2021 Toyota RAV4 - recharging issue

After 3 days of standstill I had a flat battery from a PHEV. Leakage current is 50 mA, so no cause of problem. Charging voltage check shows that the battery is rarely charged. While driving you measure 12.6 V for 90% of the time. Occasionally you read 14.4 V or 12.8 V as the charging voltage. Is this normal ? The battery is found to be good after a charge.

12.6/12.8 seems too low.
I would have the service center at your dealership check the charging system while it is still under warranty.


Thanks for your response.

The service center has checked error codes (no codes) and battery condition. Their conclusion was that the battery was good and just needed a good charge. If the problem occurs again, you can always come back… . They can only change the battery if there is an error code. There is a TSB concerning 12V battery charging problems, but they need an error code.

Not being satisfied with this explanation, I’m checking myself what’s going on. But for that I need brand information, such as what the charging voltage looks like on this vehicle.

Maybe the way the battery is charged is good, because the 12V battery is only needed to activate the READY mode and to provide the power in rest. In READY mode, all consumers operating on 12V are powered by a DC-DC converter.

But I would like to know more about that. Now I look at the battery voltage every 24h to see how it evolves. So far so good.

Battery charging algorithms have become very complicated in newer cars like yours which have a lot of electrical operated gadgets and gizmos. Done to improve mpg and reduce emissions, extend battery life. That reading would indeed be unusual in my 30 year old Corolla and 50 year old truck, but I expect on your car it just means it is doing its job. If the battery consistently measures below 12.6 volts before the first start of the day, then you may have some sort of problem lurking. Otherwise, just drive and enjoy your almost new car.

I’m not sure what a PHEV is tho. 50 ma everything-off current is well within specs.

It doesn’t sound like your service people have checked the charging system. Find another vehicle and measure its charging voltage.

Good idea! But I don’t have that option.

Sure you do. Go to a dealer take one for a test drive and stop by an auto parts store that does charging system/battery checks.

I don’t like to guess but it may be that there is not a problem and you are making too many short trips . You might try to not concentrate on the charging volts and see if the vehicle starts and you make at least a long drive 2 or 3 times a month . After all you still have warranty left abd you might buy one of those small rechargeable jumper things to carry with you.

plug-in hybrid electric vehicle

Volvo - V70: this could be the right explanation. The receptionist of the workshop gave me the same answer

Efter all, everything about that car is made to gain energy. A small rechargeable jumper is a good idea, but requires at least 30% battery capacity.

It’s now been 3 days since I left the car and the voltage has gone down from 12.6 V to 12.4 V (10 °C = 50 °F). The 12.6 V is the voltage of a 100% charged battery I got from a 200 km (130 miles) car ride.
I find these measurements good but not excellent (every 0.1 V is the same as 10 % loss). In theory the battery will be empty after less than a month!

In December the car needs service. I hope to be able to talk to a technician about the charging curve of this car.

Then I will definitely link back to you.

Thanks for all the good suggestions!

Chances are there are none on the lot. The RAV4 Prime is in extremely short supply.

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I doubt an auto parts store will have the ability to check the charging system on this car.

Most dealerships–outside of CA–are unlikely to have any in stock.

When I went shopping for my Lexus NX 450h+, which is mechanically identical to the Rav-4 Prime, none of the dealerships in NJ or in nearby downstate NY had any in stock, or even in transit. When I drove to Allentown, PA, I was lucky to find a dealership that had 3 in transit, and one of them was in the exterior color that I wanted. I have been told that the Rav-4 Prime is even harder to get than my NX model.

It’s the thought that counts ! :grinning:

In stock or not, highly unlikely a dealership will allow an unaccompanied test drive. Used cars, yes, new cars, no.

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I wouldn’t expect a good, fully charged 12 volt auto battery to drain from 12.6 to 12.4 in 3 days. A 12 volt battery has another possible discharge path other than the cables. Acid on the surface of the battery case can conduct electricity directly from post to post and discharge the battery as well. Suggest to thoroughly clean the battery case of all surface contaminants.

If the 12.6 was a warm battery, I wouldn’t be surprised if it measure 12.4 when cold.


That sounds like a lot, especially if it’s smaller than a regular car starting battery.

I agree, but it’s not such a small battery: 55 Ah and 345 CCA (EN-norm).

oldnotdeadyet: I charged the battery slowly (10 h) with 8A max. The battery was not feeling warm at the end of the charging process. But nevertheless a good point to take notice of.