Battery Cooling for Summer

[smkettner]

Ok summer is coming and I have been scanning threads for how best to keep the battery cool.

Seems the battery cooling system operates when driving or left in ready mode. That is easy. Apparently the air conditioner may come on even if you have CC off and the windows down.

Active cooling also takes place if plugged in but I assume the RAV can be off. I assume the cooling will start as needed and draw power from the wall as needed. And RAV will do this even when not actively charging? Does the air conditioner compressor actually come on at some point?

And I assume if the RAV is turned off and parked in the sun all day it will just sit there and collect heat. Battery power will never be used in this situation to cool the battery.

Bare with me but my LEAF battery lost capacity too quick and I want to get this right from the beginning.

 

[TonyWilliams]

You are a good student!!! Fortunately, these are not NMC cells (Nissan LEAF / GM Volt / VW eGolf) and so far, not a single Rav4 EV has reported accelerated battery degradation.

If it's really hot, perhaps just use 120 volt charging to keep the cooling system powered and active.

 

[fooljoe]

Active cooling also takes place if plugged in but I assume the RAV can be off. I assume the cooling will start as needed and draw power from the wall as needed. And RAV will do this even when not actively charging? Does the air conditioner compressor actually come on at some point?

I don't think any cooling happens if you're not actively charging. Anyone seen otherwise?

 

[jspearman]

I would venture to guess that no one has a garage as hot as mine on the forum (often 110 degrees in mid-summer). I plug mine into a household socket as soon as it rolls into garage and supplement as necessary with the L2 charger i do this when the overnight temps reach 95-100 in the garage. So far I see no degradation after 1 summer and 16k mi, and the Leaf in the same garage fared very poorly the summer before, losing over 20% of capacity.

 

[smkettner]

I will be away for three weeks in the heat of Summer. Garage could easily get very warm 90+? Do I leave RAV plugged in or not?

 

[Kohler Controller]

I will be away for three weeks in the heat of Summer. Garage could easily get very warm 90+? Do I leave RAV plugged in or not?

Plug it in and use RAVCharge to activate climate control everyday at 1, 3, and 5 pm.

 

[TonyWilliams]

I will be away for three weeks in the heat of Summer. Garage could easily get very warm 90+? Do I leave RAV plugged in or not?

Plug it in and use RAVCharge to activate climate control everyday at 1, 3, and 5 pm.

Interesting. I never thought whether just cabin climate control would regulate battery temps. I doubt that it would.

The car has to be physically on, or charging. The 120 volt charge option should work well since on really hot days, it likely won't even keep up with cooling, and therefore not really add any charge.

If you're gone for 3 weeks in the heat, leave the battery at about 20%-30% and plugged in with a 120 volt / 12 amp charger on a timer that comes on every day between noon and 6pm (or whenever the latent ambient heat hits the battery).

You'll need an external timer so that you can stop the charge, too, every day. The issue with the car "sleeping" applies, and you'll need to wake it up with the proximity signal.

 

[fooljoe]

I've theorized that the "second charge" event that occurs from 20 minutes before your departure time to 7 minutes after is the battery getting thermally conditioned. If that's correct, and if this event happens even when you're already fully charged (big ifs), you could set numerous departure times throughout the hot part of the day. Or you could leave your keys in the car with a mechanical "finger" on a timer to turn the car on every afternoon (and of course a "foot" to depress the brake pedal so it goes in ready mode) then off later so it can charge back up. :lol: That might not even work though because the 'on' mode you get when it's still plugged in might not activate the TMS...

As you can see, there's not really any great answer here. I think the best move is doing whatever you can to keep your garage cool. Add one of these or maybe even a small air conditioner, and leave your car unplugged at around 50% charge. Maybe disconnect the 12v too, or put it on a tender.

 

[JasonA]

I thought the whole point of having an active TMS is the vehicle is ALWAYS watching over itself, the pack, etc. Why is it on the TMC forums you hear about these "phantom" power losses, owners waking up the next morning and going out into a warm/hot garage and there's a puddle of water coming from underneath the car?

I thought it actively kicks in and will cool for a bit if nec?

 

[TonyWilliams]

I thought the whole point of having an active TMS is the vehicle is ALWAYS watching over itself, the pack, etc. Why is it on the TMC forums you hear about these "phantom" power losses, owners waking up the next morning and going out into a warm/hot garage and there's a puddle of water coming from underneath the car?

I thought it actively kicks in and will cool for a bit if nec?

The Rav4 EV isn't that "active".

 

[miimura]

It would be interesting to "spy" on the car in very hot weather by putting CTs on the A/C power lines and some of the pumps with a monitoring system. I suspect that it will take quite a lot to get the A/C to kick on just for the benefit of the battery when the car is not in READY. Do we even know if the TMS and cabin conditioning loops are the same as Model S? People have posted some schematics and diagnostic screens for the the Model S at the TMC forum which are enlightening.

 

[JasonA]

The Rav4 EV isn't that "active".

 

[smkettner]

Is it better to charge during a hot afternoon before departing work.... or charging at home before departing in the morning?

Is there ever active cooling by the air conditioner when actually charging?

 

[Kohler Controller]

I will be away for three weeks in the heat of Summer. Garage could easily get very warm 90+? Do I leave RAV plugged in or not?

Plug it in and use RAVCharge to activate climate control everyday at 1, 3, and 5 pm.

Interesting. I never thought whether just cabin climate control would regulate battery temps. I doubt that it would.

The car has to be physically on, or charging.

Why wouldn't the car prepare the battery when the pre-climate feature is selected, especially if plugged into an EVSE in the garage? It gives it 15 minutes to prep the interior as well as the battery before the user arrives.

 

[TonyWilliams]

Plug it in and use RAVCharge to activate climate control everyday at 1, 3, and 5 pm.

Interesting. I never thought whether just cabin climate control would regulate battery temps. I doubt that it would.

The car has to be physically on, or charging.

Why wouldn't the car prepare the battery when the pre-climate feature is selected, especially if plugged into an EVSE in the garage? It gives it 15 minutes to prep the interior as well as the battery before the user arrives.

On second thought (I guess I already knew this), the car does consume 0.5kWh to precondition the battery from the timed departure.

 

[TonyWilliams]

Is it better to charge during a hot afternoon before departing work.... or charging at home before departing in the morning?

Is there ever active cooling by the air conditioner when actually charging?

Yes, when charging, the car is actually on, or for the 15 - 20 minutes prior to departure on the timed preconditioning, yes, the air conditioner will cool the battery.

Probably choice A; the hot afternoon, but if the battery is already hot, it doesn't just magically get cool. So, you'd be charging a hot battery until it cooled.

The trick is to not let the battery get hot.

 

[smkettner]

I may soon have 16a 240v at work to share with a few others.
I think I will opt for the afternoon shift. Probably charge the entire four hours..... especially if cooling draws off some power.

Thanks again for the info.

 

[ehelmholtz]

So does the Rav4 actively cool the battery if it is plugged in but the battery is full and not charging?

 

[Airton]

Like most EVs it does not. Best not to keep it fully charged (extended range charge 100%) for long periods of time in the heat.

 

[ehelmholtz]

This is unfortunate. The Volt's TMS is active when it's plugged in whether charging or not.

Anyway, it's been unusually hot in San Diego the last couple of days with temperatures where I am getting to 80-81 F so I left the car on while at work; I checked on it and after 7+ hours on, the range estimate went down by 3 miles.