[VINCER0]

I've recently been looking at my 2021 M340i xDrive's battery charging menu screen and I can't seem to charge it past 2 "bars" for a longer length of time.

I realize the 48v mild hybrid system decouples the alternator during acceleration, and only charges it when coasting or braking...the most I've been able to charge it was up to 4/5 bars in sports mode by coasting on the highway but then it quickly went back down to 2 bars after city driving in sports mode for a few minutes.

Also shutting off the car and starting it made the car's lithium battery go to one bar. I thought the starter used the 12v agm so why would the lithium battery run down after an engine start up?

[thakid22]

The hybrid battery is used to power vehicle accessories as well. Headlights, radio, climate control, instrument panel, and various ecu's will all draw power from the lithium battery at rest (even when the engine is off).

Coasting does charge the hybrid battery, but to get maximum charging you need to apply moderate to firm braking pressure. Brisk stopping or slowing charges the battery pretty quickly. In normal traffic at a nice pace, the hybrid battery may never reach full charge. A brisk drive through a neighborhood with lots of stop signs in close proximity charges the battery fully, especially if you wait until the last moment to brake for the stop signs thus braking a little harder than normal.

That will top the battery off and it will stay in the upper range of full for a while. But if you just have to have it full all of the time you will have to repeat the procedure periodically. The system seems to love stop and go driving, or Moreno, the braking that accompanies it.

Alternatively, you can find an empty road at night and do a couple of hard braking/soft acceleration cycles at medium speeds and it will get you up to full relatively quickly. (Make sure no one is behind you to run into you though).

[Mason Hatcher]

So you can't just drive the car normally? Note to self: avoid hybrids

[thakid22]

Originally Posted by Mason Hatcher

So you can't just drive the car normally? Note to self: avoid hybrids

You can indeed drive the car normally. Do not avoid the hybrid, it's great!
I had a 2020 M340i for a few days, but BMW bought that car back as it was broken.
I replaced it with an identical 2021 M340i that included the hybrid system.

The hybrid is more responsive, gets better gas mileage, revs more freely, and the auto stop/start is smoother. It also comes with an eBoost mode that provides additional power during hard acceleration. All wins! There have been no negative effects regarding the addition of the hybrid system. In fact, it has opened the door to me toying with the idea of a fully electric vehicle next time around (Porsche Taycan or BMW 440iGC M50i).

The hybrid system fully functions on its own without intervention (or special process) from the driver. The procedure I detailed in the previous post is simply to aid OCD types who desire to see the battery at full charge at all/most times. But no, you don't have to drive it in any special way for it to work as designed and intended.

[mslevin]

I agree, the hybrid is great. I’ve seen mine full or near full in traffic or when driving quite quickly (on track or backroads).

I don’t think there’s really any need to fully charge it, if that’s the concern. I’ve never noticed any difference in performance with the battery full, empty, medium, etc.

[user1811]

I guess if the battery was kept fully charged at all times there wouldn't be anywhere for the recuperated energy to be stored. So it'd be wasted.

[gnolivos]

Where is this battery menu / screen that there OP speaks of? I can't find it.

[HighlandPete]

Originally Posted by user1811

I guess if the battery was kept fully charged at all times there wouldn't be anywhere for the recuperated energy to be stored. So it'd be wasted.

Agree, we don't want a full 48 Volt battery.

As to driving technique, I found that how fast you lift off the throttle, has a part in determining how the car then runs, whether to a coasting mode, (with or without engine on), or going into regeneration mode.

I sense it is picking up whether we ae intending some engine braking, (hence triggering the regeneration mode), or just want to coast down, or even hold speed.

Clearly if we make a lot of rapid starts (using boost from the battery) and fast stops (limits the regeneration time), battery will not have a lot of charge.

Anyone else finding how we ease off the throttle, having a direct relationship to regeneration?

[user1811]

Originally Posted by HighlandPete

Anyone else finding how we ease off the throttle, having a direct relationship to regeneration?

