Possible battery drain issue

[The Spider House]

I don't think so. The reset is only done to let the system know (or think) the battery is new. That parameter is stored and kept even if the battery is disconnected. Otherwise, it wouldn't need to be reset when replacing the battery.
The procedure is the same for all S550s.

Thanks for the response

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[Skye]

So update: did the BMS reset, let the car run for about 30 minutes yesterday. Went to start it today and it barely had enough power to turn the starter over, in dash voltage read 13.8V to 14.2V to 14.0V

Given the current situation, 30 minutes might not be enough. I can't say what the proper amount of driving is, but consider for any of us, starting the car pulls amperage. If dealing with a possible electrical issue, then starting the car, it's taking an additional step down.

The low voltage continues to concern me. If the charging system was working well, you'd see at least 14.5v in-dash, if not occasionally more. People are back from the holidays this week. When you have time, swing by a parts shop or dealer and get the alternator output and charging system checked. That testing good provides a baseline. You can then move on to other possibles, like isolating circuits or components.

 

[MiamiGT350]

So update: did the BMS reset, let the car run for about 30 minutes yesterday. Went to start it today and it barely had enough power to turn the starter over, in dash voltage read 13.8V to 14.2V to 14.0V

Your alternator and BMS seem to be working fine. The voltage will vary as the BMS attempts to prolong the life of the battery.

The actual battery voltage will display in the dash when the car is in accessory mode (electronics on, but engine off).

I would fully charge your battery and see if it keeps dying. If so, I think a new car battery is in your future.

 

[justa16yote]

Given the current situation, 30 minutes might not be enough. I can't say what the proper amount of driving is, but consider for any of us, starting the car pulls amperage. If dealing with a possible electrical issue, then starting the car, it's taking an additional step down.

The low voltage continues to concern me. If the charging system was working well, you'd see at least 14.5v in-dash, if not occasionally more. People are back from the holidays this week. When you have time, swing by a parts shop or dealer and get the alternator output and charging system checked. That testing good provides a baseline. You can then move on to other possibles, like isolating circuits or components.

I stopped at an Advance Auto and got it checked, my battery is fine, alternator is fine, but I was told my starter is showing early signs of going out

 

[Eyesac]

FWIW, any draw that can drain a battery from "charged" to completely dead in a day or even two generates some heat. If you have a friend with a temp gun or even better a IR gun with a display (most shops have at least one guy that has one), you'll see it. Straight up see it. You can point it at the fuse box and see which circuit, and follow the wire to the component...visually, it's rad.

 

[Eyesac]

I just googled it, they make cheap IR display USB-C phone adapters. I might have to buy one...

 

[justa16yote]

FWIW, any draw that can drain a battery from "charged" to completely dead in a day or even two generates some heat. If you have a friend with a temp gun or even better a IR gun with a display (most shops have at least one guy that has one), you'll see it. Straight up see it. You can point it at the fuse box and see which circuit, and follow the wire to the component...visually, it's rad.

I think what had happened was that I replaced my old battery without doing the BMS reset until the day after installing it, but even after doing it everything has been pretty good

 

[justa16yote]

ANOTHER UPDATE: just got home, was going to start it when this message was on my sync screen, car unlocked fine and everything, and then I heard the throttle body actuating and a clicking noise from the fuse box area, pulled the black relay in one of the pictures below, and it stopped, put it back in and it kept doing it, anyone have any ideas what it can be?

 

[BrakeFade]

Does the fuse box label describe what the relay is? Also, if you have electrical issues and you're trying to troubleshoot charging problems you're going to need a voltmeter. First thing when you see that error is check the battery directly and see what you're reading. If it less than 12.5 volts you definetly have battery drain issues. If you can start teh car, you need to see how much voltage is reading athe battery with the car on using your meter. It should be over 13.5volts. If you're seeing 13.5 turn on your AC and radio and read it again. It should be reading over 12.5 volts under load, and ideally 13 or more.

For that relay that is clicking, you need to use your meter and see if one side is hot with the ignition off. If it is hot and the relay is sticking, you could be draining that way.

 

[justa16yote]

Does the fuse box label describe what the relay is?

It says it’s the powertrain control module relay

 

[BrakeFade]

It says it’s the powertrain control module relay

If you have electrical issues and you're trying to troubleshoot charging problems you're going to need a voltmeter. First thing when you see that error is check the battery directly and see what you're reading. If it less than 12.5 volts you definetly have battery drain issues. If you can start teh car, you need to see how much voltage is reading athe battery with the car on using your meter. It should be over 13.5volts. If you're seeing 13.5 turn on your AC and radio and read it again. It should be reading over 12.5 volts under load, and ideally 13 or more. Low voltage will cause all kinds of weird gremlins to pop up. You have to be 100% sure your battery and alternator are working as they should or you'll be chasing your tail in circles.

For that relay that is clicking, you need to use your meter and see if one side is hot with the ignition off. If it is hot and the relay is sticking, you could be draining that way.

Another thing, a bad chassis ground can cause major electrical problems as well. I chased a bad ground on my old E34 M5 for months. Visibly, the ground looked fine but when i finally removed it, the backside was completely corroded. Replaced and everything began working like new again. So checking your chassis grounds would be a key step as well.

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