[viperdoc]

I haven’t had any issues with the 45e up to now. But yesterday my wife drove it about a mile away, after being fully charged. She parked in the shade, though it was 94 degrees out. Came back and the car unlocked ok but when she tried to start it the dash went completely black, then flashed numerous crazy messages about chassis failures and low battery warnings, followed by weird knocking from under the car somewhere and the brake pedal pulsated a bunch of times. Then…. Nothing… Completely dead. Not even the doors would unlock (from inside you could open them with the mechanical door handle). Towed to the dealer

I recall strange things like this happening to other members, some while they were driving. If something major happened to cause this, certainly I’m concerned. But if it is something small, I think I’m going to be even more concerned because it completely killed the car

[jad03060]

It could be as simple as the 12vdc battery is dead. First thing I'd try if it wasn't already towed away would be to try jump starting the vehicle. Everything pretty much still uses 12vdc parts except the EV drivetrain, so if there's not enough juice to keep all of the computers running when you try to start it, you'll get all sorts of weird symptoms, one of which is it won't start. Note, while jump starting the PHEV is possible and safe, using it as a source to jump start others is prohibited based on what the User's Manual says...the PHEV's ability to source the (maybe short-term) high current surge to start another vehicle is just not safe with the PHEV's 12vdc supply.

If it's something else, it could get more complicated.

[cobramite]

I kno wnext to nothing about these highly complex PHEV systems but it does sound like you very well could have a dead battery(12V).
As suggested above jump it and see what happens.

[viperdoc]

thanks all. I appreciate the input. If that is all it is, that would be wonderful. We already had it towed so hopefully today the dealership will say "just the 12V!!! It's all set!"

But we will see...i'll keep everyone updated

[jad03060]

In most of their vehicles, BMW does not try to recharge their 12vdc batteries to their full state...it might happen, but it takes a certain use pattern. On their ICE vehicles, the alternator is on a clutch, and normally only engages that during deceleration and braking. If the battery charge level gets below about 70%, it will actively try to bring it back up to at least to that point.

Periods of heavy 12vdc use, such as in the winter when batteries also have less capacity, the seat heaters, lights, and starting the vehicle can put a huge load on the battery. In the summer, it may need to use the cooling fan(s), and the a/c stuff could be running at maximum, again using lots of 12vdc. This is one reason why BMW uses AGM batteries, which are better at deep discharge than a standard wet cell. As opposed to a 'normal' vehicle, a long highway trip won't necessarily top off your battery. Contrary to common belief, lots of stop and go where you're decelerating and stopping (if those stops aren't too long!) has a better chance of topping the battery(s) up than highway driving.

It's not a bad practice to put a battery maintainer on the thing occasionally. You can then gauge the original state by how long it takes to bring it back up to full.

I did that on my first BMW with that functionality. The first battery only lasted a year. The second, after I started to use the maintainer, lasted 7 years. Quite a difference.

[kapsjt]

Originally Posted by viperdoc

I haven’t had any issues with the 45e up to now. But yesterday my wife drove it about a mile away, after being fully charged. She parked in the shade, though it was 94 degrees out. Came back and the car unlocked ok but when she tried to start it the dash went completely black, then flashed numerous crazy messages about chassis failures and low battery warnings, followed by weird knocking from under the car somewhere and the brake pedal pulsated a bunch of times. Then…. Nothing… Completely dead. Not even the doors would unlock (from inside you could open them with the mechanical door handle). Towed to the dealer

I recall strange things like this happening to other members, some while they were driving. If something major happened to cause this, certainly I’m concerned. But if it is something small, I think I’m going to be even more concerned because it completely killed the car

This just happened to my 50e. 3,000 miles. Everything was fine. Drove it Saturday with no issues. Full battery charge. Went out later that day and the doors wouldn't unlock. Nothing. No power to anything.

I called roadside assistance and we got the car started but every warning was flashing, most notably the chassis warning. They towed it to the dealership and they said it was most likely a dead cell in the 12v battery. They replaced the battery and I got the car back today. A frustrating issue on a 2024 with 3,000 miles. They did install drive 8.5 though so that was nice to get done.

[nZtiZia]

Originally Posted by kapsjt

This just happened to my 50e. 3,000 miles. Everything was fine. Drove it Saturday with no issues. Full battery charge. Went out later that day and the doors wouldn't unlock. Nothing. No power to anything.

I called roadside assistance and we got the car started but every warning was flashing, most notably the chassis warning. They towed it to the dealership and they said it was most likely a dead cell in the 12v battery. They replaced the battery and I got the car back today. A frustrating issue on a 2024 with 3,000 miles. They did install drive 8.5 though so that was nice to get done.

off topic, but do you happen to connect an iPhone via CarPlay? if so, any issues? many with iDrive 8 are reporting inconsistent connections and are hoping version 8.5 addresses/fixes the issue

[viperdoc]

Originally Posted by jad03060

In most of their vehicles, BMW does not try to recharge their 12vdc batteries to their full state...it might happen, but it takes a certain use pattern. On their ICE vehicles, the alternator is on a clutch, and normally only engages that during deceleration and braking. If the battery charge level gets below about 70%, it will actively try to bring it back up to at least to that point.

