12v Battery Is Discharging, Re-Charge Now !

I was not charging.

 

Great work!

 

OK, I have a question for someone who has Carista on PRIME. I just bought a trial subscription for Carista to see if I can disable SKS in the car. I have this choice on Carista.



The item I thought would disable the SKS is the first item on the list under "Locking: Smart Key". I changed "Stop monitoring for car key signal after..." from default 5 DAYS to 0 DAYS. The problem is that even after this customization, the car still responds to the fob if I hold the driver's side door handle with a fob in my pocket. Does anyone have any idea why? I thought maybe 0 DAYS is not really immediate, but after some hours of inactivity, so I left the door locked overnight and checked to see if SKS is now disabled. But, again the car unlocks the driver's side door if I hold the driver's side door handle with a fob in my pocket. I am confused...

 

Does the tiny red LED on the FOB blink when near the door? If not then the car’s beacon is off. I think the beacon contributes to battery drain.

 

My fob has cover on and I can't see the LED on the fob, but that is a good suggestion. I will check that. Thanks.

That being said, if the LED does not blink thus the car's beacon is off, but still the touch to unlock the door function is working. So, what does that mean for the "Locking: Smart Key" to "Stop monitoring for car key signal after... 0 days"? What does that monitoring do as SKS function?

 

FYI doors need to be locked else beacon is off.
I think the same sensing turns the interior lights on as you approach the vehicle.

 

Yes, the door was locked. I just checked the fob without the cover. The LED did not blink as I approached the car. So, that means the the car's beacon is off. I don't think the dome light came on. Though I couldn't tell very well under sunshine. I left the "Turn on interior lights when smart key in range" option to default "Yes". I guess, that means the beacon is only used for the dome light, and touch to unlock either does not require the beacon or touching the door knob cancel the deactivation.

Assuming that is the case, I will see if the 12v battery drain is somewhat slower with the car's beacon off. I will report tomorrow on 12v SoC.

 

You could check directly, by putting a multimeter in series (between neg post and ground), measuring milliamperes, both with/without beacon active. Bit of a pain admittedly.

 

Without testing I think I would be surprised if the interior lights came on automatically when you approach the car when the car is not monitoring for the key signal.
It’s like the two settings are related. Theoretically you can set it to monitor for the key fob but not turn on the lights. Maybe?

 

Yeah, but I am trying to avoid disconnecting the 12v battery so I don't lose all the data points stored in the logs. However, my car is only a few months old, so if disconnecting is necessary, now would be a good time to do it, since it will not affect too much on the lifetime average.

I think you are correct on that you have to have the beacon active to have the light to turn on when approached with a fob. But, my question is if you keep the beacon on, and light function off, then what other functions are using the beacon? I can't think of anything else if the unlocking door is not one of them. And it seems clear now that the CARISTA customization to change "Locking: Smart Key" item "Stop monitoring for car key signal after..." from default 5 DAYS to 0 DAYS is not the same as turning off SKS by a dealer (or DIY using Techstream).

 

yeah, it seems to me that if sks is off, you would need to push the unlock button on the fob. that's how gen2 worked

 

Yeah, I may have to invest my time and (maybe more money) on TechStream. I have 3 different mini-VCI, but so far I have not had a luck in getting any of them working with the version of TechStream I downloaded.

 

Thought I would close the loop on some items in this thread.

(I've been swamped with non forum issues and unable to read or post for almost three weeks)

The Toyota dealer here replaced the OEM battery under warranty.

Despite the fact that I spoke with the service rep before making the appointment and when I arrived with the battery in the back seat and was told that the only thing necessary would be to test the battery, just testing the battery took almost four hours.

The mechanic testing the battery reported that in addition to the battery test showing that it was not recoverable, he determined that two of the cells had "shorted"

Add to that the fact that the instant a battery charger was attached after the battery went dead (to 2v) a large relay repeatedly attempted to close and repeatedly pulled the charger voltage down to 2v repeatedly releasing the relay, tells me that the Prime's system software is commanding 12v current demands without restriction (such as first looking at data such as battery voltage)

I monitored the 12v battery voltage for a number of days, both manually and using an BT OBD2 and the Torque app with the car parked and unused between observations. Note the voltage in the report (see below) The battery had been disconnected and fully charged overnight before taking it to the dealer.

Voltage observations over two weeks showed long periods of more than 12 hours with no discernible voltage changes other than some regular small "spikes" of less than 0.1v

These "periods" would then be interrupted with 12v battery decreases of more than 1v. On the Torque charts, when these large voltage drops were observed, the battery voltage would not "recover" as might be expected if something demanding current such as the car turning on systems when a keyfob was detected, then turning back off after a timeout.

