I have the same issue some weeks. In terms of battery longevity I believe it is best to charge less frequently rather than more. That being said you might not want to run the battery down to zero each time, but recharge with a few miles left. Considering the safeguards Toyota has built in to maintain battery longevity it might make no difference at all.

 

I would charge when it says 20 miles remaining, and charge to about 35. Or 15 - 40 maybe. Basically staying away from both extremes.

 

Maybe set the timer to start charging an hour before departure every day? That would get you 3-4 miles. As others posted keep around 20 miles in the battery? You do not want to keep it fully charged. Skip a day when the level creeps up?

 

I have owned our first Prime now for almost 13 months and I charge twice a day Monday - Thursday and twice Friday -Sunday when the battery is down to between 15 and 8 miles remaining and so far range has been consistent between 44 and 46 miles DTE.

 

Honestly if you’re that close why not just walk to work? Being that close is a blessing!

 

If it was my work I would (I did so in fact about 10 years ago when my work was 3 miles away.) But my wife teaches Kindergarten and has to carry a ton of stuff back and forth every day.
If they put in a walking path to the school she still may consider it but even though it is only a stone's throw away there is a wetland in between and as of yet they are not planning to make the direct route accessible (new school). That means it would be a 1 mile walk partly along a busy street with no sidewalks and we live in the PNW where it rains a lot.
Good thought but at this point not a practical option if there is a working car in the driveway.

 

That makes sense. EV mode it is then!

 

Li batteries generally last longest when used in the middle of their charge range. If you could keep the charge between 20% and 80% of full charge that would be great. How to do that without creating lots of headaches isn't always easy but if you use an EVSE that allows charging for X kWh or X minutes then that should help a lot.

 

Battery wont never be total full or empty. Toyota has 10 year and for Us in Finland 350 000 km varranty. Maybe they have pmanner allready what is the best for the battery. 1 year soon driven and I keep the charger cable allways connected when Im at home. 2 months EV was 95 shown on meter and now it has dropped under that, couse weather is getting colder.

 

I have seen multiple references to charging the vehicle right before you use it but I must have missed the why. Lithium is supposed to hold charge well so it can't be that. My cordless tools and such say it is better to let them cool off a bit before using them (or is it cool off before charging them?). Only other reason I can think of is I read that having the charge cord connected puts some drain on the 12V so you don't want to leave it on the charger for too long - but I thought that meant days not hours. OK I am stumped - why should you charge right before you plan to use the car?

 

I think it's to avoid the car sitting with a full charge as this is supposed to be bad for the battery.

I think people are going way overboard with micro managing the SOC.

 

OK - So I think I am hearing two things:
1. These are marginal lifecycle issues - Toyota has safeguards in place to make sure they aren't paying out big warrantee claims and it is not like the first rechargeable batteries that had a memory set if you didn't manage the charge cycle carefully.
2. The reason for charging right before driving is to limit the length of time the battery sits with a relatively high charge. If I only charge it 60-70% that shouldn't matter.
Did I get that right?

One other charge issue I have seen in rechargeable battery devices is to avoid many small charges. But I am thinking that is what the regenerative braking is doing all the time you are driving in the city so recharging for short durations via plug-in should not be an issue. Does that make sense?

 

OK - So I think I am hearing two things:
1. These are marginal lifecycle issues - Toyota has safeguards in place to make sure they aren't paying out big warrantee claims and it is not like the first rechargeable batteries that had a memory set if you didn't manage the charge cycle carefully.
2. The reason for charging right before driving is to limit the length of time the battery sits with a relatively high charge. If I only charge it 60-70% that shouldn't matter.
Did I get that right?

Sounds reasonable.

One other charge issue I have seen in rechargeable battery devices is to avoid many small charges. But I am thinking that is what the regenerative braking is doing all the time you are driving in the city so recharging for short durations via plug-in should not be an issue. Does that make sense?

See your number 1).
How do you think Toyota hybrids managed all these years? Lots of short charging-discharging cycles and still managed to last 200k+ miles.

 

Few things to add because I see a lot of bad assumptions being made here.

Toyota warranties the batteries, but does NOT warranty range degradation, so you should manage how you treat your battery if you want the range to last a long time.

