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2021 RAV4 Prime XSE
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Discussion Starter #1
Hey R4P owners/gurus - I have read and heard lithium-ion batteries like to sit around at 40% state of charge. How concerned should I be about leaving it fully charged for a day or two? For example, I use the charge schedule feature to complete charging at 7a. If for some reason my plans change and I don't end up driving the car until the next day (or sometime over the next few days), should I leave it plugged in and simply drive it at next opportunity/need? I will certainly try to limit this scenario, but am I being overly cautious? I imagine Toyota knows that "life happens" and we owners won't always keep the vehicle in ideal conditions/state. I plan to have the vehicle as long as possible. Thanks!
 

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Hey R4P owners/gurus - I have read and heard lithium-ion batteries like to sit around at 40% state of charge. How concerned should I be about leaving it fully charged for a day or two? For example, I use the charge schedule feature to complete charging at 7a. If for some reason my plans change and I don't end up driving the car until the next day (or sometime over the next few days), should I leave it plugged in and simply drive it at next opportunity/need? I will certainly try to limit this scenario, but am I being overly cautious? I imagine Toyota knows that "life happens" and we owners won't always keep the vehicle in ideal conditions/state. I plan to have the vehicle as long as possible. Thanks!
I would like to know more about "lithium-ion batteries like to sit around at 40% state of charge," is there a link? Ty
 

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Discussion Starter #3
I would like to know more about "lithium-ion batteries like to sit around at 40% state of charge," is there a link? Ty
I should say that 40% was more of an average I have been seeing. Here's are a couple links for example - How to Make Your Lithium-Ion EV or Device Battery Last Longer - How Long Will My EV Battery Last? (and 3 Tips to Help it Last Longer) - it also says the following on pg 122 of the R4P owners manual, which seems to indicate the vehicle is not meant to stay fully charged for long - "Use the charging schedule function as much as possible in order to fully charge the hybrid battery (traction battery) immediately before starting off." Thanks!
 

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2021 Rav4 Prime max trim
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The vehicle is not meant to stay fully charge if it is going to sit for long time (2 - 3 months). Might as well let them read it themselves in this post;
 
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Discussion Starter #5
The vehicle is not meant to stay fully charge if it is going to sit for long time (2 - 3 months). Might as well let them read it themselves in this post;
Thanks Chazz - I did read that on pg 84, however if I'm reading it correctly, it seems that specific recommendation is to make sure the traction battery does not get too LOW if the vehicle is going to go unused for 2-3 months. Perhaps since there are no specific warnings/recommendations in the manual (that I can find) about leaving the vehicle at a HIGH state of charge for prolonged periods of time, I can take this as something I don't need to be overly concerned about? I have also seen posts on this forum, including yours, that indicate even when at "full charge" the SOC is actually around 90%, so that would seem to lessen the concern a little. Again, I imagine Toyota typically does what they can to make their vehicles "idiot proof", so to speak. Not that this scenario will occur often, but bottom line is, I'm looking for confirmation that leaving the vehicle plugged in and/or at full charge for a few/several days is not going to cause any significant issue to the longevity of the traction battery. Thanks!
 

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Thanks Chazz - I did read that on pg 84, however if I'm reading it correctly, it seems that specific recommendation is to make sure the traction battery does not get too LOW if the vehicle is going to go unused for 2-3 months. Perhaps since there are no specific warnings/recommendations in the manual (that I can find) about leaving the vehicle at a HIGH state of charge for prolonged periods of time, I can take this as something I don't need to be overly concerned about? I have also seen posts on this forum, including yours, that indicate even when at "full charge" the SOC is actually around 90%, so that would seem to lessen the concern a little. Again, I imagine Toyota typically does what they can to make their vehicles "idiot proof", so to speak. Not that this scenario will occur often, but bottom line is, I'm looking for confirmation that leaving the vehicle plugged in and/or at full charge for a few/several days is not going to cause any significant issue to the longevity of the traction battery. Thanks!
Not only is it safe to leave it plugged in for several days, it will keep your 12V battery maintained. We have owned Toyota PHEV's for 8 years now and never had traction battery, or for that matter 12V battery issues. Toyota engineers their HSD system for longevity and minimal degradation.
 

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Lithium batteries are lithium batteries. Higher charges for longer times or very low charges worsen longevity. In a perfect world, we would charge to 60% and discharge to 40% and then recharge again. Obviously that isn't functional, though. Do what you want, but I set my departure time on my Prime to say that I am leaving at about 11:30am, even though I usually leave around 7:30am. I'm only using a normal slow charging outlet so I still have about 90% available charge when I unplug. My average kwh mileage is 3.1 so even with a ~90% charge I have a range of about 40 miles. My commute is about 21 miles round trip so that is more than enough for me. On a full charge, when I have done it a couple times, was 49 or 50 miles estimated but driving habits affect that.
 

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Try to avoid letting the car sit at a full charge, however doing it every once in a while isn't going to reverse all your hard work. All batteries age, for every "bad battery behavior" you perform, you're just aging it a little quicker, the more often you do it, the quicker it ages. Don't let the anxiety tear you apart though.

Side note: High temperatures are really harsh on batteries, the higher the temperature, the more it ages a battery. If you can park your car in the shade on a hot summer day vs out in the sun, you'll make more inroads at preserving battery capacity than worrying about how full of the charge the vehicle gets.
 

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Discussion Starter #9
Try to avoid letting the car sit at a full charge, however doing it every once in a while isn't going to reverse all your hard work. All batteries age, for every "bad batter behavior" you perform, you're just aging it a little quicker, the more often you do it, the quicker it ages. Don't let the anxiety tear you apart though.

Side note: High temperatures are really harsh on batteries, the higher the temperature, the more it ages a battery. If you can park your car in the shade on a hot summer day vs out in the sun, you'll make more inroads at preserving battery capacity than worrying about how full of the charge the vehicle gets.
Thanks for the info - good news here is I'm in Upstate NY, where hot weather certainly doesn't dominate the year. LOL I imagine cold weather (we of course get lots of that) isn't kind to batteries either, but I've read it's not as destructive as heat.
 

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The Rav4 Prime's actual SOC when fully charged should be less than 100% of the battery pack if it's similar to the Prius Prime. You can confirm this with an ODB2 reader. They keep this limit for longevity, as it keeps the battery from being 100% charge. But also, over time, as the battery pack loses its capacity, you don't see this in your every day driving since the software starts to decrease this 16% buffer -- actually, that part I'm not sure on, but I think other EV manufacturer's do this. Here's a good video on it:

 

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No going to worry nor change how I am driving or changing. Have people considered that the same general thing has been happening with our ICE vehicles? AAA reports the best mileage for them is typically at 15,000 miles and then thereafter due to rings wearing, berating begrading, etc, that they are thereafter losing MPG the longer they are driven.
 
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