Since the Torque App uses an OBD2 connection to record data, and the OBD2 connector is powered on when the car is OFF, I know that just the voltage monitoring by the OBD2 fob is making (I assume minimal) demands on the 12v battery, but that needs to be taken into consideration.

Over 50% of the readings that I made were made manually with the OBD2 fob disconnected from the 12v battery itself and the meter disconnected between readings, but, those readings essentially confirmed the readings made via the OBD2 connection.

During all of these observation periods, I was careful to assure that my keyfob was more than 50' away from the car.

I made separate 12v battery voltage observations both leaving the traction battery charger connected after the traction battery was charged and disconnected after traction battery charging was complete. I saw nothing that indicated any difference in the 12v battery voltages with the traction charger connected or disconnected.

Disabling SKS on the fob hows no effect on the 12v drain

I've been monitoring the 12v battery voltage manually with less frequency over the past three weeks but I am still seeing overnight voltage drops of over 1v between some readings unless the trickle charger is left connected. (I obviously don't want to ruin the replacement 12v battery)

Beverly Howard

 

Thanks for the posts on disabling SKS on the keyfob. These posts are right out of the Prius manual and the instructions (at least for me) are confusing, so, I took the liberty to edit them.

Activate Prius Keyfob Battery-Saving Function

• <Press/Hold> LOCK
• <Press> UNLOCK twice
• Keyfob light should flash two times then flash two more times
  
• Keyfob should then be deactivated.
• Test by assuring that Locking or Unlocking doors by touching door handles does not work.
• Keyfob battery depletion is minimized by preventing keyfob from receiving radio waves.
• Press any keyfob button to reactivate the keyfob
• The above From Page 288 of the 2020 Prius Prime Owners Manual

(Note, if you do the above near the car, the fob will also lock the doors.)

Additional related notes

The battery-saving function will be automatically activated in order to prevent the electronic key battery and the 12-volt battery from being discharged while the vehicle is not in operation for a long time AND the Keyfob has not been "near" the vehicle.

In the following situations, the smart key system may take some time to unlock the doors.

• The electronic key has been left in an area of approximately 6 ft. (2 m) of the outside of the vehicle for 10 minutes or longer.
• The smart key system has not been used for 5 days or longer.
• If the smart key system has not been used for 14 days or longer, the doors cannot be unlocked at any doors except the driver’s door.
• In this case, take hold of the driver’s door handle, or use the wireless remote control or the mechanical key, to unlock the doors.

fwiw, after finally learning how to do the above, I regularly disable the Keyfob. Since pressing any key re-activates the keyfob, it's easy to do so without taking the keyfob out of a pocket.

Beverly Howard

 

Glad to hear that you can get a new battery under warranty. Your observation seems to match mine in most part. One question is that if you know "Disabling SKS on the fob hows no effect on the 12v drain" which I also found to be true, then why are you bothering to disable the fob SKS? As the manual states, it is for conserving battery in the fob and do nothing to save the 12v battery drain.

 

>> why are you bothering to disable the fob SKS? <<

Because the Prius activates car systems when the fob comes close to the vehicle.

While I do not know how much current is consumed in these encounters, I do hear electric motors running and other system sounds when I come close to the car.

In my case, my shop is adjacent to the car so I am often in range with no intention to using it, so, if nothing else, just to reduce those events.

I'm still looking for causes and possible solutions even though they will probably have to come from Toyota.

It's absurd in 2020 to have a brand new vehicle that is electric based and still be required to provide additional battery charging with the expenditure of the owners time and equipment just because they, for whatever reason, don't drive every day.

Beverly Howard

 

As I commented in #223. I used CARISTA to disable CAR to look for key for signal, but this too had no effect on 12v battery drain. So far I have not found any single factor that can eliminate the 12v battery drain. It must be cumulative effects of many things that turns on while PRIME is parked and not activated.

 

>> this too had no effect <<

As a professional software programmer since the early 80's it's obvious to me that this is a software BUG that needs to be fixed.

I don't have the equipment necessary to identify exactly what's happening, but, Toyota does and someone needs to get their attention and they need to step up and track this problem down.

This forum alone now has a wealth of documentation that the problem exists and some clues but we might as well be talking to a wall as far as Toyota is concerned.

First, and, if this keeps up, last Toyota I'll ever own. It's a shame since the car has so many positives that are completely obscured by Toyota's unresponsiveness.

Beverly Howard

 

is the dealer going to analyze your car?

 

>> is the dealer going to analyze your car? <<

I offered to help in any way that I could. I documented my case as best I could.

I sent the service manager a link to this and other battery failure threads on this forum, but I didn't receive a response nor acknowledgement of any kind...

...so, probably not.

Beverly Howard