[brichi]

Hey guys

So I just had my battery replaced by BMW and registered about 2 months ago, I noticed 3 days ago I got a warning when I got home to leave engine running cause the battery discharged or something to that effect, don't remember the exact words but it was close to that

anyway, I went into the hidden menu so I can watch the voltage and in the morning before I start the car its at 12V, while driving it fluctuates between 14.5 at 15V but my question is when I start the car, the initial draw drops to like 10V's, is it normal to drop that low? from what I have read the voltage should never drop below 12V.

Thanks for any input!

PS: I did have a Verizon jetpack for wireless wired right to the battery and fused so its always on even when car is off but I cant see that causing an issue, it barely draws any power. I have it unplugged for now as a test but the error for the battery only came up once or twice so its tough to trouble shoot AND it was like 10 degrees out in NY so maybe the cold is playing a big factor on it which I know can effect the battery

[Billfitz]

It's not unusual to see a voltage drop when starting, because of the draw of the starter. What's more of a concern is the 12v reading in the morning. It should be in the vicinity of 13v. Even discounting your jetpack the electronics in a BMW are never truly off, they're always drawing current. That, along with the lowered capacity of batteries when cold, is why I plug in my battery maintainer every night when the temperature goes below 20, or when the temperature goes below 30 if I'm not going to be driving for a few days or more. I have mine set up with a quick disconnect plug attached to my lower grille, wired to the under hood charging posts, so I never have to open the hood to plug it in.

[cfm56d7b]

The combination of unusually cold weather and continuous power draw from BMW and non BMW electronics can put the battery over the edge. I'd monitor it for a few days.

Do you have a dash cam with a fused connection to the main battery? It's always good to ask.

I prefer to have a second battery for accessories such as Cellink NEO.

[brichi]

Originally Posted by Billfitz

It's not unusual to see a voltage drop when starting, because of the draw of the starter. What's more of a concern is the 12v reading in the morning. It should be in the vicinity of 13v. Even discounting your jetpack the electronics in a BMW are never truly off, they're always drawing current. That, along with the lowered capacity of batteries when cold, is why I plug in my battery maintainer every night when the temperature goes below 20, or when the temperature goes below 30 if I'm not going to be driving for a few days or more. I have mine set up with a quick disconnect plug attached to my lower grille, wired to the under hood charging posts, so I never have to open the hood to plug it in.

the battery should be 13V before I even start the car? I read in other threads 12-12.2 is the norm if the cars off for a few hours

thanks for the info!

[brichi]

Originally Posted by cfm56d7b

The combination of unusually cold weather and continuous power draw from BMW and non BMW electronics can put the battery over the edge. I'd monitor it for a few days.

Do you have a dash cam with a fused connection to the main battery? It's always good to ask.

I prefer to have a second battery for accessories such as Cellink NEO.

no dash cam, the only thing out of the stock stuff is the 12V USB plug I added to power the jet pack but I have had that for years

[HighlandPete]

Originally Posted by brichi

the battery should be 13V before I even start the car? I read in other threads 12-12.2 is the norm if the cars off for a few hours

thanks for the info!

My 535i typically shows ~12.3V, when locked and in sleep mode, after a couple of hours. (Connected leads under hood and I attach a Voltmeter). When open/awake and voltage checked from the lighter socket, can be ~0.5V lower.

Our batteries run around the 75 - 80% SOC range.

[supermarket]

Originally Posted by brichi

anyway, I went into the hidden menu so I can watch the voltage and in the morning before I start the car its at 12V, while driving it fluctuates between 14.5 at 15V but my question is when I start the car, the initial draw drops to like 10V's, is it normal to drop that low? from what I have read the voltage should never drop below 12V.

This alone doesn’t mean too much. 10V isn’t out of the ordinary for a cranking voltage.

But if you replaced your battery a couple of months ago (I guess it wasn’t holding a charge or wasn’t starting your engine) and are still seeing warnings about low charge or high drain, then I’ve got to assume something’s still wrong.

PS: I did have a Verizon jetpack for wireless wired right to the battery and fused so its always on even when car is off but I cant see that causing an issue, it barely draws any power.

I wouldn’t be so sure about that.

The way you’ve connected it sounds like a bad idea.

I have it unplugged for now as a test

the only thing out of the stock stuff is the 12V USB plug I added to power the jet pack but I have had that for years

Did you unplug the hotspot from the USB port, or did you disconnect the USB port from the battery?

The correct way to handle this would be to disconnect the port from the battery.

