Hot Weather Range?

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EricCal

Member
Joined
Jul 2, 2017
Messages
7
Hi,

Considering a BEV i3 for family driver in Central California were the summer temperatures are consistently hot. ( June to Sept 85 to 100 degrees with little relief in the evenings). We have a 35 mile round trip into town, so I am thinking the pre-2017 BEV or 2017 60Ah version is fine. We have an SUV and sedan for other needs, so anxiety is really about being able to run into town and back with AC on high.

1.) What impacts can I expect to range in hot weather (90 degrees F + )

2.) What impact could I expect on battery life and charging time? I understand the batteries are liquid cooled, but am concerned about charging in hot garage.

3.) Can someone confirm slower charging would be better for battery in hot weather? (Assuming Type1 and EVSE)

4.) Anyone have experience with how this affects electricity costs?

Thanks this is a very useful forum.
 
The battery pack temperature management system attempts to keep the battery pack cool enough to prevent damage during charging. If, for example, one is charging in an enclosed garage so that heat from the battery pack increases the air temperature in the garage such that it's not possible to keep the pack's temperature low enough, I'm sure the battery management system would reduce the charging rate to keep the pack's temperature in the safe zone.

I don't live in a hot climate, but the A/C compressor has turned on when I have begun charging immediately after driving. Running the A/C compressor to keep the battery pack cool decreases the charging rate and uses more electricity, so I try to avoid charging under those conditions, not because I worry about harming the pack but just to reduce energy consumption. My EVSE has a delayed charging feature, so I can schedule charging to begin after the pack has had a chance to cool a bit. The i3's charging software also supports delaying the start of charging but is less flexible than my EVSE.

Reducing the charging rate would reduce the pack's temperature increase and reduce the likelihood of the A/C compressor running, so it is possible to manage charging to use the least amount of energy.

Unfortunately, I don't have any specific information about how a hot battery pack affects charging time or electricity consumption.
 
Thank you Art. I also found this in answer to #1 re range...

http://www.fleetcarma.com/docs/The-Impact-of-Hot-Weather-on-Electric-Vehicles.pdf

Key points from p 10:
1.) When the heater is used in cold weather, it affects the electric range significantly more than the air conditioning in the
summer.
2.) Component efficiency losses occur as the temperature drops.
3.) Heated garages dramatically increase the cold weather range of electric vehicles.
4.) For those that are heavy users of heating and air conditioning, there is only a small (~1°C) window where HVAC is not used.
5.) A driver’s eco-driving behavior has a large impact at all temperatures.
 
EricCal said:
1.) When the heater is used in cold weather, it affects the electric range significantly more than the air conditioning in the
summer.
The effect of cold weather on electric range can be less with an i3 BEV than it is with the many EV's that use resistance heating including the i3 REx because an i3 BEV uses a heat pump for heating until its efficiency drops at lower temperatures at which point resistance heating is used.
 
I live in Los Angeles. In "good" weather, AKA all months except for summer here, I average around 75 miles. The past couple weeks when it hit triple digits, I've seen the range drop down to as low at 50 miles/charge. (my car is parked outside 24/7). This is a 60ah model.
 
Did a test drive of a 2017 90ah BEV on Sunday. Showed range of 80 miles at a hot 99 degrees. A/C was acceptable.

I'm going to look at the used Tesla S's too. Same age is approx 2x price, but...

FYI.... Tesla has a far more informative website than BMW, specifically in link below they include a range calculator which lets you set outside temp, wheel size and A/C on off setting: https://www.tesla.com/models
 
Lived in Phoenix since 1979. Weather has been around 110*-118* lately. Pull out of garage, turn A/C on and SOC drops 10-15 miles. Driving the speed limit on surface streets, it will recharge as normal. Put in Eco-pro saves a few miles. When I get near my destination I turn the A/C off and get back 7-8 miles and it will still blow cold for a while. Leave car for 10-15 minutes and upon arrival, when restarting, the SOC has dropped 2-3 miles while sitting there. Proceed back home and lose the 10-15 miles when A/C is started. Put in Eco-pro, save a few miles. I have the windows tinted FYI.