Toyota currently caps the highest and lowest a battery charge will go, to help you with this already(I think it's around 15-90% currently). However, the other reason they do this is because as the battery does lose capacity, you can actually just allow the car to charge to a higher or lower %, and still give the customer the same range (so maybe in a year or two, the car charges from 12%-93%, etc.). Every EV is designed this way. So for the first few years (like RussC pointed out), you won't notice any change, but after some point (whether that's 3-8 years out, it just depends how you treat it), you will start to notice the degradation. Degradation will show up two ways, reduced capacity, and reduced peak output. These cars at some point won't be doing 5.7s 0-60, when that is, is entirely dependent on how well toyota designed the battery management system, battery chemistry, and how you treat it. Only one of those variables is under your control.

Many EV makers put Capacity meters in their infotainment systems so you can see how much a battery has degraded overtime, this helps when it comes to resale because it's a lot like pointing out how many miles are on an engine, right? For some reason, Toyota didn't put one on this car, maybe it's accessible via OBD2, but I haven't heard anyone with any luck accessing it. Because of that, we can only speculate on what behavior may or may not be impacting battery degradation.

 

update on charging plan and question about degradation:

I charge the battery to 25-35 miles EV range and we drive on that single charge during the week. If we have driving plans over the weekend I charge to a fairly high state right before we leave.

Based on what I have seen I expect the batteries to degrade over time. But since the R4P is a PHEV it has a lot of excess charge capacity over the pure hybrid design and I would expect that the vehicle should be usable as a practical HV long after a pure hybrid requires new batteries. Replacing the batteries would certainly be desirable to enable a reasonable EV range (and we all hope battery costs will come down by then) but I would think driving would remain practical even after substantial battery degradation unless an associated voltage drop causes other issues. Can anybody confirm this or explain if it is incorrect? I am an engineer but all my electrical education accomplished was to reduce my Physics grades.

 

I have zero worries about the battery ever degrading so much the HV system doesn't work. As for EV range, I'd say it's too early to tell since there are no Primes that have been driven for > 5 years. I have some experience with a Nissan Leaf and on that car, time more than mileage seems to be the main factor in battery degradation (and high temperatures on early models). On the Leaf, the batteries have gotten better every year. Not surprising for a new technology like EVs. The Nissan Leaf battery has absolutely no temperature control, except the car will throttle back charging if the battery is too hot.

Since the R4P has at least some battery cooling, and it is a newer model vehicle, I'd expect the batteries in it to perform as good or better than the latest Leafs' batteries. The latest Leaf generation started in the 2018 model year and there are some very knowledgeable users in places like Phoenix, AZ (heat is hard on Li batteries) and they report <10% degradation after 4 years with up to 50k miles, etc. Compared to earlier Leaf's this is much better. The very first Leaf's had terrible batteries and some of them have lost 50% capacity in 10 years. Starting in 2013, the batteries were improved and some of them are still at 80+% capacity after 8 years.

To extrapolate based on another company's products, I'd expect the R4P EV batery to still have 80+% of its original range after 10 years but we'll know for sure in about 7 years.

 

I have zero worries about the battery ever degrading so much the HV system doesn't work. As for EV range, I'd say it's too early to tell since there are no Primes that have been driven for > 5 years. I have some experience with a Nissan Leaf and on that car, time more than mileage seems to be the main factor in battery degradation (and high temperatures on early models). On the Leaf, the batteries have gotten better every year. Not surprising for a new technology like EVs. The Nissan Leaf battery has absolutely no temperature control, except the car will throttle back charging if the battery is too hot.

Since the R4P has at least some battery cooling, and it is a newer model vehicle, I'd expect the batteries in it to perform as good or better than the latest Leafs' batteries. The latest Leaf generation started in the 2018 model year and there are some very knowledgeable users in places like Phoenix, AZ (heat is hard on Li batteries) and they report <10% degradation after 4 years with up to 50k miles, etc. Compared to earlier Leaf's this is much better. The very first Leaf's had terrible batteries and some of them have lost 50% capacity in 10 years. Starting in 2013, the batteries were improved and some of them are still at 80+% capacity after 8 years.

To extrapolate based on another company's products, I'd expect the R4P EV batery to still have 80+% of its original range after 10 years but we'll know for sure in about 7 years.

My parents and brother have both owned Leafs in phoenix against my advice. Try 10% degradation in about a year and a half. My parents have already had their 2017's battery replaced under warranty. My brother sold his 2013's with 60% capacity last year. The 2011's and 2012's were even twice as bad here in the phoenix area. I think some of them ended up with 50% capacity after only 2-3 years.

