Prius Prime 12v dead, what to do after?

>> Then disconnect the charger, and continue to monitor. <<

That's on my 2do list... but will probably wait until I have collected some voltage logs.

In addition, this car will probably tip me over the edge to replace my AC only clamp on ammeter with an AC/DC reader.

I'm still on a quest to see if I can set up a reasonable way to log battery current, but, so far, have not found anything within my price range.

Beverly Howard

 

In this lengthy thread, I posted a result of my initial experiment on 12v SoC change during 3+ hours of traction battery charging. It was suggested that if the 12v SoC was lower than I had, it might have charged a bit more. But that experiment has to wait for a while. I am currently testing the effect of switching off SKS from the fob, to see if that changes daily drain on 12v battery while the car sits undriven for a week.

12v Battery Is Discharging, Re-Charge Now ! | Page 10 | PriusChat

 

>> I am currently testing the effect of switching off SKS from the fob <<

I've spent a lot of time in that thread, but didn't see how to do this... would you elaborate?

Another observation (already mentioned) is that when the battery was completely dead and the 10amp charger was attached to the 12v battery, a relay somewhere on the passenger side of the engine compartment started trying to engage... the draw on the charger was significant enough to cycle the amperage draw from the charger from around 2amps to 8amps each time the relay tried to activate (not an accurate reading from the analog needle suffering under stress)

Can't remember, but, I think what I did was switch the charger to low (maintenance) mode and left it until the battery level came up to allow the relay to stay closed.

Beverly

 

Yeah there are too many dead 12v battery threads up, I have lost track of which one I have posted what comment. You can read up from this comment down. 12V Battery Died after a surprisngly short time... | Page 2 | PriusChat

My understanding is that the fob setting to disable SKS is to save the fob battery but not the 12v. In order to turn off the SKS in the car, you have to take your car to a dealer (special customization) or DIY with Techstream or Carista. I am now testing fob disabling SKS. if that shows no effect on the 12v drain, the next step is to turn the SKS off on the car using Carista.

 

It seems pretty clear from the manual that the "press unlock twice while pressing lock" function on the fob has nothing to do with the 12v battery in the car. The manual says that this is the "Electronic Key Battery Saving Function", and that the action is "stopping the electronic key from receiving radio waves". Nothing about being anywhere near the car. It is something you can do to extend the lifetime of the battery in the fob if you know that the fob is not going to be used for a while. The receiver is turned back on by pressing any of the buttons on the fob.

 

Thanks for the keyfob disable info. I've been through the manual several times and missed that one.

At the very least, it should allow me to stop leaving the fob at the other end of the house when I work on the car.

I've had what looks like success on the voltage recording as well.

The OBD2 port is powered with the car in the "Power OFF" state, and Torque shows the two voltage level readings (Voltage Control Module and Voltage OBD Adapter) available that I am looking for and with more accuracy (0.1v) than I need for this quest.

I'm looking for evidence of sudden 12v battery voltage drops from something switching on. In addition, I'm trying to document the system behavior with the traction charger attached and disconnected.

So far, I cannot see any evidence that watching these via ODB2 has activated any other functions or battery consumption.

I have had a voltage graph of both voltages running for several hours. It looks like the Voltage Control Module is all I need, but the two pretty much validate each other although the OBD voltage appears to be the result of a digital switching process.

I've also been careful to keep the keyfob out of range during all of this snooping setup and learning process.

Thanks again,
Beverly Howard

 

Has anyone had the dealer disable the smart key system? Does that have a significant effect on the 12V discharge rate?

 

That is my next experiment on the list. After I check fob disable SKS which should have no effect on 12v, I will use Carista to disable the SKS. However, the manual statement suggest that SKS is automatically disabled after 5 days of inactivity. I have not had my 12v depletes down to the low level that car can not be started in 5 days of parking. After 5 days, SKS may not be draining any more 12v SoC.

 

BOOM! That's it.Thank you! I'd missed that warning in the manual. Never occurred to me it's doing additional stuff while still plugged in after the HV bat is full but it makes complete sense. The car does not know HV level unless it checks. It hasn't been a problem with my 12V but I've been guilty of leaving it plugged in for a day or two if I wasn't driving. I bet there are many, many (most) users doing this especially if they intend to preheat/precool before leaving, when ever that might be. Thanks. PS, I ordered 3 BM2's. End of may arrival.

