JimBob
Well-Known Member
- First Name
- James
- Joined
- Jan 26, 2021
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- Location
- Toronto Canada
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- Taycan 4S
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- #1
This is for general knowledge more than anything else.
In my recent highway range test, I found in cold weather, it was necessary to set a departure timer to get the battery hot before leaving to get the best mileage.
I also discovered it was best to leave near to the time set by the departure timer as the battery starts to cool after the timer expires.
You need a hot battery to get the highest range and fastest supercharging times.
How hot is hot? In cold weather, probably above 20C/68F or hotter if possible. If the battery temperature is too low, just driving won't heat it up and it will continue to cool. I had one bad run where the battery temperature started out at 14C/57F with an outside temperature of -12C/10F and then dropped as low as 5C/41F during the trip. Later when I entered traffic and the speeds slowed down the battery heated back up.
The Porsche memo on thermal management of the battery says "Depending on the outside temperature, the battery is preconditioned to a certain temperature level when the vehicle is connected to the mains for charging. The interior can be preconditioned independently of the mains."
So what happens when the vehicle is not connected to the mains and a timer is set.
The Timer runs and draws charge from the battery to heat the battery. I did not test heating the cabin which would be an additional load on the battery. These are the results with the timer set to 4pm and the car off the mains.
Comments
1. If the car is not connected to the mains and a timer is set, the battery will use its charge to preheat it
2. If the air temperature is very cold, this heating is not likely to be very robust and the battery remains cool
3. In this case raising the battery temperature by 7 degrees depleted the battery charge by 3-4%
4. If you have a timer set and do not plug the car in for a long period of time, the timer could run the battery down
5. There are implications for charging strategies
For instance if overnighting without a charger, it would be best to charge the battery first as it will be cool in the morning and will be slow to charge
6. In really cold climates a well insulated garage and heater could be really helpful
7. I wouldn't regard the Indicated Ranges to be accurate
In my recent highway range test, I found in cold weather, it was necessary to set a departure timer to get the battery hot before leaving to get the best mileage.
I also discovered it was best to leave near to the time set by the departure timer as the battery starts to cool after the timer expires.
You need a hot battery to get the highest range and fastest supercharging times.
How hot is hot? In cold weather, probably above 20C/68F or hotter if possible. If the battery temperature is too low, just driving won't heat it up and it will continue to cool. I had one bad run where the battery temperature started out at 14C/57F with an outside temperature of -12C/10F and then dropped as low as 5C/41F during the trip. Later when I entered traffic and the speeds slowed down the battery heated back up.
The Porsche memo on thermal management of the battery says "Depending on the outside temperature, the battery is preconditioned to a certain temperature level when the vehicle is connected to the mains for charging. The interior can be preconditioned independently of the mains."
So what happens when the vehicle is not connected to the mains and a timer is set.
The Timer runs and draws charge from the battery to heat the battery. I did not test heating the cabin which would be an additional load on the battery. These are the results with the timer set to 4pm and the car off the mains.
| Time | Air temp | Battery Temp | Battery Charge % | Indicated Range |
|---|---|---|---|---|
| 7:46am | 4.5C/40.1F | 18C/64.4F | 84% | 290km/180.2m |
| Off the mains and a short trip to the store | ||||
| 11:00am | -2.5C/36.5F | 11C/51.8 | 81% | 281km/174.5m |
| 12:00pm | -1.5C/29.3F | 9C/48.2F | 81% | 282km/175.2m |
| 1:00pm | 0C/32F | 8C/46.4F | 80% | 282km/175.2m |
| 2:00pm | 0.5C/32.9F | 6C/42.8F | 80% | 281km/174.6m |
| 3:00pm | 1C/33.8F | 6C/42.8F | 79% | 278km/172.7m |
| 4:00pm | 0.5C/32.9F | 13C/55.4 | 76% | 267km/165.9m |
| 5:00pm | 0C/32F | 12C/53.6F | 76% | 266km/165.3m |
Comments
1. If the car is not connected to the mains and a timer is set, the battery will use its charge to preheat it
2. If the air temperature is very cold, this heating is not likely to be very robust and the battery remains cool
3. In this case raising the battery temperature by 7 degrees depleted the battery charge by 3-4%
4. If you have a timer set and do not plug the car in for a long period of time, the timer could run the battery down
5. There are implications for charging strategies
For instance if overnighting without a charger, it would be best to charge the battery first as it will be cool in the morning and will be slow to charge
6. In really cold climates a well insulated garage and heater could be really helpful
7. I wouldn't regard the Indicated Ranges to be accurate
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