If the battery’s already been subject to full-time abuse from your USB port and hotspot, and particularly if you’ve encountered below-freezing temperatures, irreversible damage to the battery may have already occurred, and it may never hold the same charge that it did when it was new. (It’s also possible that the damage was minimal, it depends on how discharged the battery got, for how long, and how cold it was.) I mention this because if you’re just hoping that the messages about battery discharge will disappear after disconnecting the direct-wired USB port, they may not. It may have already killed your battery (just like it may have killed the previous one).

[brichi]

Originally Posted by supermarket

This alone doesn’t mean too much. 10V isn’t out of the ordinary for a cranking voltage.

But if you replaced your battery a couple of months ago (I guess it wasn’t holding a charge or wasn’t starting your engine) and are still seeing warnings about low charge or high drain, then I’ve got to assume something’s still wrong.



I wouldn’t be so sure about that.

The way you’ve connected it sounds like a bad idea.




Did you unplug the hotspot from the USB port, or did you disconnect the USB port from the battery?

The correct way to handle this would be to disconnect the port from the battery.

If the battery’s already been subject to full-time abuse from your USB port and hotspot, and particularly if you’ve encountered below-freezing temperatures, irreversible damage to the battery may have already occurred, and it may never hold the same charge that it did when it was new. (It’s also possible that the damage was minimal, it depends on how discharged the battery got, for how long, and how cold it was.) I mention this because if you’re just hoping that the messages about battery discharge will disappear after disconnecting the direct-wired USB port, they may not. It may have already killed your battery (just like it may have killed the previous one).

thanks! I did disconnect it from the battery. The other batter was 6 years old so definitely was on its way out either way from what I've heard on how long they last in normal use

[Billfitz]

Originally Posted by brichi

the battery should be 13V before I even start the car? I read in other threads 12-12.2 is the norm if the cars off for a few hours

In winter mine is at 13v, because I keep it on the tender. In summer it goes down around 12v, because I don't use the tender in summer. I don't use the tender in summer because that's when the battery works at peak performance anyway. All I can say for sure is that I drive very little in winter, usually less than 10 miles when I do, and I've never had a low voltage warning.

[Jadenkid22]

Isn't it a little excessive to literally charge your battery everyday overnight ?

I just got back from a trip in which i was away for 15 days and my 2013 F30 started right up and it still has the original battery from 2013!! I also live in NYC and it was below 10F degrees for a few days.

[desmat]

I've always had those "low battery", "battery discharged", "battery heavily discharged" messages during winter. First time I saw those messages I bought a Noco G3500 battery maintainer. Plugged it in and message disappeared. This was 2-3 winters ago.

This winter, I automatically have those messages when it is -15c(5f) outside or lower. When I plug in the charger, it says battery is at 100% but I leave the charger plugged in during the night (battery maintenance mode). Unplug the car, go to work. Park at work and get the messages again. As soon as temp goes up a few degress (let say -10c/14f). No more messages.

Car always starts on first crank too.

Note that my driver profile is not considered good by BMW as I'm not driving the car enough and doing lot of city driving.

So right now I've read that IBS can be faulty or even door handles can be faulty and drain.

The thing is that my charger always shows 100% when I plug it in ?
Not sure what to do next but go to my shop (not dealer) so they can check... the battery ?

[Billfitz]

Originally Posted by Jadenkid22

Isn't it a little excessive to literally charge your battery everyday overnight ?

I don't charge my battery every day. I plug in a tender, which provides the current that the car uses when the engine isn't running, so the battery won't discharge, which in cold weather best case shortens battery life, while worst case can cause the symptoms the OP is experiencing. I'm a firm believer in an ounce of prevention, especially when the twenty odd pounds of cure of a new battery runs around $200. I took that lesson to heart when the battery in my '07 didn't reach its third birthday.

This winter, I automatically have those messages when it is -15c(5f) outside or lower. When I plug in the charger, it says battery is at 100% but I leave the charger plugged in during the night (battery maintenance mode). Unplug the car, go to work. Park at work and get the messages again. As soon as temp goes up a few degress (let say -10c/14f). No more messages

I bet the system is looking at both the level of charge and the temperature, and knowing that it takes more effort to turn the engine over at lower temperatures it's being too aggressive about showing a message. I'd trust the charger's opinion. If you want a third opinion keep one of these or something similar in your glove box:



https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[desmat]

Thanks. I'm pointing to that direction too (system too aggressive). I've read some changed the limit via coding...
Ok nice will try that gadget ! You're never too sure I guess...