How much power is consumed when we power cycle the car

[yujungchang]

My question is if we need to make a quick stop, within what time range should we turn off the car vs leaving the car on. Sometimes I forgot something and need to go back to pick up, I noticed the bar drop when I just turn it off and start right back on. How you notice this?

We all know booting up the laptop and shutting it down consumes some battery power. When the car is completely turn on, the power indicator seems to say the car is consuming ~400w/h, which translates to 6~7w/min. I don't have any any instrument to measure and only go by the graphical indicator on the screen. When the car is starting up, I assume it will consume more power, as it needs to charge up the circuit and capacitors, especially the ones for the motor. By power cycling the car, how much power is really been consumed and when is better just to leave the car on?

Also how about when we use the carwing to check battery status? I assume the high voltage rail needs to be turned on to check it, as what we did in the car (by pushing power button twice in order to check it from the screen). Will this also consumes the same amount of energy vs turning on the car?

 

[TomT]

The bar drop is due to the BMS recalibrating when you turn the car off, something that it can not do when it is on, not due to power usage. It makes no practical difference in power usage if you cycle the car or leave it on for a short period...

My question is if we need to make a quick stop, within what time range should we turn off the car vs leaving the car on. Sometimes I forgot something and need to go back to pick up, I noticed the bar drop when I just turn it off and start right back on. How you notice this?

 

[planet4ever]

When the car is completely turn on, the power indicator seems to say the car is consuming ~400w/h, which translates to 6~7w/min.

No, watts is power, not energy. The meter is saying that the car is consuming 400 watts. Period. Not per hour or per minute or any other time period, but continuously. You have to multiply watts by a time period to get an energy measurement. So 400 watts would use 2kWh of energy in 5 hours (400 x 5 = 2000 = 2k). However, that meter you are looking at is not really a measurement, but just a computer estimate, based on what devices the computer believes are turned on and how much power it guesses each of them is using.

Ray

 

[yujungchang]

Thanks for clarification on the watt. Without the headlight, it's about 250 watt and it seems to say 350 watt with headlight. Sometimes we are running on low margin and any bit of power saving will help. That is the reason I'm interested in this discussion.

Back to my concern, the distance from my work to home is about 12 miles and it runs up more than 1000ft in the elevation. With the efficient of 3.3miles/kw from carwing log, that translates to 3.6kw. That is about dropping 2 bars and matches to what I generally observed from the dash.

When I break the same trip down into 4 segments, I have ran from 5 bars down to LBW with single bar. This makes me to believe power cycling actually consumes some power than just negligible amount. However since I don't have any instrument, I won't be able to prove that. Wonder if anyone has ability to actually measure the power consumption to tell us how much power is consumed when the car is power cycled? Will power cycle consumes more than keeping the car on, which consumes 250 watt with the head light off?