[Renzm]

Originally Posted by tcbmhell

This's what it says on G05 manual.

From the G20 manual:



I assume just a bit of different language between European and US manual wording.

[Teutonic]

Any updates from you guys with this issue?
I am also trying to trickle charge my AGM baterry and get same battery management error and the engine bay noises

[TurtleBoy]

Originally Posted by Teutonic

Any updates from you guys with this issue?
I am also trying to trickle charge my AGM baterry and get same battery management error and the engine bay noises

Engine bay noises are normal. There has been a big discussion of this on the G05 forum also. Quite a few folks have been successful in the charging/tending. Here are the steps one of your fellow countrymen posted and it seems to be working. These are the ones I will follow when I get my M340i.

I have successfully charged battery three times (MY21 40i) using the steps below:

1. Start the vehicle and turn off, then turn off the iDrive manually by pressing the volume knob a few seconds. This ensures iDrive go into sleep mode (also known as idle state, see details on this at the end of the post). This seems to be the trick. If you want to be extra careful then use Digital Key Card to do the steps. It removes another variable (comfort access proximity sensors used by key fobs).

2. Open door, exit car, open bonnet, and close door (don't lock yet). Keep the bonnet open until charging is complete (THIS IS A MUST), two U-shaped bonnet latches should not go into the sockets (this is how vehicle knows if the bonnet remains open or not).

3. Connect charger cables in this sequence: positive > negative > charger power.

4. Lock the car. Don't open doors while the car being charged, this might cause charging/battery related error codes being displayed on iDrive later. Note that you might hear a few actuator motors makes brief noises between engine bay and dashboard as if those are trying to open/close something, this is normal. A few LEDs on buttons around driver seat will continue to be illuminated for about 15 minutes and turn off automatically after a while, this is also normal.

5. Move away from the car and don't do anything that might wake up the iDrive.

6. When battery is fully charged disconnect the cables in reverse order: charger power > negative > positive. Close hood/bonnet.

Depending on the charger type and battery charge state it might take long, I usually keep it going overnight.

[Teutonic]

Originally Posted by TurtleBoy

Engine bay noises are normal. There has been a big discussion of this on the G05 forum also. Quite a few folks have been successful in the charging/tending. Here are the steps one of your fellow countrymen posted and it seems to be working. These are the ones I will follow when I get my M340i.

I have successfully charged battery three times (MY21 40i) using the steps below:

1. Start the vehicle and turn off, then turn off the iDrive manually by pressing the volume knob a few seconds. This ensures iDrive go into sleep mode (also known as idle state, see details on this at the end of the post). This seems to be the trick. If you want to be extra careful then use Digital Key Card to do the steps. It removes another variable (comfort access proximity sensors used by key fobs).

2. Open door, exit car, open bonnet, and close door (don't lock yet). Keep the bonnet open until charging is complete (THIS IS A MUST), two U-shaped bonnet latches should not go into the sockets (this is how vehicle knows if the bonnet remains open or not).

3. Connect charger cables in this sequence: positive > negative > charger power.

4. Lock the car. Don't open doors while the car being charged, this might cause charging/battery related error codes being displayed on iDrive later. Note that you might hear a few actuator motors makes brief noises between engine bay and dashboard as if those are trying to open/close something, this is normal. A few LEDs on buttons around driver seat will continue to be illuminated for about 15 minutes and turn off automatically after a while, this is also normal.

5. Move away from the car and don't do anything that might wake up the iDrive.

6. When battery is fully charged disconnect the cables in reverse order: charger power > negative > positive. Close hood/bonnet.

Depending on the charger type and battery charge state it might take long, I usually keep it going overnight.

Good evening.
Thank you kindly for your reply. I will try your suggestions.

[covinsky]

Update, our 2021 M340i end up sitting in our garage for over three months with no battery tender and the car started no problem. I guess these new mild hybrids do not need a battery tender?

[ohniner]

Have been trying to get an answer from two dealers, BMW genius when finally the shop foreman from United BMW Atlanta where we bought our 2022 M340i responded by voice and email. This was his written response:

Here is the information for the charging procedure. Ill give you a call to discuss.

