Manual Preconditioning of the Battery to Improve Cold/Hot Weather Efficiency

[dleepnw]

As we enter the winter season and the temps drop, I'm reminded again how range/efficiency drops in the cold weather.

I think I read somewhere that allowing us to manually precondition the battery is on the product roadmap. I know if the battery is warm it will be more efficient in cold weather and vice versa in hot weather. Any ideas as to how much more efficient? Does any one know what the ideal battery temp is? Hopefully Rivian can provide some guidance.

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[Osyras]

On Gen1 you can pre-heat using scheduling as heating the cabin also heats the battery. On Gen 2 however we are stuck until they release an update...which if I had to guess was planned for Fall 2024

 

[Riviot]

On Gen1 you can pre-heat using scheduling as heating the cabin also heats the battery. On Gen 2 however we are stuck until they release an update...which if I had to guess was planned for Fall 2024

Scheduling cabin precondition does not condition the battery directly. There's indirect cabin heat (floor vents) that will warm it, but not a lot. If the vehicle gets too cold and is plugged in, it'll turn on the floor vents to warm up.

 

[DayTripping]

Couldn't you just trick it and tell it you wanted to go to a nearby fast charger to charge? I used to do that with my Teslas.

 

[R1TCntrlMaIzzy]

Couldn't you just trick it and tell it you wanted to go to a nearby fast charger to charge? I used to do that with my Teslas.

Yes, I have done this and it works. I've posted this suggestion in another thread, about the same topic.

One needs to get in the R1 and start driving. Maybe pressing the brake pedal would do?

G1 QT

 

[DB-EV]

Yes, I have done this and it works. I've posted this suggestion in another thread, about the same topic.

G1 QT

I thought that only worked if the vehicle was moving (ie it will say it is preconditioning but it only kicks in when it is moving)?

Prior to the update for Gen1, I found turning on the heat and heated surfaces AND charging at the same time, worked really well (that was the 240 mile trip where on EPA rating 270 I got equivalent of 282, stopping to charge about 200 miles in).

 

[R1TCntrlMaIzzy]

I thought that only worked if the vehicle was moving (ie it will say it is preconditioning but it only kicks in when it is moving)?

Prior to the update for Gen1, I found turning on the heat and heated surfaces AND charging at the same time, worked really well (that was the 240 mile trip where on EPA rating 270 I got equivalent of 282, stopping to charge about 200 miles in).

I edited my post, just before or at the same time you replied.

But, it will force the heating up of the motors and battery, and rather quickly. Well, in my case the L3 location is ~10 minutes away.

So, an on the move preconditioning. Some would say that is not preconditioning??

 

[sherold]

As we enter the winter season and the temps drop, I'm reminded again how range/efficiency drops in the cold weather.

I think I read somewhere that allowing us to manually precondition the battery is on the product roadmap. I know if the battery is warm it will be more efficient in cold weather and vice versa in hot weather. Any ideas as to how much more efficient? Does any one know what the ideal battery temp is? Hopefully Rivian can provide some guidance.

I've noticed usually around/above the 55°F and I get my normal expected efficiency. Below that and it drops until the batteries are warmer.

 

[sherold]

On Gen1 you can pre-heat using scheduling as heating the cabin also heats the battery. On Gen 2 however we are stuck until they release an update...which if I had to guess was planned for Fall 2024

Heating the cabin does not directly heat the battery packs and, is a horribly inefficient method of trying to precondition the batteries. Battery preconditioning uses current through the drive motor coils to generate heat, then uses the liquid cooling/heating loop to pump heated fluid through the battery packs. We do not currently have a way to explicitly activate this for preconditioning prior to a drive.

 

[R1TCntrlMaIzzy]

Heating the cabin does not directly heat the battery packs and, is a horribly inefficient method of trying to precondition the batteries. Battery preconditioning uses current through the drive motor coils to generate heat, then uses the liquid cooling/heating loop to pump heated fluid through the battery packs. We do not currently have a way to explicitly activate this for preconditioning prior to a drive.

