Battery Pre-Conditioning

[KarlC]

Setting Battery Pre-Conditioning vs Just Charging 30 mins before departure

The below post looks like Just Charging 30 mins before departure is the way to go as charging warms up the battery.

This sounds like it would work well in So Ca where Im at, but maybe not in some of the really cold states ??

Just something I came across through trial and error, because I too have an undefined departure schedule, daily.

So I generally leave the pack to charge to about 90% full, and then EVSE cuts off. But before departure I go in via the app and start charging again. Typically I'll do this about 30-40 minutes prior to departure, and I've noticed pretty much the same range doing it this way, rather than setting a preconditioning timer. It also saves electricity, because you're using electricity to both fill the pack, and warm it (charging batteries warms them up significantly). For more data points, I've noticed the car still pulls 6+kW until about 94-95% then tapers down to 2.5-4kW until 100% full. When I used to do the precon, i believe it pulled about 2kW from the mains to heat the battery. I'd rather put that 2kW into the pack and heat it at the same time. Give it a try.

 

[Fisher99]

Yes, I have tried that approach and it does work to a reasonable degree. However, since my EVSE doesn't have the ability to stop charging at a specified percentage, it is a manual process for me. Which means that more often than not I forget to keep tabs on the charging and end up with a full charge rather than shutting it off at 80-90%.

 

[electronchaser]

Setting Battery Pre-Conditioning vs Just Charging 30 mins before departure

The below post looks like Just Charging 30 mins before departure is the way to go as charging warms up the battery.

This sounds like it would work well in So Ca where Im at, but maybe not in some of the really cold states ??

Just something I came across through trial and error, because I too have an undefined departure schedule, daily.

So I generally leave the pack to charge to about 90% full, and then EVSE cuts off. But before departure I go in via the app and start charging again. Typically I'll do this about 30-40 minutes prior to departure, and I've noticed pretty much the same range doing it this way, rather than setting a preconditioning timer. It also saves electricity, because you're using electricity to both fill the pack, and warm it (charging batteries warms them up significantly). For more data points, I've noticed the car still pulls 6+kW until about 94-95% then tapers down to 2.5-4kW until 100% full. When I used to do the precon, i believe it pulled about 2kW from the mains to heat the battery. I'd rather put that 2kW into the pack and heat it at the same time. Give it a try.

This is exactly where it's used. Works great with battery temps around 24-27 C at departure time, when I have time to check it. ...even in 40-50 F socal winter months.

What I love more is how toasty dcfc makes the battery. nice 30c. I dunno, it's prob in my head, but I perceive better performance for a short while after dcfc. I imagined heating everything up helps them electrons flow just a smidgen closer to the speed of light.

 

[symonray]

With my JuiceBox Pro 40, I try to get the benefit of both (battery preconditioning and heat from the charging process) during the winter months. I schedule the charging time to start around 3 hours before my departure time (set through the ConnectedDrive app) and also adjust the Amp settings on my charger so that the pre-set charging limit level (usually around 85-88%) is reached within 5 to 15 minutes of my departure time. That routine seems to really help my range on my morning commute. Unfortunately, since I have no chargers available during the day near my workplace to repeat the process, my battery range on the evening commute is less due to the battery being cold.

 

[eNate]

This is very interesting. I'll have to begin checking my battery temperature when leaving work at 11PM.

I imagine charging at 120v / 16A doesn't do a whole lot to warm my battery over the course of the afternoon and evening.

While I recoup about 5% SOC per hour during the early part of my work day (according to the Connected Drive app), that gain is substantially reduced during the final three hours.

On the rare instance my app says the cars has reached 100% before quitting time, I find myself at 97% or 98% when I get to the car. That makes sense.

But to throw a wrench in my theory, I turned off preconditioning for a few cold nights, and observed two things: It did NOT maintain that 5% SOC accumulation during the final hours, and my drive home resulted in about the same battery usage as on nights I preconditioned.

 

[eNate]

I imagine charging at 120v / 16A doesn't do a whole lot to warm my battery over the course of the afternoon and evening.

WOW!

In answer to my own question, I've been charging at 120v / 16A all day, from 7:30 to 3:00, with the battery just reaching 98%.

My battery temperature is a meager 57° F (14°C) according to the hidden menu.

Outside temp, according to the car, is 58°F (14.8° C).

But coolant temperature is showing 118° C. Does that make sense? 244° F? Does the coolant also cool the charger itself?

 

[alohart]

But coolant temperature is showing 118° C. Does that make sense? 244° F? Does the coolant also cool the charger itself?

Every time I've looked at coolant temperature, it has been 118º C even after our i3 has been parked for several days with the ambient air temperature in the high 70º's. So the coolant temperature reading must be bogus for some reason.

 

[eNate]

Oh, wow, I'll have to lol into that.

Same tonight after driving for an hour... Coolant 128° C, though battery temp raised to 17° C / 62° F by end-of-trip. Not much, but greater than the low 50's outside.