In terms of battery management, I think the leaf is probably the worst designed EV, it's also one of the cheapest (go figure).

 

Thanks for the info. I am not "worried" about battery degradation but I tend to keep my cars awhile (just sold 1988 Ranger and 2009 Kia and still drive 2002 Odyssey) so I want to understand whether my theory that the extra capacity of a PHEV should provide practical longevity well beyond the warrantee holds water or not.

 

C-rate (current/capacity) does matter for battery longevity. All other things being equal, higher C-rate charging or discharging reduce the battery's lifespan compared to lower C-rates. So in this case a larger battery would increase longevity although the R4P is much heavier than a Prius Prime so it may be a wash.

I have an SE and I consider the 3.3kW charger to be very easy on the battery. When in EV mode I'm light on the pedal when possible since that also reduces the C-rate. How much does this matter? Probably not enough to even notice over the life of the car but I also keep my cars for a long time and try to do everything reasonable to keep them in good shape.

 

The volts have been around almost 10 years now, and I don't believe they have degraded significantly at all. As of about a year or two ago, I didn't notice any complaints from owners in phoenix (which would be a great worst case test case) about significantly degraded batteries. The volt uses a similar cooling system as the R4P, and the battery tech is much older.

That's probably a good sign for the R4P. As this car uses Depth of discharge control, and can effectively hide some degree of battery degradation over a stretch of time, I'd expect it to be at least 5-10 years before even a minor decrease could be noticeable. And that's if you treat the battery like crap (leave it fully charged at all times, floor it every opportunity you have, leave it parked out in the phoenix sun all day long for months on end, etc.)

Like previously mentioned, this car works great even as a hybrid. Say you can't push it up to 84 mph anymore, or it only can go 30 miles on all EV, it would still be valuable to another buyer. a pure BEV on the other hand.....

 

I was concerned about getting the most out of my battery. I found out the the software only charges it to 80%, even thought it reads 100%. Also it will not allow the battery to deplete itself just the same. They would be changing lots of batteries over the 10 years of warranty. I told my wife, just to plug it in when it hits 0 miles. Besides, its good to run the engine a little just as well, when it switches to HV.

 

In the R4P Owner’s manuals (OM) I found references to “2 or 3 months” in context of storing for “a long period of time”. In the R4Prime OM it looks like they are recommending turning on the ICE every 2 to 3 months in case the traction battery needs charging (below %14.7 SOC usually triggers HV mode). So then “a long period of time” would be more than 4 to 6 months.

And then under the heading (on prev page) Capacity reduction of the hybrid battery (traction battery), we have the advice to leave “low” charge/capacity on the traction battery if left un-driven for a long period of time. Now we just have to guess what “low” charge means exactly (% SOC).

I never use the charging schedule function to finish charging closest to departure time.

 

In the R4P Owner’s manuals (OM) I found references to “2 or 3 months” in context of storing for “a long period of time”. In the R4Prime OM it looks like they are recommending turning on the ICE every 2 to 3 months in case the traction battery needs charging (below %14.7 SOC usually triggers HV mode). So then “a long period of time” would be more than 4 to 6 months.
View attachment 172889


And then under the heading (on prev page) Capacity reduction of the hybrid battery (traction battery), we have the advice to leave “low” charge/capacity on the traction battery if left un-driven for a long period of time. Now we just have to guess what “low” charge means exactly (% SOC).
View attachment 172890
I never use the charging schedule function to finish charging closest to departure time.

In the R4P Owner’s manuals (OM) I found references to “2 or 3 months” in context of storing for “a long period of time”. In the R4Prime OM it looks like they are recommending turning on the ICE every 2 to 3 months in case the traction battery needs charging (below %14.7 SOC usually triggers HV mode). So then “a long period of time” would be more than 4 to 6 months.
View attachment 172889


And then under the heading (on prev page) Capacity reduction of the hybrid battery (traction battery), we have the advice to leave “low” charge/capacity on the traction battery if left un-driven for a long period of time. Now we just have to guess what “low” charge means exactly (% SOC).
View attachment 172890
I never use the charging schedule function to finish charging closest to departure time.

Why not? Seems antithetical? We too have had 7 Toyota Hybrids without a traction battery issue and have used the charging schedule on the PIP, PP and R4Ps, to finish at 6am just prior to use. It's worked very well for us where is the empirical data to disprove it?

