Rav4 Lower Charge Rates?

I have some questions about charge rates and it effects on battery health, longevity, and range. If this has been covered someplace else then please let me know.

I am interested in all aspects of charge rate on the Rav4 batteries, but specially at this time in charging at a Lower Rate. My understanding is that traditionally there are advantages to charging strings of batteries at a lower rate. In any group of cells there will be variations in the cells - capacity, internal resistance etc. And that the faster you charge the more pronounced the variations become.

80% or more of my charging happens over night when there is no rush and I have a Juicebox that allows me to adjust the charge rate.

Admittedly I know very little about the BMS in the Rav4/Tesla battery.

So some questions

1) Would charging at lower rates allow the cells to charge more evenly?

2) Would it potentially reduce heat buildup, I live in TX.

3) Would it possibly extend the longevity of the battery?

4) Could it allow a higher percentage of the cells to reach optimum capacity absorbing more energy?

4) What would be the disadvantage, if any, of charging the batteries at a lower rate?

5) What would be an optimal rate?

I am sure there are other questions, these are just things that have been on my mind.


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I don't think there is any real benefit to charging slower than 240V 30A. In fact, you will waste more power charging slower because the RAV continuously runs the coolant circulation pump(s). That fixed wattage consumption will accumulate more kWh the longer you stretch out the active charging.

If you could log the Tesla CANbus, I'm sure you could collect something useful that would answer your questions in more detail, especially about the temperatures and distributions of cell voltages.

I currently own a Focus EV with the 23Kw battery and am completing purchase of a Rav4 EV this weekend.

30 Amps or 7.2Kw into the 41Kw Battery would be roughly C/6 where 40 Amps 9.6Kw would be closer to C/4?

Most of the manufacture info about charging Li-on single cells( not a string) focuses on how quickly the cells can be charged and indicate C/2 - 1C. But that's a single cell and the emphasis is always on getting the batteries charged as quickly as possible - apposed to cycles and battery longevity.

I was not aware the Rav ran the cooling pump the entire time so thanks. I was also thinking that running the charger at too low of a rate would simply accrue additional hours of run time for the charger.

When I charge the Focus EV at 7Kw or roughly C/3 you hear the battery cooling system kick in after a while. However if I charge below C/5 or 4- 5Kw it does not. Again this is Houston Tx so take that into account.

I have a Vectrix(diff battery chemistry) and their chargers tended to kill the packs due to high charge rates and heat in warmer climates.

For that an other reasons I have made a point not to charge my FFE at 100% when there is no rush. Thinking something below C/5 or 75% of the charging system capacity may add to the longevity of battery and charging components.

I am just curious if going lower may have advantages. Either consistently or as an equalization process.

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toddh said:

Most of the manufacture info about charging Li-on single cells( not a string) focuses on how quickly the cells can be charged and indicate C/2 - 1C. But that's a single cell and the emphasis is always on getting the batteries charged as quickly as possible - apposed to cycles and battery longevity.
I was not aware the Rav ran the cooling pump the entire time so thanks. I was also thinking that running the charger at too low of a rate would simply accrue additional hours of run time for the charger.
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Click to expand...

Given that one person here recently posted that he put 96k miles on his rav4ev, charging extended (100%) mode twice a day and only measured 15% battery losses .
I think you gain much more by not getting below the 20% charge level for longevity.
Same goes for your phone/pad/laptop btw ;-)

Focusing on minuscule differences in charge rate is a waste of time.

As we learned from the Nissan LEAF, don't let the cells get too hot.

If it is exceptionally hot outside, and your car is parked, there's no harm in leaving the car on all day. You can lock the door with the mechanical key that is located in the fob, however make sure you take both the fob and key with you after you lock the door. The RAV4 EV will chirp three times as you walk away to let you know that you left the car on.

I recommend turning the lights off, and also turning the center navigation screen to off by holding the lower button for three seconds. You can also turn down the instrument lights. When you return to your vehicle it will be nice and cozy because you would've left the air conditioner on !

Alternately, you could leave the car plugged in all day provided it was actually charging. This will operate the cooling pumps also.

None of the cooling system works of the vehicle off. Charging the vehicle is by far the best way to keep the battery cool.