[Teutonic]

Originally Posted by JSaid

Sorry for the delay here let me explain my experience a little better.

So with the noco 25, I plugged it in to the car after leaving it unlocked, hood open and waiting ~5-10 minutes for all the interior lights to shut off. I did check the battery level in idrive before starting and it was at 2 bars.

After plugging it in the first thing I noticed was the familiar clicking noise from the ctek in the beginning, but it only happened once. It did not continuously occur as with the ctek. I then left the garage for a little. Upon coming back ~45 minutes later. The charger was on the last stage (blinking green) and I decided to hang around with it for a little. Shortly after I heard a new sound (like switches/relays flicking) again only once. After waiting about ~5-10 minutes I left the garage and came back another 20 or so minutes later.

At that point I disconnected the charger to check on the car(still on last stage of charging) got in and checked idrive waking up the car. The idrive battery level was on four bars now as opposed to two before I started.I then let the car go back to sleep and finish charging until full.

Started up the car and all seems fine. I scanned for codes as well and didn't find any except a few low battery warnings and some small driver assistance errors (from when I swapped my mirror caps disconnecting the glass, unrelated).

To double check I cleared all the codes about a week later and retried charging. No codes showed up (however I noticed a code for a WLAN failure , I think it was on bmws side. The apps in idrive weren't loading for a few days and then it just started working again. Probably servers down or something). Maybe I can try recreating the battery management error and see if that throws anything.

Since then I also took it in to the dealer for an oil change and figured I'd have them check the battery as well. I mentioned the sounds and prior errors and they ended up doing a full inspection of the 48v battery as well as the rest of the car and found nothing wrong with it. At this point I'm just summing it up to the 48v system makes weird sounds lol they must be a normal part of the charging system. if anything goes wrong later I can point out my previous dealer visit and hopefully it's an easy warranty claim but I think it's all good. I'll continue to scan for codes occasionally to see if anything comes up

I don't leave the car sitting for too long at a time it's mostly if the roads are bad(New York) so I don't think I'll run into this again with leaving the car unlocked in the garage. Im pretty sure it was the security system draining the battery quick. You can also monitor all of the 48v battery performance metrics while you drive with BimmerLink so maybe I'll give that a shot too

Thank you for your reply.

Since it works in your case, can you please let me know, the Noco was set on 12V AGM, correct?

Also, can you please try to lock the car and connect and see if it makes a difference? What about connect and lock the car after?

Mine is in a common parking now and can not leave it unlocked.
Thank you so much!

[JSaid]

Originally Posted by Teutonic

Thank you for your reply.

Since it works in your case, can you please let me know, the Noco was set on 12V AGM, correct?

Also, can you please try to lock the car and connect and see if it makes a difference? What about connect and lock the car after?

Mine is in a common parking now and can not leave it unlocked.
Thank you so much!

Yeah I was on 12V AGM. Sure I'll give it a shot today after work and let you know what happens!

[Teutonic]

Originally Posted by JSaid

Yeah I was on 12V AGM. Sure I'll give it a shot today after work and let you know what happens!

So to reiterate the questions and put more questions:

1. Hood is open during charging?
2. Car locked -> after complete shut off, does it charge?
3. Car unlocked -> after complete shut off,does it charge?
4. How you check the battery level in idrive? Start the engine and go to “energy flow”? Or you just go in the idrive without starting the engine? Or is another way to check it which I am not familiar with…?

LOL, I drive you nuts, but I apreciate your help as this way maybe we can figure out what the heck is going on…
Thank you!

PS
What do you use for scanning codes ?

[JSaid]

Originally Posted by Teutonic

So to reiterate the questions and put more questions:

1. Hood is open during charging?
2. Car locked -> after complete shut off, does it charge?
3. Car unlocked -> after complete shut off,does it charge?
4. How you check the battery level in idrive? Start the engine and go to “energy flow”? Or you just go in the idrive without starting the engine? Or is another way to check it which I am not familiar with…?

LOL, I drive you nuts, but I apreciate your help as this way maybe we can figure out what the heck is going on…
Thank you!

PS
What do you use for scanning codes ?

