Toyota RAV4 Forums banner
Cancel
Create thread New Garage Forums

Charging information regarding the Hybrid Battery

Jump to Latest
1 - 19 of 19 Posts

paid4c4

· Registered
Joined
·
191 Posts
Discussion starter · #1 ·
I took delivery on January 3rd of our new 2020 Rav4 Limited Hybrid. I've been watching the power screen to get an idea how the power transfers between engine, motors and battery. I have two questions; 1-Does it take some time for a new hybrid battery to get fully charged. 2-Does the hybrid battery ever get completely charged so the charge meter is full? I'm at about 34 MPG and working on improving my driving skills. Probably not going to get much better mileage until warm weather.
Bill
 
#2 ·
Under normal driving conditions you shouldn't expect the battery to ever be fully charged. One of the main ways that a hybrid improves fuel economy is by regenerative braking, but if the battery is completely topped off there's no place to store that energy so it's just lost. About the only time you might expect the battery to completely charge up is when coming down from a mountain pass (at which point you might consider engine braking).

The two best things I've found to improve fuel economy are 1) be light on the accelerator and 2) keep the heat low in the winter.
 
#3 ·
paid4c4 said:
I took delivery on January 3rd of our new 2020 Rav4 Limited Hybrid. I've been watching the power screen to get an idea how the power transfers between engine, motors and battery. I have two questions; 1-Does it take some time for a new hybrid battery to get fully charged. 2-Does the hybrid battery ever get completely charged so the charge meter is full? I'm at about 34 MPG and working on improving my driving skills. Probably not going to get much better mileage until warm weather.
Bill
Click to expand...
Normal operating range for the battery display is 2 bars to 6 bars. (8 total) As a rule you should normally see it between 4 and 6 bars. You'll only see 7-8 bars after long downhill stretches.
 
#4 ·
I’ve only ever gotten mine to 8 bars when driving from 5000 feet elevation to 1000 feet. Lots of recaptured energy while driving downhill. The rest of the time you’ll almost never see it at 8 bars and more likely is 3-7 bars. Normal.
 
#6 ·
camfused said:
I read somewhere that Toyota purposely keeps them between something like 30%-80%, to enable the batteries to have longer life. My 2010 Prius used to do it too. Apple is now doing this with iPhone batteries too, I believe.
Click to expand...
At the top end, this is correct. According to my BlueDriver diagnostic tool, the highest charge on the driver display, 8 out of 8 bars, is actually 80% of actual battery capacity. If you want to maximize the life of these batteries, you don't want to charge them to literally 100%. This 80% rule of thumb is endorsed by most EV makers, isn't something made up by Toyota.
 
#8 ·
rdgrimes said:
Normal operating range for the battery display is 2 bars to 6 bars. (8 total) As a rule you should normally see it between 4 and 6 bars. You'll only see 7-8 bars after long downhill stretches.
Click to expand...
Just query 2020 RAV4 XLE Hybrid battery level when running on the freeway with 65mph and my battery level can only maintain at 4 bars and sometimes dropped to 3 bars. I knew that the motor also running at high speed but when to compare to my Prius and it will charge up to 6 bars. Is it normal?
 
#9 ·
sjcdcheu said:
Just query 2020 RAV4 XLE Hybrid battery level when running on the freeway with 65mph and my battery level can only maintain at 4 bars and sometimes dropped to 3 bars. I knew that the motor also running at high speed but when to compare to my Prius and it will charge up to 6 bars. Is it normal?
Click to expand...
Yes that sounds about right for that speed but so many factors come into play that its unpredictable. For example if you have the air conditioning on you might think the battery will be charged less but if the car recognises that running the engine for longer is necessary it might end up using surplus engine power to charge the battery at a greater rate. The engine will always be maintained within its correct operating temperature window and this will vary significantly with ambient temperature. Then again very few roads are exactly flat so engine and battery charging/drain will cycle quite frequently. I really like the control algorithms used by Toyota which are remarkably good at balancing fuel efficiency with driving responsiveness but leave the driver the final say.
 
#10 ·
Regarding the 2021 Hybrid AWD system - if the rear battery ever runs down the rear wheels will not have power and there will be no AWD. Is this possible? In another forum someone replied that the gas engine will recharge the rear battery whenever the rear battery gets low - like 20%. If I drive 20 miles at 10mph over sand, I don't want the AWD to give out.
 
#11 ·
It will never happen! AWD will always be available regardless of traction battery charge status. If you were to drive at 10mph for an extended period of time the ICE would cycle on and off as required to keep traction battery sufficiently charged.
 
