PreHeat the battery during the winter?

[Rivdog]

Delaying charging until a calculated amount of time prior to departure, would actually save energy vs earlier heating of the lack during charging....losing that heat to environment, and then having to heat back up at time of departure, right?

I think the OP is asking a different question though - I thought OP was asking about preconditioning the battery to have the battery at optimal temperature at the time of departure. The only reason to do that would be to maximize range. If he was setting charging times to coincide with departure times, I guess it might help precondition the battery while simultaneously charging.

However, that would only be true if the battery heats up to the optimal level during L2 charging at the amperage the OP is using. I have no idea as to those variables.

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[R1Tom]

I think the OP is asking a different question though - I thought OP was asking about preconditioning the battery to have the battery at optimal temperature at the time of departure. The only reason to do that would be to maximize range. If he was setting charging times to coincide with departure times, I guess it might help precondition the battery while simultaneously charging.

However, that would only be true if the battery heats up to the optimal level during L2 charging at the amperage the OP is using. I have no idea as to those variables.

I agree. I would love it in my case. Rather than charge up from 10pm till whatever it takes, resulting in some heating at least of the pack at 48amps, and then stopping....cooling till 8am or whatever when I leave...it would be better if it calculated a start time and at least benefit from that free heating.

 

[zefram47]

I'm not quite sure how charging your battery is "wasting energy". You are simply storing energy in the battery. Actually this is LESS wasteful than letting vehicle warm itself up while driving since it ramps up the motors to heat and wastes energy. The act of charging produces the heat needed to warm the system up, so it is a win/win. Worst case, warming the battery while charging will use the same exact amount of energy as warming the battery while driving. Best case, if you charge slowly, you will use 0 additional energy to warm the battery.

I'm not sure why the "if it's already charging that doesn't count" is applicable. I'm sure Rivian's short term solution will be to kick on the charger for a short period of time to condition the cabin/battery, because it is less wasteful than feeding power to the motors to generate heat to warm the system.

It's already been stated that Rivian didn't include a resistive heating element to warm the battery. So the only choice is to warm by charging (not really effective if you're not adding a ton of energy to the pack) or using the motors to generate heat. My point is that it doesn't matter if you're using the motors for heating from the wall or from the battery while driving...it's still going to use the same energy.

As for warming through charging...that would be a relatively easy add from Rivian to make a charge for departure like most other EVs on the market already have. In my case, I can only charge at 24A...so it takes longer to top up than all the folks charging at 48A. While it generates less intense heat, it's also charging/warming longer. The past few days with cold evening temperatures I still haven't had the active conditioning (snowflake icon and hot motors) come on yet, but I also garage park so I'm not losing as much to the atmosphere. My main point was that some people seem to consider grid-tied power draw as not counting while at the same time berating Rivian for their Vampire Drain. It's one and the same because it's still energy pulled from the grid...doesn't really matter when or under what conditions it was pulled.

 

[zefram47]

No heat exchange between the electronics and the battery, cabin and battery heaters were separate circuits.

That's wild. I hadn't realized they changed their design. In my Spark EV there was one resistive heater and one AC compressor, as far as I know. I know there were multiple coolant loops, but in the middle of summer I'd still drive with the windows open and the temperature control turned off on the HVAC. I'd have times over 90F where cold air would start blowing from the vents despite temp control being off because it was trying to chill the battery. Similarly, preconditioning the cabin had the effect of warming the battery too. So even though I'd lose a lot of range (50 vs closer to 80 miles), I never lost regen or acceleration performance.

On the other side, my MINI didn't have any way to warm the battery except through driving. On single digit days I'd see only 50% acceleration capability and between there and 32F/0C would be some ratio of that back to 100%. It was actually a major drivability issue on the coldest days of the year since 90 hp in a 3100 lbs vehicle was kinda slow. Oddly, the car would still get close to 80 miles out of a rated 110 miles on days like that. It would often take more than 15 miles of driving to warm the battery appreciably too.

 

[Craigins]

It's already been stated that Rivian didn't include a resistive heating element to warm the battery. So the only choice is to warm by charging (not really effective if you're not adding a ton of energy to the pack) or using the motors to generate heat. My point is that it doesn't matter if you're using the motors for heating from the wall or from the battery while driving...it's still going to use the same energy.

As for warming through charging...that would be a relatively easy add from Rivian to make a charge for departure like most other EVs on the market already have. In my case, I can only charge at 24A...so it takes longer to top up than all the folks charging at 48A. While it generates less intense heat, it's also charging/warming longer. The past few days with cold evening temperatures I still haven't had the active conditioning (snowflake icon and hot motors) come on yet, but I also garage park so I'm not losing as much to the atmosphere. My main point was that some people seem to consider grid-tied power draw as not counting while at the same time berating Rivian for their Vampire Drain. It's one and the same because it's still energy pulled from the grid...doesn't really matter when or under what conditions it was pulled.

Ok I'm checking out of this conversation since you apparently do not understand the physics involved in electricity and we are talking past each other.

Have a good day.

 

[Dark-Fx]

That's wild. I hadn't realized they changed their design. In my Spark EV there was one resistive heater and one AC compressor, as far as I know. I know there were multiple coolant loops, but in the middle of summer I'd still drive with the windows open and the temperature control turned off on the HVAC. I'd have times over 90F where cold air would start blowing from the vents despite temp control being off because it was trying to chill the battery.

The Bolt has a shared chiller block, but putting heat into anything was not part of that.

 

[LL75]

I think the OP is asking a different question though - I thought OP was asking about preconditioning the battery to have the battery at optimal temperature at the time of departure. The only reason to do that would be to maximize range. If he was setting charging times to coincide with departure times, I guess it might help precondition the battery while simultaneously charging.

However, that would only be true if the battery heats up to the optimal level during L2 charging at the amperage the OP is using. I have no idea as to those variables.

That is correct. get the battery to optimal temperature to maximize range. I see it inmy tesla. Just wondering if Rivian software could do the same.

 

[HyperionMark]

That is correct. get the battery to optimal temperature to maximize range. I see it inmy tesla. Just wondering if Rivian software could do the same.

Point that people are trying to make is that if the heating process isn't done through also charging the battery and/or there is very frigid weather, then the process of preheating the system may take more energy than you'd save once up to temp. Tesla doesn't figure in those "shore power" heating events in the efficiency totals. So yes, it's giving you more range away from the wall, but overall efficiency is similar and probably worse overall per mile when you factor that extra energy in.

 

[WSea]

I leave for work at 3 a.m. on Mondays. We start charging it at 12:00am so that is good information to know this winter. I am in Northern California and while we don't get snow that often where we live, we do get inthe high 20's and low 30's.

This is perfect. Your battery will be at optimal temp range

 

[BigSkies]

I did something that probably makes a bit of a difference, although it was years before I even thought about getting an EV.

I insulated my garage door and put a bunch of R14 insulation in the walls of my unfinished garage.

My garage was previously roughly the same temperature as it was outdoors.

With insulation, my garage doesn’t stay warm by any stretch of the imagination. But it also doesn’t get nearly as cold. It almost never drops below freezing and is routinely 10-15 degrees warmer than the outside temperature when I leave in the morning.

It’s a quality of life thing that probably saves a little energy on heating the cabin. And the battery isn’t quite as cold when starting a trip.

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