My limited experience (from a test drive) is that the car looks ahead using the camera. If there is traffic ahead, it slows down and recuperates energy. If the road ahead is clear, it coasts.

[HighlandPete]

Originally Posted by user1811

My limited experience (from a test drive) is that the car looks ahead using the camera. If there is traffic ahead, it slows down and recuperates energy. If the road ahead is clear, it coasts.

Yes, same here. Also knows whether you are out in the open and are simply coasting, or approaching a restricted area (30mph zone) and slows with regeneration. Even with the same 'light' throttle lift off to zero position.

[VINCER0]

Originally Posted by thakid22

The hybrid battery is used to power vehicle accessories as well. Headlights, radio, climate control, instrument panel, and various ecu's will all draw power from the lithium battery at rest (even when the engine is off).

Coasting does charge the hybrid battery, but to get maximum charging you need to apply moderate to firm braking pressure. Brisk stopping or slowing charges the battery pretty quickly. In normal traffic at a nice pace, the hybrid battery may never reach full charge. A brisk drive through a neighborhood with lots of stop signs in close proximity charges the battery fully, especially if you wait until the last moment to brake for the stop signs thus braking a little harder than normal.

That will top the battery off and it will stay in the upper range of full for a while. But if you just have to have it full all of the time you will have to repeat the procedure periodically. The system seems to love stop and go driving, or Moreno, the braking that accompanies it.

Alternatively, you can find an empty road at night and do a couple of hard braking/soft acceleration cycles at medium speeds and it will get you up to full relatively quickly. (Make sure no one is behind you to run into you though).

Thank you, that is so interesting I didn't realize the lithium battery was being used for vehicle accessories like lights and climate control (my ac is always on).

I think my OCD would be satisfied if the lithium battery was at least 4/5 bars because this is a weekend car and I only drive it occasionally (1-2x a month)...hence wanting to store it at around 80% charge to maintain optimal lithium battery health.

BTW I definitely remember other 2021 M340i owners mentioning eboost but I don't think I've had the chance to see an icon pop up yet indicating that it is on. What does it look like?

I'm going to use your and other member suggestions to try to drive at night in order to try to get to 4/5 bars.

[VINCER0]

Originally Posted by HighlandPete

Agree, we don't want a full 48 Volt battery.

As to driving technique, I found that how fast you lift off the throttle, has a part in determining how the car then runs, whether to a coasting mode, (with or without engine on), or going into regeneration mode.

I sense it is picking up whether we ae intending some engine braking, (hence triggering the regeneration mode), or just want to coast down, or even hold speed.

Clearly if we make a lot of rapid starts (using boost from the battery) and fast stops (limits the regeneration time), battery will not have a lot of charge.

Anyone else finding how we ease off the throttle, having a direct relationship to regeneration?

I drove in sports mode perpetually with the AC on and often make rapid starts...which now makes sense as to why my lithium battery is almost always at 2/5 bars.

On my next weekend drive, I'll try to make an observation on the throttle release response vs battery regeneration.

[VINCER0]

Originally Posted by gnolivos

Where is this battery menu / screen that there OP speaks of? I can't find it.

Car>Driving Information>Energy Flow

https://imgbb.com/X7y8348

[mat_m]

I have picked up my 2020 M340i three weeks ago. I have driven so many miles, and the battery on the screen above is always fully discharged. When engine breaking I see the animation showing charging occurs. But for three weeks the battery was never charged even a one bar. It always shows up as empty. Does this mean something is wrong with the system in my car? Any ideas how can I somehow diagnose it?

[ham340]

Originally Posted by mat_m

I have picked up my 2020 M340i three weeks ago. I have driven so many miles, and the battery on the screen above is always fully discharged. When engine breaking I see the animation showing charging occurs. But for three weeks the battery was never charged even a one bar. It always shows up as empty. Does this mean something is wrong with the system in my car? Any ideas how can I somehow diagnose it?

I believe that is correct as the 2020 does not have the mild hybrid system.