[lmgee]

I have a 2021 330i xDrive. I noticed there appears to be a second battery in the engine compartment on the right side near the windshield. Inasmuch as the car is not an 330e nor an M model with mild hybrid, what is the second battery for?

[Jtw318]

Originally Posted by lmgee

I have a 2021 330i xDrive. I noticed there appears to be a second battery in the engine compartment on the right side near the windshield. Inasmuch as the car is not an 330e nor an M model with mild hybrid, what is the second battery for?

Aren't the 2021s a mild hybrid?

I could be wrong obviously, but sounds like it was fitted with the 330e battery? lol. I think in the none E's that spot is just empty.

Have a picture?

[G22b58]

Can you read the label? I suspect it is a 12V Li-Ion battery. My understanding is that these are better at cycling charge in order to save fuel and not cycling the starter lead battery as much.

[lmgee]

Thanks G22b58, it seems that you were right on target!

[G30M]

my car is a mild hybrid and does not have this battery. the space is empty, very tempted to put a bag of fruits/potatoes in there when i visit the grocer

[G22b58]

I thought "Imgee" found the secondary 12V Li-Ion battery in the same location instead of the MHEV-battery. My MHEV M440i has a 44V Li-Ion (440Wh) in the indicated location (in section Mild Hybrid page 371 in my owner's manual)

[G30M]

thanks, so some cars have both a lead acid battery and a 12V li ion battery (AND a 44V Li ion battery!!)

[G22b58]

MHEV models have the 44V Li-Ion battery on the (cars) right side in the engine compartment. It is my understanding that "Imgee" found that the non-MHEV 330i instead has a 12V Li-Ion at the same place instead of a MHEV battery.
If you don't have a 44V Li-Ion battery at this place in your M340i, isn't your car the earlier model (without 48V system)?
Do you have a Stop/Start-disable button next to the engine Start-Stop button?

[G30M]

my car has the battery charging and discharging on the energy flow section and the dealer says it has mild hybrid, but empty space for my grocery

[k4sh_90]

Mine is a 20, and has the second battery. It's a dual supply system, I think primarily to reduce battery wear with the auto start/stop and running vehicle electronics.

[Mr.G20 M340]

Has anyone found out how much it is to replace this battery? I have a 2020 and it is giving me trouble

[aia112]

2021 330i xdrive us spec. I am not sure if I have to register the auxiliary battery too. I don’t think I do because I don’t see IBS. Check out the image does it have IBS? Do I need to register this battery too?

Thanks in advance

[larrylam646]

Originally Posted by aia112

2021 330i xdrive us spec. I am not sure if I have to register the auxiliary battery too. I don’t think I do because I don’t see IBS. Check out the image does it have IBS? Do I need to register this battery too?

Thanks in advance

The dual storage (2nd) 12V battery has is own electronics that is built into the battery casing (unlike the IBS connected to the negative terminal of the 12V AGM System battery) - Reference ISTA+

Yes, the dual storage 12V battery has to be registered when replaced (ISTA+ Path: 03 body > voltage supply > dual store system registration).

Larry

[aia112]

Originally Posted by larrylam646

The dual storage (2nd) 12V battery has is own electronics that is built into the battery casing (unlike the IBS connected to the negative terminal of the 12V AGM System battery) - Reference ISTA+

Yes, the dual storage 12V battery has to be registered when replaced (ISTA+ Path: 03 body > voltage supply > dual store system registration).

Larry

I can register the main battery with bimmerlink but not this one unfortunately. I wish I have ISTA+ anyone can help? If I do replace it do I have to get genuine bmw part since it has built in electronics inside the battery or other lithium ion battery( same size ) from another brand will do?

[larrylam646]

Originally Posted by aia112

I can register the main battery with bimmerlink but not this one unfortunately. I wish I have ISTA+ anyone can help?

Try reaching out to shawnsheridan ... see thread - https://g20.bimmerpost.com/forums/sh....php?t=2013967

Originally Posted by aia112

If I do replace it do I have to get genuine bmw part since it has built in electronics inside the battery or other lithium ion battery( same size ) from another brand will do?

i do not know.

[pn02138]

Originally Posted by Mr.G20 M340

Has anyone found out how much it is to replace this battery? I have a 2020 and it is giving me trouble

My car was running fine, and on engine light check, mechanic showed a dead Li-ion battery code. $750 to replace.

[Mr.G20 M340]

Originally Posted by pn02138

My car was running fine, and on engine light check, mechanic showed a dead Li-ion battery code. $750 to replace.

Damn for a tiny battery like that. I took a risk and decided to replace my starter and thankfully that fixed my issue. As for li-ion battery I called a shop and he had someone who was able to repair lithium ion batteries if they had a bad cell. Don’t think I’d take that risk though.