 

Yeah, it is counter intuitive, especially if PRIME owners mistakenly think 12v battery gets charged form the wall "whenever" the charge cord is plugged in. In normal driving condition when you do daily drives, leaving a cord attached to the car for a couple of days over weekend is not going to be a problem. But for prolonged inactivity under COVID-19 stay-home period, any small drain on 12v over days could be lethal.

As for the 3 BM2's, I am not sure how the app will display three different data. Each has unique BT identifier, so it should not be a problem to distinguish them, but I don't know how it will manage displays and synches the data. I don't think the app can display more than one unit at a time. It has no two way hands-shake, so whenever your phone is within the BL range (the manual says 10m, but mine is more like 3m very short), the app will synch with the BM module and update the data. The question is what happens if there are more than one BT unit emitting data at the same time from the same distance. I think you have to pick the correct BT signal manually from the setting on the app.

 

Keep the 12 volt on a charger.

 

I did research on this and it depends on which of the apps you use. It's not pretty like the CTEK app where you can give them custom names but you just switch the Bluetooth source before launching the app. Set it so it does not run in the background. So you only need to note which vehicle has which BT ID when you set it up. It's only going to show one vehicle at a time, but that's OK.

The BM3 app is $9.99 and does do multiple vehicle monitor and display. I'll try cheap first and pay if needed.

 

I was not aware of the BM3 paid version of app. The original app that was suggested by the package was BM2 v3.01, but this app did not have data export functionality. I emailed the company about this functionality, but no reply. Then, I switched to older version of JMP BattMon II v2.0, this app has data export functionality. But this version must have bug that I can not keep the BT device name edited. Well, it can be edited, but every time it reconnect to the device, the app will revert back to unique BT ID the module send. Still, the utility of data export function is more important to me, so I am using older JMP BattMon II v2.0 for now. BTW, the module will send out the BT signal freely to any phone with compatible app installed. So, anyone with the app installed can read the historical data, and probably trigger the cranking test and charging test on the car. So, you do need to be aware of possible security risk.

 

Yeah, BT was never designed with security in mind. I used to run Bluejacking and Bluesnarfing tools to test our internal security. People are clueless when it comes to BT and the massive "cracked" door it provides into your devices.

The BM3 app looks like it solves the problems of the other apps with data export, device renaming, and multiple device monitor capability. I have a few of the free apps installed, I just need a BM2 to play with.

 

The saga continues.

• Recharged the (probably toast) battery yesterday, then used the car for about 20 miles with one stop of half an hour.
• Charged the traction battery and disconnected the charging cord when completed at about 4pm
• This morning, the 12v battery is completely dead again... showing 4v
• Bought a replacement battery (scheduled Toyota service for Monday)
• As mentioned in other threads, all vehicle settings were lost with the battery change... dash clock, etc.
• Reset most of them, but cannot determine how to set the "Battery Level" Display

The traction battery is fully charged. Plug in charger, and shows "3 blues" and stops charging. Console shows battery fully charged when ignition is turned off.



Any suggestions on getting The vehicle display level reactivated?

Also, any other settings that I should check?

FWIW, despite battery vendors claiming that they had no battery for the 2020 Prime, this battery has the same specs, dimensions and fits perfectly.

Champion Premium Battery, Group Size H4
Pep Boys Part#: H4-480CHP | SKU: 2283504​

Thanks in advance.
Beverly Howard

 

The display in the first image (the empty battery icon) normally shows the traction battery charge level, but it's now completely blank. I drove the car a few blocks thinking that it might detect the full battery level, but it did not.

More troubling, even though the traction battery is fully charged, the engine runs constantly despite the "EV, etc" settings and full traction battery. When driving, that icon shows alternating displays... i.e. some green in each of the bottom two sections and then back to blank.

Beverly Howard

 

Hopefully a new 12 volt battery will resolve all that.

 

Did you have to pay for the battery? I would think it should be covered by warranty. If you have to pay for it, how much?

The fact you can start the car means your 12v is not completely dead? I am bit confused how you got your display to show if the 12v is dead.

Same question as @Tideland Prius. I don't understand what display you want to "reactivate".

You are correct there are a few aftermarket batteries that fits PRIME size specification 140R/LN1/H4. This size group was very hard to find when the Gen4 and Prime first came out, but now not so hard to find it on-line.

 

You are using split screen MID. You can toggle the split screen selection using the wheel button. What is displayed on your split screen now is the small HSI gauge. It corresponds to the HSI bar as you accelerate or slow down, it has nothing to do with your traction battery charge.