I got the dreaded 'Electrical Drain' warning message

[kamorela]

Well I finally got this message yesterday, oh joy:

Because I do have two "after market (sic) devices" I thought I should look into it.

But first, this:

(OK, better now.)

Aftermarket Device #1:
I have a hardwired dash cam, power for which comes from two fuse taps in the passenger foot-well fuse box. One - a switched tap - is for driving mode, i.e. vehicle power button is 'on' and the other - an unswitched tap - is for parking mode, i.e. vehicle power button is 'off'. Both circuits are integrated and controlled by an inline brain box that does two things: (1) it provides power to the camera when the vehicle is turned off (i.e. vehicle is 'parked'), and (2) it has a user-adjustable cut off function to prevent excessive battery drain when the unswitched 'parking' circuit is active. My cut-off is set at 12.4V. So then, when my vehicle is turned 'off' the unswitched parking circuit activates to provide vehicle-off camera power. So in parking mode, whether the camera is actively recording or not, it remains 'on'. To preclude unwanted video recording of the inside of my garage when I return home, or any other time I don't want or need parking mode recordings, I installed an inline kill switch to open the parking mode circuit (my unswitched circuit). My habit is to actuate the kill switch when I arrive home, but there have been times when I either forget or I clumsily don't actuate the switch when I think I have (it's a mini-push button style switch). In those instances, the 12.4V cut-off has worked as advertised to prevent battery drain and I've never had an issue with low voltage. Ever.

For clarity, my kill switch was actuated (power was off) in the time frame of receiving the 'Electrical System Drain' message.

Aftermarket Device #2:
I installed a Bluetooth (BT) 12V battery monitor so I could check my battery voltage at any time when I'm within BT range. At home, which is where I was when I received the message, I'm always withing BT range. Note: to check battery voltage BT must be activated in the monitor app. After checking battery voltage I always - ALWAYS - disconnect BT. I don't know if closing BT matters but in my own mind I'm removing a possible drain route. But because the monitor is hard-connected to the battery terminals, there could be some sort of static drainage I don't understand. (?)

Weirdness:
When I got the battery drain message I immediately checked my battery monitor app where I expected to see a horrifyingly low battery voltage, but instead it showed 14.3V and battery charging! My car was not plugged in to its wall charger, so WTH (What The Heck), how was my 12V battery being charged? Was there some update that tells the High Voltage Battery to take care of its little sister if it becomes anemic? Or what? I'm stumped.

Well in any event, after verifying the car would start, I was too tired to make sense of it all, so I plugged in my charger and went to bed, as any anxiety-prone person would do. This morning? -> all good. Chalking it up to X-Files weirdness.

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[Space_Pony]

It could be that the charge in your LVB was low enough that HVB was charging the LVB. It's designed to automatically charge the LVB if it needs a charge. Your MME is young to be experiencing issues like this. How many miles does it have? Do you drive it daily?

 

[CTZ]

I get this message all the time and I have a dashcam and also an OBD reader. All these accessories use the LVB and the HVB will charge it as necessary. The power usage of these accessories relative to the size of the HVB is trivial.

 

[Teslaeata]

Well I finally got this message yesterday, oh joy:

Because I do have two "after market (sic) devices" I thought I should look into it.

But first, this:

(OK, better now.)

Aftermarket Device #1:
I have a hardwired dash cam, power for which comes from two fuse taps in the passenger foot-well fuse box. One - a switched tap - is for driving mode, i.e. vehicle power button is 'on' and the other - an unswitched tap - is for parking mode, i.e. vehicle power button is 'off'. Both circuits are integrated and controlled by an inline brain box that does two things: (1) it provides power to the camera when the vehicle is turned off (i.e. vehicle is 'parked'), and (2) it has a user-adjustable cut off function to prevent excessive battery drain when the unswitched 'parking' circuit is active. My cut-off is set at 12.4V. So then, when my vehicle is turned 'off' the unswitched parking circuit activates to provide vehicle-off camera power. So in parking mode, whether the camera is actively recording or not, it remains 'on'. To preclude unwanted video recording of the inside of my garage when I return home, or any other time I don't want or need parking mode recordings, I installed an inline kill switch to open the parking mode circuit (my unswitched circuit). My habit is to actuate the kill switch when I arrive home, but there have been times when I either forget or I clumsily don't actuate the switch when I think I have (it's a mini-push button style switch). In those instances, the 12.4V cut-off has worked as advertised to prevent battery drain and I've never had an issue with low voltage. Ever.

For clarity, my kill switch was actuated (power was off) in the time frame of receiving the 'Electrical System Drain' message.

Aftermarket Device #2:
I installed a Bluetooth (BT) 12V battery monitor so I could check my battery voltage at any time when I'm within BT range. At home, which is where I was when I received the message, I'm always withing BT range. Note: to check battery voltage BT must be activated in the monitor app. After checking battery voltage I always - ALWAYS - disconnect BT. I don't know if closing BT matters but in my own mind I'm removing a possible drain route. But because the monitor is hard-connected to the battery terminals, there could be some sort of static drainage I don't understand. (?)

