Heater = 9kW

[boltage]

Did another drive on a long flat freeway with cruise control at 65mph.

Heater off = 18kW
Heater on = 27kW (48F outside, temperature set to 72F)

Heated seats on or off made no difference.

 

[CGameProgrammer]

The power draw for heated seats and/or steering wheel appears to be negligible which is why it's best to only use heated air to warm up the cabin, then turn it off and rely entirely on the seat and wheel heating. Of course rear-seat passengers would still need occasional heated air.

 

[Zoomit]

This is helpful info.

Was there any wind? What was the elevation?

 

[LeftieBiker]

There are HVAC use tips and techniques that can reduce heater draw a lot, while still providing heat. The first is to find which vent modes allow recirculation of air, and use those as much as possible, in frigid air temps. Second is to look for a "partial recirculate" or "mixed recirculate" mode that lets you reheat most of the cabin air, while still bringing in enough fresh air to prevent fogging and frosting of windows. The Leaf has a partial recirculate mode that was only "discovered" last year, believe it or not - it wasn't well documented, to say the least.

 

[boltage]

This is helpful info.

Was there any wind? What was the elevation?

No apparent wind at the time. Not much elevation. For those in the SF bay area, it was the flat part of the Hayward - San Mateo bridge.

 

[Zoomit]

Ok thanks. I was just looking to help validate my energy consumption model. At 48F and sea level, it predicts 17.5kW without HVAC so it seems pretty close.

 

[like2bike]

I can't believe the heat will use 9 KW. This is out-of-whack with the power my LEAF uses. I am able to display heat and A/C KWs on an Android app using data from the OBD-II connector. Here is what is am seeing. And it just happens to be 47 degrees in my garage tonight. This power doesn't include the 12V fan and I am not using recirculate. The power is provided in 0.25 KW increments.

Peak power with heat blasting: 2.75 KW (this was only momentarily and the power started dropping.
72 F setting: 1.75 KW (I don't think I ever got the temp stabilized, but stayed at this temperature for maybe 5 minutes)
66 F setting: 250-500 KW (It seemed to have stabilized to this power. The car had been preheated to 72, but this was the power after being at 66 for about 10 minutes.)

 

[Zoomit]

The Spark EV heater uses about 6 kW so 9 kW for the Bolt EV, with a larger cabin volume, doesn't sound unreasonable.

Another data point is that the Cabin Heater and Cooler Module (CHCM) is connected to the High Power Distribution Module (HPDM) via a 30A breaker. At a low battery voltage of ~325V, that breaker would trip at 9.75kW [325x30].

 

[GetOffYourGas]

Another reference point - my 2012 Leaf (without heat pump, with a fluid-based heater) draws up to about 6kW until the cabin is warm. At 47F, it would drop to about 1.5kW in steady-state to maintain a cabin temperature of 65F.

My Leaf's heater is good but not great. I could believe that GM put a 9kW heater in the Bolt, but I would expect it to crank out lots of hot air (and quickly, too). Possibly one of the best heaters I've ever experienced in a car.

 

[michael]

My Focus Electric used 6 kW for the heater running full blast.

The use of a resistive heater in the Bolt rather than a heat pump is in my opinion the most glaring failure. Won't stop my from getting one, but it was a big mistake that will hurt sales in cold areas.

If Nissan, Kia, and BMW could use a heat pump, why couldn't Chevy?

 

[michael]

I can't believe the heat will use 9 KW. This is out-of-whack with the power my LEAF uses. I am able to display heat and A/C KWs on an Android app using data from the OBD-II connector. Here is what is am seeing. And it just happens to be 47 degrees in my garage tonight. This power doesn't include the 12V fan and I am not using recirculate. The power is provided in 0.25 KW increments.

Peak power with heat blasting: 2.75 KW (this was only momentarily and the power started dropping.
72 F setting: 1.75 KW (I don't think I ever got the temp stabilized, but stayed at this temperature for maybe 5 minutes)
66 F setting: 250-500 KW (It seemed to have stabilized to this power. The car had been preheated to 72, but this was the power after being at 66 for about 10 minutes.)

Because even Nissan was smart enough to use a heat pump starting in 2013

 

[EldRick]

9kW is hard to believe: the equivalent of six large space heaters to warm a small car?

 

[Zoomit]

It's a peak load that diminishes over the period of 10's of seconds depending on conditions.

 

[GetOffYourGas]

9kW is hard to believe: the equivalent of six large space heaters to warm a small car?

A car loses heat quickly as it drives through cold air. Plus, it may have to be warmed up from below zero to 70F in a reasonable amount of time. Neither of those are battles fought by a 1.5kW space heater placed in a small room.

I'm not sure why 9kW is so hard to believe given that it is known that both the Leaf and Focus EV have 6kW heaters.

 

[JeffN]

A knowledgeable GM employee has previously written that the Bolt EV's electric heater is 7.5 kW.

It's possible you are seeing 9 kW because when you enable the A/C system it is also detecting excess humidity that could fog up the windows as part of the "Auto Defog" feature and is also routing some power to the A/C compressor.

Try your experiment again but first go into the vehicle configuration screens and disable "Auto Defog".

 

[LeftieBiker]

Because even Nissan was smart enough to use a heat pump starting in 2013

The S does not have the heat pump, and even the models with it have to use resistance heat below about 25F. Below 15F the heater draw is the same as for a non heatpump-equipped Leaf.

 

[michael]

Because even Nissan was smart enough to use a heat pump starting in 2013

The S does not have the heat pump, and even the models with it have to use resistance heat below about 25F. Below 15F the heater draw is the same as for a non heatpump-equipped Leaf.

Many people have used the argument that a heat pump doesn't work at very low temperatures as a justification for using resistance. It may well be true that resistance is needed as a pre-heater in very cold climates, but even here in California the resistive heater is an energy waste. How about providing a heat pump standard, and a resistive pre-heater as a "cold weather" option. Or make a heat pump an option, like Nissan did. Given a choice between that and DCFC, I'd pick a heat pump.

The point being that, using your example, between 15 F and 60 F the heat pump does better than the resistive heater.

Somehow Nissan, Kia, and BMW made a heat pump work.

 

[Zoomit]

It's certainly an interesting engineering trade. Instead of the cost of a heat pump, I think I'd rather have another kWh or 2 of battery capacity to use with a resistive heater. That's much more flexible to me.

 

[dndrich]

So, is it certain then that the heater in the Bolt is resistive? I have not seen details on that.

 

[LeftieBiker]

So, is it certain then that the heater in the Bolt is resistive? I have not seen details on that.

GM has made no claim for a heat pump, so its' virtually certain that there is none. If there were, then the heater power draw would be about the same at 45F as the A/C power drain is at 75F. They do seem to claim some sort of motor heat recovery subsystem.