Lol no worries happy to help,

1) yes, hood is open

2) car locked, just tested recently and this one was interesting. I plugged it in with the car locked at first after waiting for what I thought was sleep mode and noticed the charger stuck on red such as you did(and similar to ctek). after ~5 minutes I unplugged and waited ~10 minutes to reconnect and then it started charging normally the same way as when unlocked. Went to green. My guess on this one is that maybe it's related to sleep mode rather than locked/unlocked. I also moved the key away from the car further so if it's too close maybe that prevents sleep mode completely? I also may have not waited long enough? Little confused on this one not too sure what happened here, no error codes or anything. I took it for a drive and all seems normal again. It's pretty annoying how much weirdness we have to deal with just for a simple charge lol. Maybe give it a shot by popping the hood, locking the car, wait 10-15 minutes and move the keys farther away? Or better yet keep the keys away and just use the app to lock/unlock. Just typing that last part made me think, yeah we really shouldn't have to do all this just to charge our new BMWs hahah

3) yea, when the car was unlocked, and left to go into sleep, it worked fine the first time.

4) I checked the battery by just going into idrive and checking energy flow. Pretty sure I didn't start the car. You can also check the exact percentages of both the 12v and 48v through bimmerlink and the scan tool. Since it seems like the car has to be in sleep to charge I don't think there's anyway to monitor progress live except through the external battery (someone correct me if they know a way )

For scanning I have the OBDLink MX+. It's great for coding with BimmerCode too

Scan tool: https://www.amazon.com/OBDLink-Bluet...76039461&psc=1

Bimmerlink: https://apps.apple.com/us/app/bimmer...i/id1065360416

One other idea I had for you, would it be possible to leave the car unlocked just until the charge gets to full (maybe like ~2-3 hours) and then lock it while it's in the final maintenance/optimization step? I wonder if that would work, you can probably hit the 5amp button as well to lower the power at that point(or maybe even switch back to the ctek)?

Hope this helps and we can finally get to the bottom of how this really works lol. Let me know if I can help in any other way

[bavarianride]

Originally Posted by JSaid

My guess on this one is that maybe it's related to sleep mode rather than locked/unlocked. I also moved the key away from the car further so if it's too close maybe that prevents sleep mode completely? I also may have not waited long enough?

I think the quickest way to get the car into sleep mode is:

1. open hood(get ready to charge)
2. close door
3. lock (alarm beeps once if enabled)
4. unlock (alarm beeps twice if enabled)

iDrive should be blank(i.e. sleep mode) after step#4.

[Teutonic]

Originally Posted by JSaid

Lol no worries happy to help,

1) yes, hood is open

2) car locked, just tested recently and this one was interesting. I plugged it in with the car locked at first after waiting for what I thought was sleep mode and noticed the charger stuck on red such as you did(and similar to ctek). after ~5 minutes I unplugged and waited ~10 minutes to reconnect and then it started charging normally the same way as when unlocked. Went to green. My guess on this one is that maybe it's related to sleep mode rather than locked/unlocked. I also moved the key away from the car further so if it's too close maybe that prevents sleep mode completely? I also may have not waited long enough? Little confused on this one not too sure what happened here, no error codes or anything. I took it for a drive and all seems normal again. It's pretty annoying how much weirdness we have to deal with just for a simple charge lol. Maybe give it a shot by popping the hood, locking the car, wait 10-15 minutes and move the keys farther away? Or better yet keep the keys away and just use the app to lock/unlock. Just typing that last part made me think, yeah we really shouldn't have to do all this just to charge our new BMWs hahah

3) yea, when the car was unlocked, and left to go into sleep, it worked fine the first time.

4) I checked the battery by just going into idrive and checking energy flow. Pretty sure I didn't start the car. You can also check the exact percentages of both the 12v and 48v through bimmerlink and the scan tool. Since it seems like the car has to be in sleep to charge I don't think there's anyway to monitor progress live except through the external battery (someone correct me if they know a way )

For scanning I have the OBDLink MX+. It's great for coding with BimmerCode too

Scan tool: https://www.amazon.com/OBDLink-Bluet...76039461&psc=1

Bimmerlink: https://apps.apple.com/us/app/bimmer...i/id1065360416

One other idea I had for you, would it be possible to leave the car unlocked just until the charge gets to full (maybe like ~2-3 hours) and then lock it while it's in the final maintenance/optimization step? I wonder if that would work, you can probably hit the 5amp button as well to lower the power at that point(or maybe even switch back to the ctek)?

Hope this helps and we can finally get to the bottom of how this really works lol. Let me know if I can help in any other way

Thank you for
your reply. I will try again. One more thing: can you please check if with the doors closed you can hear the 48V relay clicking, hence the Noco charges the 48V battery please?
Thanks!

