Battery Warming while plugged in?

Battery Warming while plugged in?

It has been around 15 deg F in my garage for the past couple of weeks. I have found that my Model S battery will be cold in the morning and I will not have Regenerative braking for about 10 minutes of driving, even though I leave it plugged in all night at 240V (NEMA 14-50). I thought the battery was supposed to stay 'warm' while it is plugged in.
I have 4.1 software and use the 'sleep mode' where the displays are not powered when not in use. I wonder if the whole car 'goes to sleep' and quits warming the battery once it is fully charged. This might explain the cold battery, even though fully charged and plugged in. Could this be a quirk of the 4.1 software? Has anyone else noticed this.

jat | 14 janvier 2013

The battery stays warm enough not to damage it, but you don't want it wasting energy unnecessarily. It can also make your battery a bit below maximum charge, because the way it works is it will periodically wake up to recharge the batteries after it has completed charging, but the battery heater runs whenever the batteries need heat.

STEVEZ | 14 janvier 2013

Assuming your car is fully charged to Standard overnight, one trick some owners have been using is to start a Range mode charge at low current half an hour or so before heading out for the day. It'll add just a few miles of range, not enough to harm the battery, and your battery will be warm when you unplug and go.

djp | 14 janvier 2013

Does anyone know if the need to keep the battery warm is to make sure it is ready to go when you are?

Where I am going with this is that we now have deep sleep where lots of extra stuff is shut off, to save power consumption, if you are willing to wait for a system power up.

How about a storage mode where everything possible is shut down (includes battery warming) with the understanding that when you are ready to go the MS will need time to warm up. Would be very useful for leaving it at a cold airport (or driveway) for a day or 4 or 14).


dborn | 14 janvier 2013

You don't want liquids to freeze......

HansJ | 14 janvier 2013

@dborn - isn't that what Ethylene Glycol is for? The antifreeze in the radiator of an ICE doesn't freeze at the airport. I'm pretty sure the liquid coolant around the battery pack is not plain water.

Brian H | 15 janvier 2013

When on "shore power", conserving energy is not relevant. jat, until "the app" is available, the "periodically" is unpredictable, and the odds are it won't be when you want to leave. So you're likely to start out cold, and maybe short of charge. Slow charging will work best till you can specify the start and stop and level.

jat | 15 janvier 2013

@HansJ - depends on how cold it gets. I remember in Alabama one time when it was well below zero and people that didn't put a blanket over their radiator or pull them up next to their house to keep the wind off the radiator were getting frozen radiators. I'm sure that is a bigger problem up north, though they probably mix the antifreeze for the colder climate.

jat | 15 janvier 2013

@BrianH - slow charging has the same problem - you have to get the start time exactly right or either it already finished and is cold or it didn't get the level of charging you want.

When it was cold enough to give me the dashed line in the morning, it only took a few minutes to get full power/regen, and what was available was sufficient anyway.

DocDog | 15 janvier 2013

I suspect that the beta testers of the mobile app cannot tell us, but it seems likely that when you pre-heat the cabin from the app, that the car will warm the battery as well. I notice that with the Volt, the "remote start" feature (as they call it) will draw about 3 kW and warm both the cabin and the battery.

Brian H | 15 janvier 2013

you're not trying to get exactly the level you want.
1. Enough
2. Not "range filled" (overfilled, so that regen is off, etc.)

So assuming you don't need a "full" battery, you've got at wide target to hit. If you need, say 150 mi., anything between 150 and 250 is fine, and should be easy. Remember, you can set the draw at any amperage you want, from 5 (enough to keep the battery warm and maybe add 1 mi/hr of range) and your peak (say, 40 which might give you 30 mi/hr range and stop filling in under 5 hrs, thus allowing the battery to then begin cooling). Set the level that gives you you (say) 200 miles in 16 hrs, but stop it after 12 hrs in the morning and you have 150 miles range added. You might take a few days to get it right, so allow extra the first few days.

Brian H | 15 janvier 2013

typo: " a wide target..."

olanmills | 15 janvier 2013

@DocDog, I'm pretty sure you're right, because when the battery gets very cold, a message displays on the center console telling you that the battery is cold and that full power may not be available. It recommends that you plug in if possible, but it also recommends that you use the (non-existant) mobile app to pre-heat the car about 30 minutes before you want to drive, and it says that this will also activate the battery heater.

So, the UI even today, without the mobile app available, confirms what you just said.