy this cycle uses up? I can pull in showing 3 bars used and when I power back up, the 4th bar (which was clearly partially used) is gone. Thanks

 

[garygid]

Power Down/Up uses essentially no extra energy.

What you observe is an indication that the Bar being used is less than half full. A Bar being emptied (as when driving) stays "On" until it is empty. However, a Bar being "filled" (as when charging OR when powering the LEAF On) does NOT turn On until it is at least half full.

This is what occasionally (about half the tine) causes a Bar to "vanish" when you power Off and On again.

 

[keydiver]

Good question, I have wondered the same thing. But, unlike my Prius, which has to go through the stupid ICE warmup cycle everytime you restart it, you haven't lost much with restarting a Leaf. When I drive the Prius, and stop for a minute at the Post Office, UPS, etc, I often don't shut down, just to avoid the ICE warmup cycle, but so far I have been shutting off the Leaf almost everytime I stop somewhere, and haven't seen any change in the GOM.

 

[thankyouOB]

Power Down/Up uses essentially no extra energy.

What you observe is an indication that the Bar being used is less than half full. A Bar being emptied (as when driving) stays "On" until it is empty. However, a Bar being "filled" (as when charging OR when powering the LEAF On) does NOT turn On until it is at least half full.

This is what occasionally (about half the tine) causes a Bar to "vanish" when you power Off and On again.

how superb that you, gary, are able to give us such detailed answers on these issues.
Happy New Year to you, and all.

 

[TonyWilliams]

I have been shutting off the Leaf almost everytime I stop somewhere, and haven't seen any change in the GOM.

Even if the GOM had a change, that doesn't change the amount of battery energy remaining.

 

[DaveinOlyWA]

i have seen GOM bars ADDED on power up. its kinda like a balancing teeter totter. the new bar usually disappears after less than a minute

 

[bradleygibson]

+1

Thank you, Gary!

Power Down/Up uses essentially no extra energy.

What you observe is an indication that the Bar being used is less than half full. A Bar being emptied (as when driving) stays "On" until it is empty. However, a Bar being "filled" (as when charging OR when powering the LEAF On) does NOT turn On until it is at least half full.

This is what occasionally (about half the tine) causes a Bar to "vanish" when you power Off and On again.

how superb that you, gary, are able to give us such detailed answers on these issues.
Happy New Year to you, and all.

 

[TaylorSFGuy]

You seem to be missing the point here - my concern is not with the number of bars "used". I'm wondering how much battery is being used during the power cycle. Thanks. My guess is about 1/3 kw.

 

[DaveinOlyWA]

You seem to be missing the point here - my concern is not with the number of bars "used". I'm wondering how much battery is being used during the power cycle. Thanks. My guess is about 1/3 kw.

300+ watts?? how did we come up with this?

and i guess it would be easy enough to test. 62 power cycles (only 52 in winter) should just about deplete a fully charged battery

 

[TaylorSFGuy]

You seem to be missing the point here - my concern is not with the number of bars "used". I'm wondering how much battery is being used during the power cycle. Thanks. My guess is about 1/3 kw.

300+ watts?? how did we come up with this?

and i guess it would be easy enough to test. 62 power cycles (only 52 in winter) should just about deplete a fully charged battery

It is only a guess and it keeps the post on topic. I was asking someone with a detailed SOC meter to tell us how much a power cycle uses. I would prefer not to go through a test such as you propose. 300 watts is about 2 miles for me so I know what I'm losing. If I'm told it is closer to 1kw then I know it is a much larger reduction in range. The usage of watts tells all of us how much energy will be used by the power cycle and then we can each interpret what that means to us depending on the situation - winter/summer, etc. Simple question, and I wasn't asking a thing about the change in number of bars.

 

[klapauzius]

You seem to be missing the point here - my concern is not with the number of bars "used". I'm wondering how much battery is being used during the power cycle. Thanks. My guess is about 1/3 kw.

There is an important distinction between Energy (which you can measure in kWh or if you want to use SI, Joule) and Power (which is measured in watts or kilo Watts = kW).
Power is dE/dt or simplified energy / time, i.e. the rate at which energy is consumed.

If the power up process on the Leaf would indeed draw energy from the battery at 1/3 kW, then the energy consumed will be 1/3 kW * time to power up.
Lets assume this takes 3s, then the power up process has used up 1 kilowatt seconds.
Note that the battery has ~20 kilowatt hours of energy, when its fully charged.

So in this example, the power up process would use up 1/72000 of the total capacity.
You can test this hypothesis by turning the car 72000 time on and off. Which will
take you exactly 60 h. Have fun!

 

[DaveinOlyWA]

You seem to be missing the point here - my concern is not with the number of bars "used". I'm wondering how much battery is being used during the power cycle. Thanks. My guess is about 1/3 kw.

There is an important distinction between Energy (which you can measure in kWh or if you want to use SI, Joule) and Power (which is measured in watts or kilo Watts = kW).
Power is dE/dt or simplified energy / time, i.e. the rate at which energy is consumed.

If the power up process on the Leaf would indeed draw energy from the battery at 1/3 kW, then the energy consumed will be 1/3 kW * time to power up.
Lets assume this takes 3s, then the power up process has used up 1 kilowatt seconds.
Note that the battery has ~20 kilowatt hours of energy, when its fully charged.

So in this example, the power up process would use up 1/72000 of the total capacity.
You can test this hypothesis by turning the car 72000 time on and off. Which will
take you exactly 60 h. Have fun!

i agree with your statement 100% but he is implying kwh...

 

[klapauzius]

You seem to be missing the point here - my concern is not with the number of bars "used". I'm wondering how much battery is being used during the power cycle. Thanks. My guess is about 1/3 kw.

There is an important distinction between Energy (which you can measure in kWh or if you want to use SI, Joule) and Power (which is measured in watts or kilo Watts = kW).
Power is dE/dt or simplified energy / time, i.e. the rate at which energy is consumed.

If the power up process on the Leaf would indeed draw energy from the battery at 1/3 kW, then the energy consumed will be 1/3 kW * time to power up.
Lets assume this takes 3s, then the power up process has used up 1 kilowatt seconds.
Note that the battery has ~20 kilowatt hours of energy, when its fully charged.

So in this example, the power up process would use up 1/72000 of the total capacity.
You can test this hypothesis by turning the car 72000 time on and off. Which will
take you exactly 60 h. Have fun!

i agree with your statement 100% but he is implying kwh...

Hmmm... 1/3 kWH in say 3s that comes out to..... 400 kW draw on the batteries :shock:
I have always wondered what that smell of burnt plastic was when powering up the car... :lol:

 

[EVDRIVER]

You seem to be missing the point here - my concern is not with the number of bars "used". I'm wondering how much battery is being used during the power cycle. Thanks. My guess is about 1/3 kw.

There is no added energy used worth even noting unless you are one of those people that thinks flicking you lights on and off at home will raise your electric bill. Besides, you don't measure power used in kw, it is kwh.

 

[garygid]

Even 300 watts for a minute is (300 * 1/60) = 5 watt-hours, or only 0.005 kWh of your 21 kWh.

Does the power Off/On use some energy?
Yes, but probably less than leaving the car ON for 5 minutes (or even one minute). Putting the Parking Brake On and then Off again might be the biggest (still VERY small) energy usage.