 

Here is one source of lots of information about various battery chemistries: Battery University - Prolonging Lithium Batteries

The link above is to just one page of dozens at the site which are worth exploring.

I’m a new RAV4 Prime owner, and I’m also a long time user of lithium-based rechargeable batteries in radio controlled aircraft and drones where considerable attention is paid to battery capacity and longevity. Based on my experience in that context, we generally charge cells to their “true” 100% SOC (for maximum flight time), and try to avoid storing them in that state for more than a week or so (to minimize battery degradation). If we don’t fly within about a week then ideally we discharge cells to about 50% SOC for longer term storage. Many modern drones include smart battery management circuits that automatically do a partial discharge after a set number of days, typically 7-10 days.

Having said that, and also having driven my previous vehicle (a 2012 Camry Hybrid) for 155,000 miles with no perceptible battery degradation - and knowing that these vehicles intentionally limit charge and discharge such that both full (“true” 100% SOC) charge and discharge aren’t possible, I’m choosing to charge my Prime nightly (with an L2 charger @16A which yields a rate of about 10mph, and perhaps is just a little less stressful on the cells and the temperature management systems in the Prime) whenever it’s been driven during the day, regardless of the SOC. I also top off the traction battery whenever I return home during the day (@32A or ~20mph, which may be a bit more stressful, but gets the job done faster!) if there’s any chance that I’ll drive additional miles later in the day. This approach minimizes use of the ICE. (I’m hoping to drive 1,500-2,000 miles or more between visits to the gas pump.) I believe that the design of integrated battery management systems will likely have a far greater impact on overall battery life and performance than our personal charging habits.

Of course, I won’t know the consequences of my approach anytime soon…

 

Here is one source of lots of information about various battery chemistries: Battery University - Prolonging Lithium Batteries

The link above is to just one page of dozens at the site which are worth exploring.

I’m a new RAV4 Prime owner, and I’m also a long time user of lithium-based rechargeable batteries in radio controlled aircraft and drones where considerable attention is paid to battery capacity and longevity. Based on my experience in that context, we generally charge cells to their “true” 100% SOC (for maximum flight time), and try to avoid storing them in that state for more than a week or so (to minimize battery degradation). If we don’t fly within about a week then ideally we discharge cells to about 50% SOC for longer term storage. Many modern drones include smart battery management circuits that automatically do a partial discharge after a set number of days, typically 7-10 days.

Having said that, and also having driven my previous vehicle (a 2012 Camry Hybrid) for 155,000 miles with no perceptible battery degradation - and knowing that these vehicles intentionally limit charge and discharge such that both full (“true” 100% SOC) charge and discharge aren’t possible, I’m choosing to charge my Prime nightly (with an L2 charger @16A which yields a rate of about 10mph, and perhaps is just a little less stressful on the cells and the temperature management systems in the Prime) whenever it’s been driven during the day, regardless of the SOC. I also top off the traction battery whenever I return home during the day (@32A or ~20mph, which may be a bit more stressful, but gets the job done faster!) if there’s any chance that I’ll drive additional miles later in the day. This approach minimizes use of the ICE. (I’m hoping to drive 1,500-2,000 miles or more between visits to the gas pump.) I believe that the design of integrated battery management systems will likely have a far greater impact on overall battery life and performance than our personal charging habits.

Of course, I won’t know the consequences of my approach anytime soon…

yup kind of agree the system should take care of itself pretty good . now anything i can do to help witch doesnt put me out ill do . eg get home and go to charge ill set it to finish charging at 0800 am . no big deal im right there .the one thing i will do that will put me out a bit is checking and cleaning/replacing battery air filters on the regular this i believe will do more than anything in promoting battery life and efficiency.

one caution spoke to a Toyota meck on this subject and he has seen very little issues with phev battery's (prius} but he stressed immediately engine issues with ev supper milers mostly city people not using the ice . he suspects with the range of the rave 4 prime he will eventually see more of this .

 

I agree “shorter time period between finished charging and consuming the electrons would be a net positive…”.
It’s just not net positive enough to change my habits.

I had something in mind when I wrote your bolded quote, but I never finished or conveyed it very well. I deserved a challenge to that statement, and I feel better now I have expressed more of my mindset. Thanks.

The experiment continues for now.