[covinsky]

Still trying to understand why a battery tender will NOT work with my 2021 M340I. Spoke with BMW shop foreman at local dealership today. He stated I need to have a 30 amp digital charger ($600 - $700) for my M340I. Anything less will cause the 48 volt relays to constantly make noise every couple of minutes. I even disconnected the 48 volt battery connector G14*1B per service info bulletin SIB 61 01 21 by BMW with no success. I can’t believe BMW still sells their own brand battery chargers at 4 and 5 amps and haven’t had numerous complaints. There has to be many other that let their cars sit for months not driven either in or out of season. So here I go letting this car sit for the next 4 months with no trickle charger waiting to pay for a dead 12 volt battery $500 and a dead 48 volt battery $1500!!! There has to be a reasonable solution.

[TurtleBoy]

I tried a test the other day and finally successfully charged the battery. My steps were as follows:

1. Unlock with key card
2. Open the hood
3. Close Hood Open message
4. Push and held volume button to turn off iDrive
5. Closed but not locked the door
6. Hooked up charger to commence charging

I did not have the constant noise that I had on previous attempts. I used a Schumacher SC1281 as I had before.

[bavarianride]

A friend had issues with charging his M340i, but recently he succeeded to charge with a CTEK 4.3 by making sure the iDrive went blank, and kept the hood opened and car unlocked, before hooking up charger.

My gut feel is that iDrive completely off is an important factor.

Originally Posted by covinsky

Still trying to understand why a battery tender will NOT work with my 2021 M340I. Spoke with BMW shop foreman at local dealership today. He stated I need to have a 30 amp digital charger ($600 - $700) for my M340I. Anything less will cause the 48 volt relays to constantly make noise every couple of minutes. I even disconnected the 48 volt battery connector G14*1B per service info bulletin SIB 61 01 21 by BMW with no success. I can’t believe BMW still sells their own brand battery chargers at 4 and 5 amps and haven’t had numerous complaints. There has to be many other that let their cars sit for months not driven either in or out of season. So here I go letting this car sit for the next 4 months with no trickle charger waiting to pay for a dead 12 volt battery $500 and a dead 48 volt battery $1500!!! There has to be a reasonable solution.

[turbobeagle]

Thanks to those that reported their trials. Just adding mine to the mix.

- 2023 X3 M40i. Just a couple days old.
- Ctek 5 amp charger hit green (stage 7) in about 3 hours.
- The killwatt reports only 140 Wh of energy transmitted. I guess the battery was pretty full.
- IDrive manually shut down, locked car, hood wide open.
- The car was making the clicking/buzzing noises frequently the entire time.

[JSaid]

Hey all,

Just wanted to post an update here. So I went to try the noco 25 again and this time I got a different behavior. Didn't seem to be working with clicking consistent with the ctek mxs5. It's inconsistent, noticed the charging stages go backwards at a certain point. The first time it went to the final "green" stage but never fully completed, had to disconnect and take the car out.

After some more research I returned the noco and bought the ctek pro25s. This is the first charger that has had no issues and went to float (final maintenance stage)no problem. The only sound was an initial single click of what I think is the 48v battery relays to engage it, no sounds after that.

Looks like the ctek pro25s is the only one that fully works (at least for me). For those curious, normal mode is for normal lead acid and agm batteries. Oh drawback is the cost, I found it the cheapest on ecstuning. I think it's pretty safe to say the clicking is due to too low ampage for charging the 48v which causes the relays to cycle every minute or so. Hope this helps anyone still having issues

[GaryGK]

I have a 2021 M440i and just purchased a Nexpeak NC201 Intelligent charger. I went for a short drive this morning, not long enough to fully re-charge the battery to see if the charger works. My battery was at 12.9 volts when I connected the charger and it was fully charged in 15 minutes. So I'm not sure what the problem is with the people on here who are having problems charging their battery with a charger. When I plugged in the charger the car made the same strange noises it makes when I shut it off. Perhaps the chargers you guys are using just aren't compatible for the AGM battery. It's strange BMW can't give a straight answer on this issue.

[Tommygunn]

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.

