Maximizing battery health - Heat and State of Charge

Another option is to just drive your car and enjoy it, plugging in whenever you are able and trusting the engineers who put this car together with the battery management system will know more about whats best than you or I ever will.

 

Even driving my wife's plug-in Pacifica, I noticed on a day like yesterday when the temperatures were 103°, the battery coolant will get up to 110°. But charging in the morning (coolant fans come on) , with the programming set for departure time, the traction pack will be cooled down to 75° - as the morning outside temperature is around 68°.
Just observations, on a liquid cooled plugin. With fans/air cooled - YMMV.
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GASP.
What a novel idea.
Which flies in the face of everything OCD !!

 

Leaving a full battery in the hot sun is not good for the battery long term. Since you can't control the weather, I would use the charge timer (with climate prep on) at home and at work. This way the battery is at full charge for only a short while.

 

If there's easily done measures that could improve the battery's life, I'm all for it, I mean: why not?

 

I think it is worse to leave a full battery sitting in the hot sun all day than to charge when it is hot out. If you have access to your car before the charging starts when it is hot out, just turn it on then off and the battery cooler message will show up. I don't know how much heat charging generates, some more knowledgeable members may be able to help with that.

 

are you tinted to the legal maximum, and using solar window shades?

 

It's really the Shaded asphalt you're sitting on. That can mean and easy 35° difference.
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Option 2 for both. Charge the battery just before you want to use the capacity you put in it.

Commute side - if the car is hot, the A/C will run as necessary, powered from external power. The battery will be protected.

Home side - charge just before you need the power.

 

Charging the battery when it is REAL HOT probably is not good for it.
You might want to limit your charging at work to the first couple of hours after you arrive.

In the end, no matter what you do it is not likely to have any significant impact on the life of your battery.

Are hybrid owners more prone to OCD than the population in general ? Sure seems like it.

 

heat from charging is a ratio how many KW's are going in, & the traction pack size. Since the prime only charges ~ 3½kW's - the incoming current isn't going to have a critical amount of heat added, but still, you wouldn't want to do that on 100° day sitting on hot black asphalt.
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And on L1 it is a lot less.

 

Yep - 2hrs L2 or 6hrs L1.
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Here's what the Prime owner manual has to say about capacity reduction in the traction battery.

The capacity of the hybrid battery (traction battery) will decline gradually when the hybrid battery (traction battery) is in use. The rate at which it declines will differ in accordance with environmental conditions and the way in which the vehicle is used. Observing the following can help suppress battery capacity decline.

●Avoid parking the vehicle in areas with a high temperature under direct sunlight when the hybrid battery (traction battery) is fully charged.
●Avoid accelerating and decelerating frequently and suddenly when EV driving.
●Avoid frequent driving near the top speed for EV driving.
●Leave a low level of charge in the hybrid battery (traction battery) when leaving the vehicle undriven for a long period of time. After confirming that EV mode has switched to HV mode, turn the power switch off.
●Use the charging timer function as much as possible in order to fully charge the hybrid battery (traction battery) immediately before starting off.
​

From this we would conclude that it is not preferable to charge the battery on arrival to work and leave it in the hot sun the rest of the day with a full charge (1st and last paragraphs). Better to charge just prior to leaving to drive home. If the car is hot and the battery needs cooling, the HVAC system will provide it during charging. If you charge earlier in the day, there will be no cooling for the hot battery the rest of the day.

For the same reason, at home use the charge timer and charge the battery just prior to leaving to drive to work.

If this were the case, Toyota probably would have omitted that section of the owner manual.

The car will run its HVAC system as required to cool the traction battery during charging. The subsequent paragraphs of the manual note that if it is very hot or very cold when charging, the battery will not charge fully to protect itself:

When the remaining charge of the hybrid battery (traction battery) is low after charging

In the following situations, the remaining charge of the hybrid battery (traction battery) after charging completes may be less than normal in order to protect the system (the EV driving range after the battery is fully charged may be shorter).*

●Charging is carried out when the outside temperature is low or high

●Charging is carried out immediately after high-load driving or in extreme heat​

If you charge in the afternoon and the car is not fully charged (and you don't suspect the problem you were having with the L2 charger), then it is likely that the termperature was too high for the battery to fully charge. You may also see this message on the MID:



You will also want to ensure the charging equipment cooling air intake vents under the rear seats are not blocked and are kept clean.

 

And my opinion is: If any of that really made any SIGNIFICANT difference to the longevity of the battery, they probably would have included a guestimate as to how much.

What they are quoting is an engineers view of battery parameters.
They, no doubt, put that same wording in the very first hybrid manual......without any real world data to know if it was going to be a factor or not. They may still not have any.