It may not be the best method, but folks have posted that it works for them. They've done so by scheduling the climate in their G1 R1.

I suppose what's worse, this inefficient process or lower efficiency, regen in the cold weather? Pick your poison...

 

[zefram47]

Honestly, for wintertime driving your best bet is probably to just delay charging until it would finish shortly before your need to leave, assuming a predictable schedule. I really wish Rivian would add a charging for departure time option...my MINI Cooper SE had it and it was fantastic. The act of charging the battery also warms it...this morning I left with the battery at 69F just from charging and adding around 30 kWh at 24A (it charged from 12:30a until about 6:30a). Unfortunately, this means you need to know roughly how many kWh will be added and at what rate your charger will charge the vehicle. I usually use one of my trip meters as a since last charge gauge and just divide that by (in my case) 5.2 kW to get the number of hours required and then give a little buffer. But it's one more thing to remember to do vs Rivian just providing that so we can leave the charging schedule set to work with our various electric company ToU plans and not have to worry about it. During the summer when warming the battery isn't a concern, I leave the schedule much more open, mainly so it won't charge until I'm typically in for the night and I can just leave it plugged in.

 

[R1Thor]

TO BE CLEAR:
you're not cheating physics here.

You're using the same amount of electrons one way or another (with a smidgeon of fudge factor).

So, unless you REALLY need to eke out every last ounce of efficiency for long drives (maximizing your range), you're not benefitting by getting your battery warm so you can net 2.3 mi/kWh when you spent the equivalent amount of energy (charging/pre-conditioning/etc) to bridge the gap from 1.8 mi/kWh.

TL;DR: don't worry about it. You're chasing numbers, but expending the same amount of energy and money (or even more) to do it.

 

[sherold]

It may not be the best method, but folks have posted that it works for them. They've done so by scheduling the climate in their G1 R1.

I suppose what's worse, this inefficient process or lower efficiency, regen in the cold weather? Pick your poison...

Correct, and unfortunately we don't have the possibility to use the best available method on demand, which is the heating loop designed to heat the batteries. Anyone that has posted that using the cabin conditioning "works" for them to warm the batteries to any meaningful level is very misinformed.

It is not an effective method, at all. Using that method, the majority of the heat going into the batteries is due to use of the batteries to generate the cabin heat, not from heat soaking through the cabin floor, into segregated battery packs.

IF, and this is a big IF, the batteries are cold enough that climate preconditioning also activates the battery warming cycle through the BMS, this is an effective and intended method to heat the batteries. The vehicle is designed to heat the batteries this way. This only makes sense if you are using shore power to precondition prior to a drive though. unfortunately.

The inefficient process is worse. The amount of energy needed to heat the batteries up using this method is ludicrous. Wasting heat by heating cold air and surfaces that is not warming the batteries directly, in an attempt to warm the batteries to an efficient temperature, is going to consume much more battery overall than just driving with cold batteries.

 

[zefram47]

TO BE CLEAR:
you're not cheating physics here.

You're using the same amount of electrons one way or another (with a smidgeon of fudge factor).

So, unless you REALLY need to eke out every last ounce of efficiency for long drives (maximizing your range), you're not benefitting by getting your battery warm so you can net 2.3 mi/kWh when you spent the equivalent amount of energy (charging/pre-conditioning/etc) to bridge the gap from 1.8 mi/kWh.

TL;DR: don't worry about it. You're chasing numbers, but expending the same amount of energy and money (or even more) to do it.

Truth. But also, what I said just above your post about using the waste heat from charging to add some heat to the pack closer to your departure time.

 

[Riviot]

Battery preconditioning uses current through the drive motor coils to generate heat,

Exactly. Cabin precondition uses resistive heater and thermal leach to "warm" the battery.

Battery precondition is completely different and only works with the vehicle in motion, using resistance in the motors.

TO BE CLEAR:
you're not cheating physics here.

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