M340d 2021 model
After reading all your posts on this thread I plugged in my AA car battery charger to charge up the battery as my car is currently not being driven.
I opened the door, switched off the iDrive and then connected the charger and locked the car but left the bonnet open.
I thought everything was fine but after hanging around the car ,I noticed that there were clicking noises every 15 minutes and the hazard warning switch along with the auto lights switch would light up and stay lit for a couple of minutes before going off. This would repeat again after approximately 15 minutes.
I then disconnected the charger and unlocked the car, opened the door, switched off the iDrive , closed the door without locking it and reconnected the charger.
The same thing happened again after every 15 minutes.
The clicking noises with the doors open or locked happened every 15 minutes with no noises in between.

I will wait and see if the battery goes to 100% and will update when that happens.
Just don't understand what the car is trying to do when the clicking noises occur
Is anyone any wiser why it's happening ?

[1QuikWS6]

I use the CTek MXS 5.0 on both my 435 & M440 48V MH with no issues

[Tommygunn]

I left the charger on overnight but gave up the following day as I feel the clicking noises mean something is waking up and obviously using the battery and negating the work the charger is doing.

I had a warning on the iDrive saying drive the vehicle due to the battery drain from the regular waking up .

Has anyone used the official BMW charger and if so do you still get the clicking noises with that ?

[MilesToEmpty]

Ive been watching the hybrid battery in my 22 and notice its usually about 2 bars full when Im driving. Ive only succeeded in filling it entirely once and that was using engine braking/braking on a really long mountain.

Does the battery regen through braking on these?

And why are people trying to charge the 48v hybrid system when the car is sitting? The only other cars I had that were a hybrid were a Prius and a Crosstrek, and the hybrid system didnt need any external charging done to it ever.

[zazzau]

Originally Posted by MilesToEmpty

And why are people trying to charge the 48v hybrid system when the car is sitting?

You can't charge the 48v directly; the charger tops off the 12v battery and the PCU in turn charges the 48v.

But to the point of your question: Americans are obseesed with trickle charging that's why.

[MilesToEmpty]

Originally Posted by zazzau

You can't charge the 48v directly; the charger tops off the 12v battery and the PCU in turn charges the 48v.

But to the point of your question: Americans are obseesed with trickle charging that's why.

Hah figured... I only run one on my old Subaru since it gets driven once a month and i keep killing the battery.

[anandn]

Haven’t updated here in a while. As I mentioned before, I’ve had no issues charging the 12 starter battery in my 2023 440i convertible using a CTEK MXS charger with hood open. I left the car in Florida for 2 months while I was in NH. Despite idrive being off, the car was making clicking and whirring sounds but to no detriment.

Talked to the service advisor at Braman BMW in Jupiter about the sounds the car was making while being charged when they were replacing a failed TCM. He did not think that was a concern. Also told me that the 48v lithium ion battery could be disconnected by turning car off and then pressing the start/ button three times rapidly. The car enters diagnostic mode. The hood can then be closed with the 12 v charger. He also didn’t think this was necessary to do that when using a CTEK charger.

FYI. Self-professed gurus on this forum can comment or make their conclusions. I don’t have trouble charging my car and plan to leave it in FL with a charger when I am back north for the summer. Good luck. ����

[sjb993]

FYI. Self-professed gurus on this forum can comment or make their conclusions. I don’t have trouble charging my car and plan to leave it in FL with a charger when I am back north for the summer. Good luck. ����

I'm not sure if this document has been referenced before in this thread, but if not here's what the BMW gurus say about charging MHT cars.

[M340_gn.pol]

i had the same problem with the bmw ctek charger.
Only click sounds and the charger was remaining in stage 3.
And when it was time to drive the car i had the battery managment message on idrive.
I bought ctek 25pro s and everything works great now.

I d like to ask something more.
My car was connected in ctek 25 pro s charger and it was in final stage where keeps the battery full charged.
I disconnected it and i drove for 3 km.
When i came back and connected the charger again, it needed around 60 minutes or more to take the battery again in last stage.
Is it normal ?

[HighlandPete]

Originally Posted by M340_gn.pol

My car was connected in ctek 25 pro s charger and it was in final stage where keeps the battery full charged.
I disconnected it and i drove for 3 km.
When i came back and connected the charger again, it needed around 60 minutes or more to take the battery again in last stage.
Is it normal ?

Keep in mind the intelligent alternator control won't be charging, to 'top up', if the battery is at a high SoC. Following the 12 volt efficient dynamics strategy, battery capacity is required for over-run charging.

Not sure of the exact operating strategy for the mild hybrid, but you still need battery capacity for regeneration charging.