External charging of the vehicle is still performed via the 12V jump start terminal in the engine compartment. Primarily, this is intended to charge the 12V battery. When a threshold of approximately 50% state of charge of the 12 V battery is exceeded, the 48 volt battery is likewise charged. To this end the system is powered up after a defined charging voltage has been exceeded and placed in boost mode. The lithium-ion battery can be externally charged in the driving condition residing, stationary functions and PAD. External charging only functions if the hood has been detected as being open. With the vehicle in sleep mode the IBS detects the external battery charge and wakes the vehicle up, whereupon the 48-volt electrical system is powered up. External charging is terminated when the charging voltage drops again or the 48 volt battery is fully charged.

What was not addressed is wether our AGM chargers (non Li) can charge the 48v battery which may be the issue. I'm digging further into this. Also was told that BMW uses only shop specific chargers that may sense AGM or Li and can cycle backhand forth.

Anyone have any other updates?

[Teutonic]

Originally Posted by TurtleBoy

Engine bay noises are normal. There has been a big discussion of this on the G05 forum also. Quite a few folks have been successful in the charging/tending. Here are the steps one of your fellow countrymen posted and it seems to be working. These are the ones I will follow when I get my M340i.

I have successfully charged battery three times (MY21 40i) using the steps below:

1. Start the vehicle and turn off, then turn off the iDrive manually by pressing the volume knob a few seconds. This ensures iDrive go into sleep mode (also known as idle state, see details on this at the end of the post). This seems to be the trick. If you want to be extra careful then use Digital Key Card to do the steps. It removes another variable (comfort access proximity sensors used by key fobs).

2. Open door, exit car, open bonnet, and close door (don't lock yet). Keep the bonnet open until charging is complete (THIS IS A MUST), two U-shaped bonnet latches should not go into the sockets (this is how vehicle knows if the bonnet remains open or not).

3. Connect charger cables in this sequence: positive > negative > charger power.

4. Lock the car. Don't open doors while the car being charged, this might cause charging/battery related error codes being displayed on iDrive later. Note that you might hear a few actuator motors makes brief noises between engine bay and dashboard as if those are trying to open/close something, this is normal. A few LEDs on buttons around driver seat will continue to be illuminated for about 15 minutes and turn off automatically after a while, this is also normal.

5. Move away from the car and don't do anything that might wake up the iDrive.

6. When battery is fully charged disconnect the cables in reverse order: charger power > negative > positive. Close hood/bonnet.

Depending on the charger type and battery charge state it might take long, I usually keep it going overnight.

Doesnt work

[MBM340]

Wish someone who works at BMW could give us the straight answer here....anyone home at BMW who has the correct answer?
Thanks,
MB

[zazzau]

Originally Posted by MBM340

Wish someone who works at BMW could give us the straight answer here....anyone home at BMW who has the correct answer?
Thanks,
MB

I am able to charge my battery with ZERO issues. The last time I charged was a few days ago after the car had been garaged for 5 weeks - took probably about 5 hours to fully charge. I use this charger - a bit pricey but gets the job done. I have a Mild Hybrid (M340i MY21.) I managed to get a good deal at the time I bought mine so perhaps you might want to shop around.

https://www.amazon.com/dp/B0045F3SGY..._Y2FRxkkj47qcN

[G22b58]

@zazzau, so the high current capability of that charger might do the trick if you don't use the special "iDrive OFF"-procedure?
Or did you do anything special other than keeping the hood open?

[Aziego]

Unless there is parasitic drain on the 48V lithium battery (I don't see why there would be when parked) I would not worry about it. From my experience with RC vehicles, it is not good to store lithium batteries fully charged, it actually reduces the lifespan. Lithium batteries have low internal resistance so they do not self discharge like the other batteries. When I store lipo batteries for my RC vehicles I always discharge to 50%.

[zazzau]

A relevant post here to add to the conversation:

https://g07.bimmerpost.com/forums/sh....php?t=1781421

[G22b58]

@zazzau, Thanks for the G07 link. In your successful charging, did you have the hood closed or open?
I wonder, if I only want to charge the 12V battery, if it is essential to have the hood closed already when connecting power to the charger?

[zazzau]

Originally Posted by G22b58

@zazzau, Thanks for the G07 link. In your successful charging, did you have the hood closed or open?
I wonder, if I only want to charge the 12V battery, if it is essential to have the hood closed already when connecting power to the charger?