Weirdness:
When I got the battery drain message I immediately checked my battery monitor app where I expected to see a horrifyingly low battery voltage, but instead it showed 14.3V and battery charging! My car was not plugged in to its wall charger, so WTH (What The Heck), how was my 12V battery being charged? Was there some update that tells the High Voltage Battery to take care of its little sister if it becomes anemic? Or what? I'm stumped.

Well in any event, after verifying the car would start, I was too tired to make sense of it all, so I plugged in my charger and went to bed, as any anxiety-prone person would do. This morning? -> all good. Chalking it up to X-Files weirdness.

The 14.3Voltage is that of the charger, not the 12V battery.

There are specified locations in the electrical system to hard-wire connect accessories, departure from specifications is likely to cause issues however clever you think your own connections are.

 

[kamorela]

The 14.3Voltage is that of the charger, not the 12V battery.

Understood. My confusion, though, was that the battery was being charged at all. I didn't know the car did that.

There are specified locations in the electrical system to hard-wire connect accessories, departure from specifications is likely to cause issues however clever you think your own connections are.

Where are these 'specified locations', are they identified as such? How do I find them? If the battery drain message was not just some glitch, it seems most likely related to the dash cam and, if so, I want to rewire my dash cam to the appropriate 'specified location'.

I also just remembered that I have an insurance monitoring dongle in my OBD port. My insurance is mileage based, and in order to receive reduced insurance cost, I have to keep that dongle in place. Could it be the phantom battery drain with the car turned off?

Thanks for your insights.

 

[kamorela]

I get this message all the time and I have a dashcam and also an OBD reader. All these accessories use the LVB and the HVB will charge it as necessary. The power usage of these accessories relative to the size of the HVB is trivial.

So maybe I shouldn't be concerned?

 

[Teslaeata]

Understood. My confusion, though, was that the battery was being charged at all. I didn't know the car did that.

Where are these 'specified locations', are they identified as such? How do I find them? If the battery drain message was not just some glitch, it seems most likely related to the dash cam and, if so, I want to rewire my dash cam to the appropriate 'specified location'.

I also just remembered that I have an insurance monitoring dongle in my OBD port. My insurance is mileage based, and in order to receive reduced insurance cost, I have to keep that dongle in place. Could it be the phantom battery drain with the car turned off?

Thanks for your insights.

They’re buried somewhere within this document, also means whatever you connect goes through the battery management system………

 

[kamorela]

It could be that the charge in your LVB was low enough that HVB was charging the LVB. It's designed to automatically charge the LVB if it needs a charge. Your MME is young to be experiencing issues like this. How many miles does it have? Do you drive it daily?

I didn't know the HVB could charge the LVB if it's low. How neat is that? I learn something new every day in this forum.

And I don't drive all that much, I'm retired and mostly a home body. I bought my car new in November 2024 with 17 miles on it (it was a demo model). It now has 8,278 miles on it. A week from today I will have owned it for a year and a half.

 

[kamorela]

They’re buried somewhere within this document, also means whatever you connect goes through the battery management system………

Holy schmoly, that's a lot to sort through. Thankfully I have the time and motivation. Thanks so much!

 

[Teslaeata]

That police modifier document describes the parameters where charging starts, when, why and why it may not start in certain circumstances.

The %age SoC rates may have changed since it was written i seem to recall but still provides a good enough idea, the specifics are not that essential unless you’re working with them.

 

[Teslaeata]

Holy schmoly, that's a lot to sort through. Thankfully I have the time and motivation. Thanks so much!

Enjoy

 

[CTZ]

So maybe I shouldn't be concerned?

I wouldn't be. The power drain from your accessories is miniscule compared to the massive battery under the car. Now that the software charges the LVB when it needs it, it's basically a moot point. The LVB is constantly charging when the car is on, anyway, since it pretty much runs on 12V other than the powertrain. Just like an alternator in an ICE car.

 

[JimmyMachE]

I get this message all the time and I have a dashcam and also an OBD reader. All these accessories use the LVB and the HVB will charge it as necessary. The power usage of these accessories relative to the size of the HVB is trivial.

They constantly cycle the minuscule 12V battery, its usable capacity is 50% of the rated Ah. When the 12V battery is drained from 100% to 50% 12V SOC, it means a full cycle for a lead-acid battery.

12V lead-acid batteries typically offer 200–500 full charge cycles.

[EDIT: added the 12V SOC]

 

[Teslaeata]

They constantly cycle the minuscule 12V battery, its usable capacity is 50% of the rated Ah. A 100% to 50% SOC is a full cycle in a lead-acid battery.

12V lead-acid batteries typically offer 200–500 full charge cycles.

How many for Stangy at 58mths & 125,000 miles

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