Periods of heavy 12vdc use, such as in the winter when batteries also have less capacity, the seat heaters, lights, and starting the vehicle can put a huge load on the battery. In the summer, it may need to use the cooling fan(s), and the a/c stuff could be running at maximum, again using lots of 12vdc. This is one reason why BMW uses AGM batteries, which are better at deep discharge than a standard wet cell. As opposed to a 'normal' vehicle, a long highway trip won't necessarily top off your battery. Contrary to common belief, lots of stop and go where you're decelerating and stopping (if those stops aren't too long!) has a better chance of topping the battery(s) up than highway driving.

It's not a bad practice to put a battery maintainer on the thing occasionally. You can then gauge the original state by how long it takes to bring it back up to full.

I did that on my first BMW with that functionality. The first battery only lasted a year. The second, after I started to use the maintainer, lasted 7 years. Quite a difference.

great advice. And you know... I actually have a maintainer that I haven't thought about hooking up because of how often the car gets driven

[tooloud10]

I agree that it sounds like a 12V battery issue as well. My BMWs have always been significantly harder on 12V batteries than any other car I’ve ever owned.

I remember a few years ago it got so bad that BMW quietly acknowledged that it was normal to replace the 12V battery on the E70 with the N63 V8 at every oil change.

[Tejas1836]

If you use a NOCO charger, they have a 10 ft QD cable and M6 eyelet terminal connector. I used these to permanently connect to the battery with one QD end behind the grill to hook up the charger without popping the hood. Simple.

[nZtiZia]

Originally Posted by viperdoc

great advice. And you know... I actually have a maintainer that I haven't thought about hooking up because of how often the car gets driven

what i-Level is on your vehicle? version 11/2022.56 specifically addressed vehicles that could be affected by excessive 12V battery draw

[E91toG05]

Update?

[viperdoc]

Originally Posted by E91toG05

Update?

Hey all. So dealer called and confirmed it was the 12V that died. So, easy fix and definitely a quirk of the vehicle I hadn’t really thought of before. I figured with that huge battery that was charged why not have enough juice to start it up?? Certainly ignorance on my part. I guess next time the whole car dies I need to remember what I used to do in the old days when you have no power…. Try to jump it first!

[DwainA]

I've had my 2021 45e for almost 3 years now. It has 61,000+ miles on it and has been rock solid until now. Luckily I bought the BMW extended warranty knowing that I'll be keeping this car for a LONG time.

Just before leaving on a week long trip, I noticed that my BMW card and iPhone stopped opening my door. I thought it was a software issue and ignored it. When I pulled into the long term parking kiosk my driver window wouldn't roll down. I made a mental note to schedule BMW service when I returned. Turned out I didn't need that mental note because when I came back a week after my "2021 45e completely died"!!!

My BMW dealer got the car towed to them on Nov. 9th (getting it towed is another post) and I got the car back on Nov. 28. It turned out that the HV Battery SME had open contactors and had to be replaced. So did the two 12V batteries since they were completely drained and could not be recharged. My Hendricks BMW dealer did a great job of communicating with me and with BMW. They got me an X5 loaner and the experience didn't cost me a cent.

For other 45e owners - Watch out for minor electrical failures because they MAY be an indicator that the 12V batteries are failing. My car gave no warning that the 12V batteries were not being charged by the High Voltage batteries. If those batteries get too depleted they cannot be recharged, the car cannot be jumped and nothing works.

I was lucky that I had this failure near civilization. I drive this 45e with All Terrain tires and get off the beaten path at times. I can't imagine having this no warning failure 300 miles away from a BMW dealer or on a gravel road somewhere.

The car had to be dragged out of a covered parking spot with cars on each side and in an aisle that was just 2 car lengths wide. Luckily I got a tow driver that knew how to maneuver in that space and had skid pads for an AWD vehicle. It wasn't pretty, but it worked. I'm also glad that I have a rear tow hitch. I'm sure we would have broke something getting it out of the parking space otherwise.

[eelnoraa]

Originally Posted by DwainA

I've had my 2021 45e for almost 3 years now. It has 61,000+ miles on it and has been rock solid until now. Luckily I bought the BMW extended warranty knowing that I'll be keeping this car for a LONG time.

Just before leaving on a week long trip, I noticed that my BMW card and iPhone stopped opening my door. I thought it was a software issue and ignored it. When I pulled into the long term parking kiosk my driver window wouldn't roll down. I made a mental note to schedule BMW service when I returned. Turned out I didn't need that mental note because when I came back a week after my "2021 45e completely died"!!!

