Bad battery heater?

[Andyw2100]

Temps were in the 30s this morning. I had to swing over 5 miles from our hotel to a SpC so I pre conditioned the car for about 30 minutes prior.

Battery did NOT heat whatsoever. Even after 15 minutes of charging the rate was limited to 60 kW (I was at 33% SOC). Tesla tech support claimed the battery was at 18 C and no faults were showing. Did 7.0 disable the battery heater altogether?

Did you have range mode on? With range mode on, the battery will not heat with cabin heating.

 

[Jason S]

7.0 is pretty different wrt battery heating and regen. I didn't know that also limited the Supercharging.

Thanks for the info.

 

[FlasherZ]

Temps were in the 30s this morning. I had to swing over 5 miles from our hotel to a SpC so I pre conditioned the car for about 30 minutes prior.

Battery did NOT heat whatsoever. Even after 15 minutes of charging the rate was limited to 60 kW (I was at 33% SOC). Tesla tech support claimed the battery was at 18 C and no faults were showing. Did 7.0 disable the battery heater altogether?

I assume you're talking about during pre-conditioning only. That I'm unsure of, but I know the battery heater does work.

Driving back this weekend, as I was arriving in Knoxville, TN, it was getting too late for us to stop in to the Supercharger to charge prior to hitting the hotel (which was about 15 miles further north of us) - winds and temp forced me to stop rather than stretch it into the Knoxville SC. I made sure I had enough mileage coming out of Chattanooga to drive the extra 15 miles to the hotel and 15 miles back in the morning, with 10 miles for overnight vampire loss (just in case).

The next morning, we piled in the car and started driving (I made sure to park facing east so the rising sun could help). As I pulled off I-75 and stopped at the light for the SpC, even with the climate control off I could see the car was consuming > 5 kW, presumably to heat the battery. After that 15-mile drive, the SpC started charging at only 250A (instead of the 330+ you'd expect from a car with 15 miles remaining).

I wish I had something more definitive from my data collection, but TeslaMS stopped working about a month ago and I just got it working again after my trip this weekend. Last record I have of battery_heater_on is 3/29/2015, pre-7.0.

 

[apacheguy]

Did you have range mode on? With range mode on, the battery will not heat with cabin heating.

I have never enabled range mode precisely for this reason.

The next morning, we piled in the car and started driving (I made sure to park facing east so the rising sun could help). As I pulled off I-75 and stopped at the light for the SpC, even with the climate control off I could see the car was consuming > 5 kW, presumably to heat the battery. After that 15-mile drive, the SpC started charging at only 250A (instead of the 330+ you'd expect from a car with 15 miles remaining).


I wish I had something more definitive from my data collection, but TeslaMS stopped working about a month ago and I just got it working again after my trip this weekend. Last record I have of battery_heater_on is 3/29/2015, pre-7.0.

Perhaps if I had driven more the result would have been better. Driving 3 miles down the road I did not observe/don't recall aggressive power consumption that would have indicated the battery heater was active. Still, 250 A is a LOT more than I ever observed during that session. At the outset I was at more like 100 A.

I didn't think about the API parameter until it was too late. Good thought, though.

Thinking about this some more, I also noted that the dashed power limiters did not budge from the time we got in the car to the time we plugged in.

 

[Oba]

Another thing to consider is that sometimes you don't want the battery to warm up when you remotely heat your cabin.

If you pull over to a rest area for a few hours shut-eye because you just can't focus any longer, you might use the remote access to run the heater for 30 minutes at a time, but you don't want the battery drawing extra power to heat itself while you're sleeping. Other option would be to keep your door open, but that's ill-advised while sleeping in a strange rest area.

Also, smart preconditioning, when enabled, warms your cabin because the car thinks you will be using it soon. If you don't really use it, you don't want to waste the battery heating the battery. Same applies if you intentionally enable the cabin heater but you don't leave when you intended.

My point is, I can definitely see why Tesla would not fully heat the battery to optimal driving temperature when you're not really driving.

Just use "camping" mode... no battery heater, no waking up every 30 minutes to restart the heater.

Car to neutral, then manually apply parking brake. Don't forget to lock the doors while you snooze.

 

[Kalud]

I assume you're talking about during pre-conditioning only. That I'm unsure of, but I know the battery heater does work.

Driving back this weekend, as I was arriving in Knoxville, TN, it was getting too late for us to stop in to the Supercharger to charge prior to hitting the hotel (which was about 15 miles further north of us) - winds and temp forced me to stop rather than stretch it into the Knoxville SC. I made sure I had enough mileage coming out of Chattanooga to drive the extra 15 miles to the hotel and 15 miles back in the morning, with 10 miles for overnight vampire loss (just in case).

The next morning, we piled in the car and started driving (I made sure to park facing east so the rising sun could help). As I pulled off I-75 and stopped at the light for the SpC, even with the climate control off I could see the car was consuming > 5 kW, presumably to heat the battery. After that 15-mile drive, the SpC started charging at only 250A (instead of the 330+ you'd expect from a car with 15 miles remaining).

I wish I had something more definitive from my data collection, but TeslaMS stopped working about a month ago and I just got it working again after my trip this weekend. Last record I have of battery_heater_on is 3/29/2015, pre-7.0.

I've been playing with this in the last two weeks. The battery heater is indeed rated for 450V / 5556W / 12.3A. And observing a cold battery (-10C) with and without range mode you can see battery_heater_on toggle which is also quite visible in the dash energy consumption (about 5kW). I still have some tests to do on much colder temp, but at -10C, starting driving with range mode ON is doesnt start the battery heater (thus conserving energy). Toggling Range Mode OFF starts the heater. I find it useful to run with range mode ON initially and start the heater (with range mode OFF) a bit before arriving at destination where I would charge to get the battery above 0C and allow charging. Its pretty consistent with the Supercharger operating at lower power until the battery is up to temperature.



- - - Updated - - -

Here's the data graphically:

I started the heater 5 min before arriving at my destination to charge with a -12C battery, no heater initially on my drive until I switched off range mode.

 

[apacheguy]

Does anyone know if SpC raises the active heating target on the BMS? If not, that could explain why it took so long for me to climb from 40 kW to 72 kw. IIRC, the nominal active heating target is 8 C (roughly 45 F). At this temp the battery is still too cold to accept anything near 100 kW. So my guess as to what happened is that perhaps the heater briefly enabled and then switched off at 8 C. Then heat dissipation from SpC (arguably much slower especially when only 40 kW are going in) was relied upon to get the pack up to optimal temp.

I disagree with this engineering design. The battery heater should activate at full tilt when connected to a SpC until the pack is at optimal charging temperature.