#12 ·
There is no rear battery except for the aux battery. The traction battery for both front and rear electric motors is under the rear seat. The system will always maintain enough power in the traction battery to provide power for the rear wheels as well as a little extra power for quick acceleration when needed.
 
#13 ·
jweiler said:
Regarding the 2021 Hybrid AWD system - if the rear battery ever runs down the rear wheels will not have power and there will be no AWD. Is this possible? In another forum someone replied that the gas engine will recharge the rear battery whenever the rear battery gets low - like 20%. If I drive 20 miles at 10mph over sand, I don't want the AWD to give out.
Click to expand...
This concern has been brought up before, but I don't think anybody's ever actually tested it out to see what happens.

In the absolute worst case, it's probably possible to completely run down the battery. The generator (MG1) can produce up to 31 kW of power while the rear consumes up to 40 kW. So to spin the rear wheels at maximum power there has to draw at least 9 kW from the battery. There's a 1.6 kWh battery, so it could sustain this for less than 11 minutes. And in practice it's less than half that (the battery generally maintains a charge somewhere around 50 to 75% and isn't allowed to drain completely to avoid damage, and power is also used in the front as well).

However, that's not how the system works in practice. The rear wheels aren't simply running constantly at maximum power all the time. AWD is on-demand, meaning that the rear wheels will only apply power when there's slip. And that isn't necessarily going to be full power, either. As long as the average power stays below 31 kW, the generator will be able to keep up and maintain a minimum power level in the battery.

Look up the Alex on Autos video on towing with the RAV4 hybrid. It's not exactly the same thing, but it should show you what I mean. Towing also requires more from the electric system, adding extra power to get the weight up hills, etc., and one thing he notes is how well the battery level is maintained.

So, what would happen if you did somehow get the battery level that low? I'd love for someone to test this out! It's theoretically possible for AWD to work without any battery at all (just run the power directly from the generator to the motor), just at reduced maximum power, and I wonder if Toyota's electrical system supports that. I also wonder what protections and contingencies Toyota put in place for this (would it run at reduced capability, throw error codes, etc?).

I wouldn't worry about it. It's theoretically possible, but not in any situation you're going to encounter in the real world.
 
#14 ·
jweiler said:
Regarding the 2021 Hybrid AWD system - if the rear battery ever runs down the rear wheels will not have power and there will be no AWD. Is this possible? In another forum someone replied that the gas engine will recharge the rear battery whenever the rear battery gets low - like 20%. If I drive 20 miles at 10mph over sand, I don't want the AWD to give out.
Click to expand...
That is not how it works, the rear or 12volt battery only powers the computers up for start up and accessories.
 
#15 ·
My RAV4 is my third hybrid. The Prius C was the only one that I managed to deplete the battery and have the system fall back on pure gas power. This happened near the peak of a long, long ascent on I-70 near I-15. The power just suddenly cut, and my speed dropped from 80 down to about 55 for the final half mile or so, and then I reached the summit, and with the downgrade I had enough power to get back up to 80, and the battery quickly got back up to its operating charge level.
 
#17 ·
The other reason the battery is only rarely charged fully is that the hybrid management algorithm tries to keep the ICE operating within a fairly narrow range of speed and power that corresponds to best fuel efficiency.
 
Save
Reply Quote Like Like
#19 ·
wishk said:
One thing I've noticed is that short, slow drives in cold weather tend to fill up the battery. The engine will run for heat and the system will dump excess engine output to the battery.
Click to expand...
That is correct but it doesn't help MPG compared to warm weather. The engine has to reach operating temp and thus keeps running until it does even when it doesn't have to to propel the vehicle. For example, the engine will keep running at a stop light while in summer it wouldn't. The energy under this condition is directed to the battery which looks good on the dash (and is at least better than a non hybrid idling) but is not in the ideal range described by people in other posts. Thus, lower MPG in winter, especially if you do mostly short drives.
 
Save
Reply Quote Like Like
1 - 19 of 19 Posts
About this Discussion
18 Replies
16 Participants
Last post:
pikeviewer
Toyota RAV4 Forums
posts
1.1M
members
174K
Since
2004
Rav 4 World is the internet's largest Toyota Rav4 SUV and EV online forum community. Discuss towing, modifications, and more.
Full Forum Listing
Explore Our Forums
4.3 General 4.3 Mechanical 4.5 RAV4 Hybrid (except Prime) 4.5 RAV4 Prime 4.3 Exterior