Power in Cold Weather

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blacknj

Member
Joined
Jun 10, 2016
Messages
6
Has any else noticed the power/regen bar in the dash under the speed is limited in cold weather? Today was under freezing and I was parked outside and until about 15 miles into my journey the acceleration was limited to about half power. It started to increase in increments after that.
 
I did not precondition. I figured it is normal but I was wondering if anyone had any more info into how it works, like what temperature is the cutoff.
 
blacknj said:
I did not precondition. I figured it is normal but I was wondering if anyone had any more info into how it works, like what temperature is the cutoff.
Near as I can tell, about 72F. Cooler, preconditioning warms the car. Hotter, preconditioning cools the car.

A better question is 'what should the preconditioning time be?'

Near as I can tell, about 20 minutes before you actually leave. The reason is the car will draw battery power to reach the target temperature at the designated time. But it looks like leaving about 20-30 minutes later allows the L1 charger to bring the battery up to 100% while the cabin and car are close enough to be comfortable and usable at peak efficiency.

Bob Wilson
 
I think it is a little misleading, but for optimum operation, you need to set a departure time. That is the only thing that will warm up the battery pack. While doing that, you can choose to also precondition the cabin. You can only set a departure time if you have the car plugged in. The level 1 EVSE sold with the car in the USA cannot keep the battery fully charged if you opt to set a departure time, but it's probably a wash in that because it spent some energy warming the battery and uses more than the EVSE can provide, what's lost in the SOC is probably made up about equally by the warmer battery. I've seen my car drawing over 20A during a departure time and preconditioning session...more than a level 1 EVSE can provide.

A cold battery can limit both getting energy out as well as putting power into the battery pack. If the car determines it can't put the full amount of energy into the batteries, it will use the actual brakes instead. They've done a pretty good job of balancing them with the regen, but it's not perfect.
 
Preconditioning slowly warms the battery to 10degC. Somewhere between 10 and 4degC the power, charge time and regen is affected. It's battery cell temperature rather than ambient temperature although low ambient will increase your heating load.

Preconditioning the cabin takes about 20mins or so whilst battery preconditioning takes up to 3 hours.
 
I'm in Toronto Canada in an apartment and can never precondition. At work I have to park outside. In the winter it's regularly sub-0 degrees C here and i've never seen a power reduction in cold weather with or without preconditioning -- certainly a range loss, but never a lack of access to power for acceleration or speed.
 
If you feel the car is sluggish in cold condition, most likely is the tire pressure. I park outdoor and when temp drop below freezing, I can feel the car won't handle as good. I got a cheapo digital tire inflator - which will shut off at preset pressure and check pressure regularly. This makes a big different.
 
A cold (or excessively hot) battery cannot accept or supply power as readily as one in the 'zone', so recharging can be slowed as a result. The discharge is not as efficient when it is cold, so you might notice a difference if you were trying to really push the car.

Terminology can be confusing, but in the i3 lexicon, preconditioning is for the cabin only...to get optimum range, you need to set a departure time and have the car plugged into an EVSE to warm the batteries. That has a 1Kw resistance heater, and will try to warm the batteries to between 10-20C...the logic will turn that on up to 3-hours prior to your set departure time. If you also choose to have the cabin conditioned (heat or cool), then that will start about 20-minutes prior and maybe extend a bit after your selected departure time. That is a separate 'tick box' on the departure menu. Preconditioning the cabin can take a draw of over 2Kw, then add the 1Kw for the batteries, and your load will easily exceed the level 1 EVSE supplied in the USA, so you'll leave with less than a full battery. With the EVSE sold for countries with 230-240vac that comes with the car, you'll still potentially go backwards a little, but might not, depending on the ambient temperature when you ask it to run.
 
I nitoced the power band meter was reduced one cold morning when I was driving to work, first time I noticed this. Didn't really notice a reduction in power but I was driving conservatively. I've driven in colder conditions and haven't noticed this on the display. Did not precondition the car before driving.

One note about preconditioning, I recently purchased a Juicebox Pro (which I'm loving) and notice if I set a departure time the EVSE charges the car, no power sent after, and then I notice more power sent starting about 30 minutes before departure. I'm assuming this is for the cabin climate control but I thought the batteries also preconditioned or the car completed the charge cycle for an hour or two before departing, at least that's what I've read on multiple threads. I set the departure time the night before so I've allowed plenty of time. But according to my Juicebox, I don't see any real difference between setting a departure time or activating climate control shortly before leaving since, according to the power graph in the Juicebox app, nothing is happening an hour or so before departure time. If all the post I've read are true, shouldn't the car finish the charge cycle shortly before the departure time so the battery cells are warmer?

Below is a link to an image showing the reduced power band. Can't find a way to upload images to this forum even after searching. Note, picture taken on a rural road with no traffic around.
https://drive.google.com/file/d/0BzKslr_dzJ1FSWh4MEZxY09SYUk/view?usp=drivesdk

And here is a link to an image showing charge activity. Departure time set and plugged in the night before.
https://drive.google.com/file/d/0BzKslr_dzJ1FYjBCeWx3c2k4d28/view?usp=drivesdk
 
Setting a departure time will try to warm the batteries up to at least 10C. Depending on where the car is parked, the ambient temperature, and when it was charged (that warms the batteries, too), the batteries might be warm enough to not need any conditioning. The heater is a 1Kw electric resistance pack buried in the bottom of the battery compartment. The batteries have a lot of mass, and will hold any heat they have for awhile, and that can help, too, when it's cooler.

If you select to precondition the cabin as part of a departure time, that generally starts about 20-30 minutes prior to your set departure. Warming the batteries can start as much as 3-hours before. The car doesn't immediately turn on the EVSE once there's a load from departure battery warming or cabin heating, but only once the SOC drops a bit. Depending on whether you have a BEV or REx and the temperature will also affect how much power it takes...the BEV has a heat pump to use when it's cold, the REx does not. The BEV is quite a bit more efficient in heating mode as a result.
 
I noticed only a few bars available on the power band this morning on my drive in. The car had been sitting outside for over a day and was connected to the EVSE prior to that. The batteries definitely don't like the cold weather, especially when they haven't been charged in over a day.
 

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