Battery thermal management system

[magudaman]

I know that the cabin heater has two 5 kilo watt heating elements. Since level 1 charging can't supply this level of power the difference has to come from the battery pack.

I wonder why they use so much power?

I have a space heater (in my house) that plugs into 120V and surely doesn't draw more than 12 amps. That's only 1440 watts. If that thing was turned on full blast inside the confines of my FFE cabin, it would roasting in there within 10 minutes.

Any idea why the FFE needs two 5000 watt heating elements?

You need a lot more watts to heat and cool a vehicle. Vehicles are not very well insulated since they have lots of single pane glass and are leaky to outside air flow. Most car air conditioners are around 15,000 BTUs or more which is about ~4400 watts of heat movement. We also own a Think City which has a 3kw heater and when it is below 30F it really can't keep up!

I keep reading that our vehicle has 10kw available but it seems to level out at 5kw very quickly after start up.

 

[EVfuture]

Hello,

I understand that TMS works while the car is being operated or plugged in and charging, but does it also work if you're plugged and waiting to value charge during off-peak hours?

Thanks!

 

[EVfuture]

Oops, I see WattsUp on page 1 seems to have answered my question. Any new info or disagreement?

 

[sefs]

I know that the cabin heater has two 5 kilo watt heating elements. Since level 1 charging can't supply this level of power the difference has to come from the battery pack.

I wonder why they use so much power?

I have a space heater (in my house) that plugs into 120V and surely doesn't draw more than 12 amps. That's only 1440 watts. If that thing was turned on full blast inside the confines of my FFE cabin, it would roasting in there within 10 minutes.

Any idea why the FFE needs two 5000 watt heating elements?

You need a lot more watts to heat and cool a vehicle. Vehicles are not very well insulated since they have lots of single pane glass and are leaky to outside air flow. Most car air conditioners are around 15,000 BTUs or more which is about ~4400 watts of heat movement. We also own a Think City which has a 3kw heater and when it is below 30F it really can't keep up!

I keep reading that our vehicle has 10kw available but it seems to level out at 5kw very quickly after start up.

The reason the heater element has to be so powerful compared to a space heater in your house has to do with recirculation. In your house, the space heater is recirculating the air. In your car, fresh air is brought in while heating. If you set your HVAC to recirculate during heating, fogging occurs very quickly. So to eliminate this issue, the car brings in fresh air. This air is whatever the outside air temperature is. Heating up freezing air to a comfortable temperature takes a lot of power.

 

[unplugged]

If you set your HVAC to recirculate during heating, fogging occurs very quickly. So to eliminate this issue, the car brings in fresh air. This air is whatever the outside air temperature is. Heating up freezing air to a comfortable temperature takes a lot of power.

So I wonder if you set the A/C to "recirculate" and the turned the defrost on so the humidity is removed, whether this might make the heater more efficient?

 

[sefs]

So I wonder if you set the A/C to "recirculate" and the turned the defrost on so the humidity is removed, whether this might make the heater more efficient?

I had the same thought and tried this, but it didn't seem to help too much. I suspect that even though you have A/C ON on the HVAC controls, when it's very cold it turns itself off (I did my experiment when it was cold and the windows still fogged.). You can play with this one yourself by putting up the screen that shows Climate energy usage and trying different settings. I have noted that overriding the fan to its lowest setting uses less energy because the heater isn't having to heat as much of a volume of cold air.