[tazam2]

2018 here.
Just changed my original battery at the dealer for “increased battery drainage”. They said battery health and charge were ok, but an issue at load.

This morning another notification.
“Increased battery drain when stopped”.

Anyone encounter this issue?

[lax01]

2017 and I let the car sit (unfortunately) - I get this warning on on occasion but simply driving it seems to make it go awhile

[tazam2]

error kept reappearing.

Took it to the dealer and the battery was changed (original 2018 batter). Error showed up once again the next morning.
However, error free for the past week.

[F87source]

You might have high parasitic battery drain. Perform a parasitic battery drain test with a multimeter and report the results. IIRC the drain should be in the 50mA range and IIRC the battery drain warning comes on at 100mA of drain. So if you find you have excessive parastic draw you will need to perform the test while pulling fuses till you see the draw drop, then isolate what is running on that fuse is causing all this drain.

[bimmerdriver2]

Originally Posted by F87source

You might have high parasitic battery drain. Perform a parasitic battery drain test with a multimeter and report the results. IIRC the drain should be in the 50mA range and IIRC the battery drain warning comes on at 100mA of drain. So if you find you have excessive parastic draw you will need to perform the test while pulling fuses till you see the draw drop, then isolate what is running on that fuse is causing all this drain.

I have an HP/Agilent 6033A laboratory power supply which I use as a battery charger. I periodically charge the batteries on my cars to keep an eye on the health of the batteries and also to extend the health, since the batteries normally do not get a deep charge from short trips.

I recently charged the battery of my M2C and after charging at 14.4 V, I let it float at 13.6 V for an extended period of time. After several hours, the draw reported by the power supply was 260 mA. My ML350 draws around 350-400 mA after an extended float and my ex-E46 M3 would draw around 150 mA after an extended float, so 250 mA on the M2C seems reasonable. I didn't disconnect the battery to see what the vehicle itself was drawing, but I would be surprised if the battery was drawing more than 50 mA, leaving 200 mA for the car. Just to be clear, the vehicle was turned off while I was doing this.

My point is that I think the current draw from the vehicle is considerably more than 50-100 mA, solely based on my recent experience with my M2C.

[F87source]

Originally Posted by bimmerdriver2

I have an HP/Agilent 6033A laboratory power supply which I use as a battery charger. I periodically charge the batteries on my cars to keep an eye on the health of the batteries and also to extend the health, since the batteries normally do not get a deep charge from short trips.

I recently charged the battery of my M2C and after charging at 14.4 V, I let it float at 13.6 V for an extended period of time. After several hours, the draw reported by the power supply was 260 mA. My ML350 draws around 350-400 mA after an extended float and my ex-E46 M3 would draw around 150 mA after an extended float, so 250 mA on the M2C seems reasonable. I didn't disconnect the battery to see what the vehicle itself was drawing, but I would be surprised if the battery was drawing more than 50 mA, leaving 200 mA for the car. Just to be clear, the vehicle was turned off while I was doing this.

My point is that I think the current draw from the vehicle is considerably more than 50-100 mA, solely based on my recent experience with my M2C.

That's great to know!

From another thread I was seeing a bmw tech say the drain was sub 100 MA, so that info might not be correct.

[bimmerdriver2]

Originally Posted by F87source

That's great to know!

From another thread I was seeing a bmw tech say the drain was sub 100 MA, so that info might not be correct.

I'm very curious how the tech came up with this value, whether it was just a guess or it was actually measured. I never saw such a low value on my E46 M3, which has much simpler electrical system.

Again, I want to qualify that by saying the battery was still connected, floating, but the current draw on a floating healthy battery isn't very high. For a newer vehicle that has a TCU, there will be higher current draw, because the TCU is always operating, even if the ignition is turned off. If the doors are locked, the alarm will be operating. Etc.

[F87source]

Originally Posted by bimmerdriver2

I'm very curious how the tech came up with this value, whether it was just a guess or it was actually measured. I never saw such a low value on my E46 M3, which has much simpler electrical system.

Again, I want to qualify that by saying the battery was still connected, floating, but the current draw on a floating healthy battery isn't very high. For a newer vehicle that has a TCU, there will be higher current draw, because the TCU is always operating, even if the ignition is turned off. If the doors are locked, the alarm will be operating. Etc.

I'm not sure, but the tech guy said when everything is on sleep mode power draw is extremely low.

I want to check ista but haven't had the time yet to dig through it all.

[tazam2]

Well so far no solution

Replaced the original battery from 2018
Updated the ISTA… https://static.nhtsa.gov/odi/tsbs/20...46765-9999.pdf