Connected the charger and closed the hood.

[cszekl]

Friends, I just tender charge my battery in the trunk like I have done several of my other BMW's with no issues. I contacted both of my local BMW Dealerships and they are both in agreement things will be fine. I store my M340 for about 5 months out of the year with carpet squares under tires with a slight psi increase in each tire. No issues. Plus the Lithium battery under the hood won't loose the charge over four to five months.

[zazzau]

Originally Posted by cszekl

Friends, I just tender charge my battery in the truck like I have done several of my other BMW's with no issues. I contacted both of my local BMW Dealerships and they are both in agreement things will be fine. I store my M340 for about 5 months out of the year with carpet squares under tires with a slight psi increase in each tire. No issues. Plus the Lithium battery under the hood won't loose the charge over four to five months.

You mean to say you charge the 12V battery in the trunk directly ? By "truck" I suppose you meant to say trunk. Where do you plug the battery charger in the trunk? Personally I'd stick with charging from the terminal in the hood since that already works for me.

[TurtleBoy]

Originally Posted by zazzau

You mean to say you charge the 12V battery in the trunk directly ? By "truck" I suppose you meant to say trunk. Where do you plug the battery charger in the trunk? Personally I'd stick with charging from the terminal in the hood since that already works for me.

Yes, stick to using the terminals in the engine compartment for charging. As stated in the manual and by dealers, you should not connect directly to the battery when charging.

[cszekl]

Originally Posted by TurtleBoy

Yes, stick to using the terminals in the engine compartment for charging. As stated in the manual and by dealers, you should not connect directly to the battery when charging.

I have read that warning in the manual also. That’s why I asked the dealership advisor. The positive and negative Terminals under the hood are the same terminals that are on the battery in the trunk under the carpet. So, the
Terminals under the hood are an extension to the battery in the trunk do to design location. No issues can happen to the 12 volt system when using a Quality battery Tender and pigtail off of the battery.
I made sure my dealership approved of my set up. I think maybe we over thinking things here. Maybe a BMW tech could chime in on the topic.

[TurtleBoy]

Originally Posted by cszekl

I have read that warning in the manual also. That’s why I asked the dealership advisor. The positive and negative Terminals under the hood are the same terminals that are on the battery in the trunk under the carpet. So, the
Terminals under the hood are an extension to the battery in the trunk do to design location. No issues can happen to the 12 volt system when using a Quality battery Tender and pigtail off of the battery.
I made sure my dealership approved of my set up. I think maybe we over thinking things here.

You obviously can do what you want, just wanted to make sure others are aware of the proper procedure. Your dealer is the first I heard of saying connecting directly to the battery was okay.

[cszekl]

Originally Posted by TurtleBoy

You obviously can do what you want, just wanted to make sure others are aware of the proper procedure. Your dealer is the first I heard of saying connecting directly to the battery was okay.

Thanks I wouldn’t want to cause damage
Maybe a BMW tech could chime in. In words that could be understood by a layman. What I want to know is the forty eight volt system completely separate from the 12 V system? All the Hybrids that I know are separate systems completely.

[TurtleBoy]

Originally Posted by cszekl

Thanks I wouldn’t want to cause damage
Maybe a BMW tech could chime in.

The terminals under the hood are not a direct connection to the battery since there is a connection to the IBS. If you don't use the terminals under the hood then the charging may not be registered by the IBS and in some circumstances you will have unwanted results such as not being able to start the vehicle. Perhaps something recently changed so ask your service advisor why it is now acceptable to connect directly to the battery for charging.

[zazzau]

Originally Posted by cszekl

I have read that warning in the manual also. That's why I asked the dealership advisor. The positive and negative Terminals under the hood are the same terminals that are on the battery in the trunk under the carpet. So, the
Terminals under the hood are an extension to the battery in the trunk do to design location. No issues can happen to the 12 volt system when using a Quality battery Tender and pigtail off of the battery.
I made sure my dealership approved of my set up. I think maybe we over thinking things here. Maybe a BMW tech could chime in on the topic.

I guess the question is why do you opt for the trunk rather than the terminal under the hood? Just curious. From your post it sounds like it's just based on old habits from previous cars you've owned.