Cabin heat from ICE

[Ryan]

Does the cabin heater draw power from the EV battery while driving in ICE mode after the engine has been adequately warmed up? How about if you have a warm ICE but driving in EV mode?

 

Some context to my question. I drive at city speeds for 10 mins to reach the highway. Then drive highway speeds for 90 mins. Another 10 mins at city speeds to reach my destination. I'd like to save my EV energy for city driving, and know that I'm not consuming it while heating the cabin on the highway. 

 

 

[murphy]

If the ICE water temperature is warm enough to warm the cabin it is used.  If it is not warm enough the valve is closed and only heat from the 5000 watt resistive heater is used.

 

Put the car in EV Later mode when you reach the highway to save the battery for later use.  EV Later makes the car operate in hybrid mode.  Switch back to EV Now mode when you leave the highway.

 

I drove a 2013 Energi from April 2013 until June of this year when I traded it in on a 2021 Mach-E.  I never put it into Auto mode the entire time.  Auto uses the battery first and switches to hybrid mode when the battery is depleted.

Edited December 3, 2021 at 09:59 PM by murphy

[theterminator93]

 

Here is what I do to minimize wasted battery on heat in the winter where mixed highway/city driving is involved...

 

1. Use Go Times to preheat the car prior to your departure. This will warm up the cabin without leaving you with a partially discharged battery prior to your departure.
2. After you turn on the car, immediately switch from EV Auto to EV Now and be sure the HVAC is off. If you need a little extra warmth, use the heated seat. This will ensure the ICE stays off unless it is extremely cold out. The ICE will turn on with the heater enabled below certain temperatures; that temperature threshold is lower in EV Now mode vs. EV Later; the best way to prevent ICE startup is to leave the heat off and use EV Now. Be advised though - if it's extremely cold out, the ICE will turn on for other reasons regardless of those settings. If the windows start to fog after a few minutes, I usually crack the sunroof and the cool, dry air entering the car clears them up without making me excessively cold. I've noticed a preheated cabin (via Go Times) leaves the car more susceptible to window condensation than a cold car - YMMV.
3. As you approach the freeway on ramp (for me, usually about 500' as I'm decelerating to make the turn), switch to EV Later mode. Whatever the remaining capacity the HVB is at this point, the vehicle will target as its set point during your trip down the freeway.
4. As you depress the throttle and move past the EV power limit of hybrid operation, the ICE will start and initially idle for about 1 minute. During this time, the ICE is not powering the vehicle but cycling the oil and warming itself slightly; the battery will continue to provide the power required to accelerate to speed. After that minute or so, the ICE will rev up to the most efficient RPM for your speed/throttle combination, and take over 100% of the power production for the vehicle. After it does, it will divert the excess power produced to start recharging the HVB to the set point percentage when you switched from EV Now to EV Later.
5. After 2-3 minutes or so you will have warmed the coolant in the engine sufficiently to be able to turn on the HVAC and heat the cabin normally without having used any HVB for the process. Once the battery gets recharged by the engine to within 2-3% of the set point, it will allow the ICE to stop when the power demands drop sufficiently (per normal hybrid operation), and the charge/discharge cycle inherent to hybrid mode will prevail for the remainder of your freeway commute.
6. After you get off the freeway and decelerate, switch back to EV Now mode. You should have the same (or very close to the same) HVB percentage as you did when you switched from EV Now to EV Later when you got on the freeway.
7. In EV Now mode, the electric heater (if left on) will draw power from the HVB as needed to maintain a minimum coolant temperature in the heater core. Initially the electric heater will be off, but as cold outside air is drawn in and passes over the heater core, it will cool and the electric heater will need to turn on to keep the coolant warm enough for your cabin heat settings. You can minimize the amount of power used as a result of this by choosing to recirculate the already warm interior air or just leaving the HVAC off until you reach your destination.

It's your responsibility to choose exactly how you will choose to drive based on your own circumstances; my guide here is just an example of what you could do based on what I have chosen to do. Remember that if you elect to keep HVAC off to conserve battery, vent the car as is necessary to keep the windshield clear of condensation.