Now, what I explain next is odd and I have no good answer why it happens. I will have the temp set at 60* and upon turning to say 70 I LOSE miles!! But there are times I save a few miles. No rhyme or reason, totally random.
Also...I will turn the fan speed down and, you guessed it, I LOSE miles and, again, at times I save miles. No consistency.
When I park the car I set the fan speed to 4 because when you restart and the speed is at 3 and you want a cold blast and you turn it up a speed you will lose miles. By starting at 4 your chances of losing miles are less when switching back to 3.
I know that sounds crazy but I see it every day. Anyone else experience this randomness?

In the winter(it does get into the 30's)when using the heater the miles lost aren't as bad as the summer. YMMV.

One must plan accordingly. I keep it charged. When I have time I have a 50amp fast charger about 5 miles away that I use, mostly at night when it cools down to 98.
 
engineear said:
Lived in Phoenix since 1979. Weather has been around 110*-118* lately. Pull out of garage, turn A/C on and SOC drops 10-15 miles.
If you have a Level 2 EVSE in your garage, have you tried preconditioning the battery pack after setting a departure time just a i3 owners in cold climates do in the winter? I would think that starting with a cool battery pack would increase one's range but at the cost of electricity used for preconditioning. If the additional range isn't needed, it might not pay to precondition.

engineear said:
Put in Eco-pro saves a few miles.
In really hot weather, I'm guessing that you have decoupled ECO Pro from the climate control system so that you get the full climate control power when in ECO Pro. I do that in Honolulu even though temperatures rarely exceed 90º. With climate control decoupled from ECO Pro, the only efficiency gain is the ECO Pro power pedal mapping that makes it easier to drive with moderate acceleration, but if one accelerates in the same manner as when in Comfort mode, there really isn't any efficiency gain and any additional miles of range predicted is just a Guess-o-Meter fallacy.

engineear said:
I have the windows tinted FYI.
I feel a lot of heat radiating down from the roof due to the black CFRP roof absorbing and re-emitting infrared radiation into the interior. With Honolulu's especially high sun angles, I feel that as much heat enters the cabin through the roof as through the windows other than the windshield, so I will be investigating wrapping the roof with infrared-rejecting film if it is suitable for this application.
 
It depends a lot on how much you need to change the temperature...the bigger the delta, the bigger the energy costs. You'll find similar issues if it gets quite cold, the delta T becomes greater. On the REx, since it doesn't have a heat pump, cold is worse energy hog than cooling.
 
Hi All, many thanks for the inputs on several threads

Just back from BMW of Fremont to friant CA. 160 miles. Bought a '14 Rex in Mega with tech/assist for my sons to drive into town from our hill country lair. 18k , 29k with +1yr maint for using their financing at +0.14% over my own for at least 3months

Did entire on initial nearly charge from dealer and one gas fill up. (Got to station with 4 miles left total :D , cause thats how I roll) AC at max the entire time cause it was 100+ degree whole way.

Dealer was fine. Had dedicated "genius" who knew most things. Couldn't help with issue on gas door sticking. Told me to talk to local dealer. Left me son with cell for text questions... which is excellent customer services amongst millenials

Guy coming Tuesday to install a 50a circuit for a Juicebox 40 for $450, device from amazon. Only sad thing is the car only had as fast AC, not fast DC. But realistically, not a thing for me.

Handling on this trip was not acceptable. Too much twichyness. But that is not a thing for a car which will never go further than base charger, in fact will probably never charge outside the home.

More hot weather plates to come!!!
 
Many people dont realize that the battery is cooled by the AC, and in hot weather it will work for a substantial amounts of time. Sometimes I hear the AC compressor kick-in when I turn on the ignition and the temp has been over 90F thru the day. At these temperatures it kicks in every night when I connect the EVSE, even if the car has been sitting for many hours.
 
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