My BMW dealer got the car towed to them on Nov. 9th (getting it towed is another post) and I got the car back on Nov. 28. It turned out that the HV Battery SME had open contactors and had to be replaced. So did the two 12V batteries since they were completely drained and could not be recharged. My Hendricks BMW dealer did a great job of communicating with me and with BMW. They got me an X5 loaner and the experience didn't cost me a cent.

For other 45e owners - Watch out for minor electrical failures because they MAY be an indicator that the 12V batteries are failing. My car gave no warning that the 12V batteries were not being charged by the High Voltage batteries. If those batteries get too depleted they cannot be recharged, the car cannot be jumped and nothing works.

I was lucky that I had this failure near civilization. I drive this 45e with All Terrain tires and get off the beaten path at times. I can't imagine having this no warning failure 300 miles away from a BMW dealer or on a gravel road somewhere.

The car had to be dragged out of a covered parking spot with cars on each side and in an aisle that was just 2 car lengths wide. Luckily I got a tow driver that knew how to maneuver in that space and had skid pads for an AWD vehicle. It wasn't pretty, but it worked. I'm also glad that I have a rear tow hitch. I'm sure we would have broke something getting it out of the parking space otherwise.

May I ask why jumping the 12V wont work? once the jumper wake up the car, would the DC-DC start to take over and supply 12V? Not that I plan not not replace the battery, but in a pinch, I wonder if I can start, get home or dealer.

[philooo]

I had the same issue since then I carry a lithium ion battery jumper. when my car died, the lithium jumper allower me to start the engine and drive in limp mode.. not fun but made it back home

[jad03060]

Even if the HVB has a charge, if your 12vdc power won't turn any of the other electronics on, the vehicle is bricked. THe DC-DC converter requires the computer to work, at least initially, for the vehicle to operate. Once it does run, if the HVB has some capacity, between the EV motor being driven as an alternator, you should be able to keep it running because that power, through the HVB, and the DC-DC converter should be able to keep it running.

Now, if the HV contactor can't be closed, no 12vdc, and the EV motor's output can't get to the batteries, so things get much more problematic. There might be a backup path, so I don't know.

On the i3, if the 12vdc battery was low beyond a certain point, there was a trickle charge path to feed it if it was plugged into the EVSE...even though it was an EV, it still relied on 12vdc to run the computers, so seems to be what BMW is doing with them and their PHEVs. The i3 wouldn't charge the HVB until all of the computers could run off of the 12vdc system, so was a planned backup path they engineered in.

[travwill]

In all car forums I read endless posts about 12v failures. Causes tons of errors and usually dead cars. A technology from 70 years ago, when they upped from 6 volts. Now cars have tons of electronics.

Tesla is prob the leader here, new 48v architecture in their Cyber truck is first of its kind. Others will follow in time with it and better batteries as well.

[jad03060]

There's a huge history of 12vdc devices so any wholesale change to another voltage will take time. One advantage of higher voltages is that you can get the same power through smaller wires. The service industry would need a lot of new test tools and learning to deal with higher voltage things not counting all of the suppliers having to retool to make 48vdc devices versus 12vdc ones. BMW has dipped their toes into this with the mild hybrid stuff that relies on a 48vdc lithium battery. More will come, but it will take time. In the meantime, there can be some commonality across their product line with the 12vdc stuff.

[swainbmw]

Originally Posted by travwill

In all car forums I read endless posts about 12v failures. Causes tons of errors and usually dead cars. A technology from 70 years ago, when they upped from 6 volts. Now cars have tons of electronics.

Tesla is prob the leader here, new 48v architecture in their Cyber truck is first of its kind. Others will follow in time with it and better batteries as well.

The mild hybrid X5 is 48 V mine is a 2022

[DwainA]

Originally Posted by eelnoraa

May I ask why jumping the 12V wont work? once the jumper wake up the car, would the DC-DC start to take over and supply 12V? Not that I plan not not replace the battery, but in a pinch, I wonder if I can start, get home or dealer.

I travel with a battery pack just for that purpose. It would very briefly light things up, but die immediately. It didn’t give me enough time to get the car into neutral so I could roll it out of the space.

I think the key lesson here is that the AGM 12V batteries in at least the 45e can get depleted to a level where they won’t take a normal jump or recharge. It also appears that there are no warnings or displayed error codes to let the driver know of an impending failure. With a standard lead acid battery / alternator combo you have a good probability that a jump will let you limp to a place to recharge or replace the battery. NOT in the 45e’s case!

[jad03060]

If you could borrow a 12vdc battery charger, or solicit help from a friend with a long enough set of jumper cables, you might get it to come on enough to get it out of the garage.

While the transmission can be forced into neutral, it's not an easy mechanical task as it is done from underneath. Some brands using this transmission have made it easier, but BMW has not.