 

 

On 12/3/2021 at 9:04 AM, murphy said:

 5000 ohm resistive heater

 

Wouldn't it be 5000 Watts?

[murphy]

On 12/3/2021 at 4:37 PM, theterminator93 said:

 

Here is what I do to minimize wasted battery on heat in the winter where mixed highway/city driving is involved...

 

1. Use Go Times to preheat the car prior to your departure. This will warm up the cabin without leaving you with a partially discharged battery prior to your departure.
2. After you turn on the car, immediately switch from EV Auto to EV Now and be sure the HVAC is off. If you need a little extra warmth, use the heated seat. This will ensure the ICE stays off unless it is extremely cold out. The ICE will turn on with the heater enabled below certain temperatures; that temperature threshold is lower in EV Now mode vs. EV Later; the best way to prevent ICE startup is to leave the heat off and use EV Now. Be advised though - if it's extremely cold out, the ICE will turn on for other reasons regardless of those settings. If the windows start to fog after a few minutes, I usually crack the sunroof and the cool, dry air entering the car clears them up without making me excessively cold. I've noticed a preheated cabin (via Go Times) leaves the car more susceptible to window condensation than a cold car - YMMV.
3. As you approach the freeway on ramp (for me, usually about 500' as I'm decelerating to make the turn), switch to EV Later mode. Whatever the remaining capacity the HVB is at this point, the vehicle will target as its set point during your trip down the freeway.
4. As you depress the throttle and move past the EV power limit of hybrid operation, the ICE will start and initially idle for about 1 minute. During this time, the ICE is not powering the vehicle but cycling the oil and warming itself slightly; the battery will continue to provide the power required to accelerate to speed. After that minute or so, the ICE will rev up to the most efficient RPM for your speed/throttle combination, and take over 100% of the power production for the vehicle. After it does, it will divert the excess power produced to start recharging the HVB to the set point percentage when you switched from EV Now to EV Later.
5. After 2-3 minutes or so you will have warmed the coolant in the engine sufficiently to be able to turn on the HVAC and heat the cabin normally without having used any HVB for the process. Once the battery gets recharged by the engine to within 2-3% of the set point, it will allow the ICE to stop when the power demands drop sufficiently (per normal hybrid operation), and the charge/discharge cycle inherent to hybrid mode will prevail for the remainder of your freeway commute.
6. After you get off the freeway and decelerate, switch back to EV Now mode. You should have the same (or very close to the same) HVB percentage as you did when you switched from EV Now to EV Later when you got on the freeway.
7. In EV Now mode, the electric heater (if left on) will draw power from the HVB as needed to maintain a minimum coolant temperature in the heater core. Initially the electric heater will be off, but as cold outside air is drawn in and passes over the heater core, it will cool and the electric heater will need to turn on to keep the coolant warm enough for your cabin heat settings. You can minimize the amount of power used as a result of this by choosing to recirculate the already warm interior air or just leaving the HVAC off until you reach your destination.

It's your responsibility to choose exactly how you will choose to drive based on your own circumstances; my guide here is just an example of what you could do based on what I have chosen to do. Remember that if you elect to keep HVAC off to conserve battery, vent the car as is necessary to keep the windshield clear of condensation.

 

 

 

Wouldn't it be 5000 Watts?

Yes it should be 5000 watts.  I must have been half asleep when I typed that.  I fixed the error.

Edited December 3, 2021 at 10:00 PM by murphy

[jsamp]

On 12/3/2021 at 1:37 PM, theterminator93 said:

3. As you approach the freeway on ramp (for me, usually about 500' as I'm decelerating to make the turn), switch to EV Later mode. Whatever the remaining capacity the HVB is at this point, the vehicle will target as its set point during your trip down the freeway.

 

I do a variation on this.  I hit try to hit "EV Later" to fire up the ICE 30-60 secs before I hit the freeway onramp.  This is to avoid using the battery to accelerate to 65 (a very high battery drain rate).  Then when I reach the onramp the ICE is already warmed up and takes over.  Unfortunately sometimes that means sitting at a stoplight with the ICE on, depending on the situation.