On my 2020 Highlander at least there's a setting in the vehicle menu where you can set how long you want it to stay off when stopped, I believe it's looking more at it from a climate/interior comfort standpoint, I think it was some scale like Min/Normal/Max.

But if you're getting a Battery Charging message after it turns on, that would make me think something is up. Mine usually turns back on after a minute and a half stating it turned back on for "Climate Control"

Can you tell what type of battery you have in the car? Is it Toyota Branded? From what I understand you want a AGM (Absorbed Glass Mat) type battery for Start/Stop engines, not a traditional "Flooded Battery" I replaced my Toyota Battery with an Interstate AGM battery and seemed to add about 15-30 seconds onto the stop time at lights, but now that i've had the battery a while seems to be staying off for shorter durations.

 

Can you tell what type of battery you have in the car? Is it Toyota Branded? From what I understand you want a AGM (Absorbed Glass Mat) type battery for Start/Stop engines, not a traditional "Flooded Battery" I replaced my Toyota Battery with an Interstate AGM battery and seemed to add about 15-30 seconds onto the stop time at lights, but now that i've had the battery a while seems to be staying off for shorter durations.

The vehicle is six months old and the battery is the OEM Clarios EFB. I tested it when new and again a week ago and saw no degradation in the tested CCA, which was above spec. The problem is that the typical charge voltage is only 12.4V. This increases to about 13.6V during deceleration or at night with the lights on. It also very occasionally rises to 14.4V (equalize charge?) but soon after falls back to 12.4V unless the lights are on. When "charged" to 12.4V, as soon as the engine shuts off at a light, the voltage drops to 12.25V or thereabouts and then decreases linearly. Often, it will hit 12.0V in 30 seconds or less, which causes the engine to restart for "battery charging".

The battery is in warranty for another 2.5 years so if it gets worse I will likely be able to get a warranty replacement. But the root cause seems to be the way the vehicle starves the battery and never EVER fully charges it.

I tried pursuing this through Toyota and rapidly reached a dead end. I reached out to Clarios, who informed me that sustained operation at < 50% charged will degrade the battery. The dealer says they see nothing wrong but no one will comment on the inability to keep the engine shut down for more than 30 seconds without needing to re-start.

The purpose of this thread is to try to gather some data points from other users. For example, my 2017 HL NEVER re-started for "battery charging" until the battery was >4 years old. At that point it tested at about 400 CCA and I replaced it with a conventional flooded battery and THAT battery NEVER re-started for "battery charging".

Paul

 

Turn everything off and see how long it takes, especially air conditioning if it is running or heart if it is cold (engine).

 

The times I report are typical for fall weather..... HVAC fan running at low speed but no AC. In fact, they are probably typical for any weather since engine off, only the HVAC fan runs, and it slows down when the engine stops. Remember, the behavior I am reporting is NOT due to HVAC..... the dash display says the engine re-starts because the battery is low.

I'm just trying to get some comparative information. Obviously the vehicle electrical loads will drain the battery when the engine stops. The question is.... is my experience typical.

One possibility I have not fully explored is the possibility that the system charges the battery to a higher voltage if start-stop is heavily used. I have a fairly light foot on the brake and very rarely trigger an engine stop. I need to see if anything changes if for example I trigger an engine stop EVERY time I come to a stop and do so for, say, a week.

Please bear with me for obsessing on this. Starving the battery doesn't make sense and worse, seems likely to harm the battery. Toyota is opaque on the subject. I love the car but this is driving this retired engineer nuts

Paul

 

You need the 12 volt battery load tested. It should carry more than 12.4 volts. Perhaps, try charging it overnight on a slow charge with an automatic charger. If it never charges to full charge or drops voltage by itself before connecting it back up, that battery is starting to get weak and use your warranty on it.

 

The point is that the VEHICLE never fully charges the battery. It very carefully keeps it at 12.4V unless the lights are on or I am decelerating. This is not a battery issue, it is a software issue.

Paul

 

Are you running in Normal drive mode or Eco mode? I recall a lot of discussion in 2020 about this issue and people found that Eco doesn't like to put much effort into charging the battery. For that reason it's better to use Normal mode.

 

100% in normal mode. Nice thought though

Paul

 

Here's an update. The other day I ended up in some stop and go traffic. Since I was using radar cruise, the engine shut off each time we came to a stop. After a couple stops, I noticed that the engine was re-starting after less than 30 seconds with the "battery charging" message. Traffic would move for maybe 30 seconds and then stop again, and each time, the engine re-started sooner and sooner. After maybe 10 minutes of stop and go, it would restart after about 10 seconds for "battery charging".

I have an aftermarket voltmeter in the 12V power outlet so I can monitor the voltage. Engine-on voltage was 12.4. When the engine shut down, the voltage dropped to about 12.2V and then rapidly decreased from there. When it reached about 12.0V (after as little as 10-15 seconds), the engine re-started for "battery charging". I watched it to see if it eventually would charge to something above 12.4V but AT NO TIME during the stop and go driving did it ever charge higher than 12.4V.

I have complained to the dealer and to Toyota "customer care" before about this and supplied full details including voltage measurements. Toyota merely refers me to the dealer. The dealer says everything checks out fine.

This CAN'T be right? What is the point of adding start-stop to the vehicle if the system keeps the battery so chronically under charged that the engine can't stay stopped for longer than a stop light cycle???

Paul