Lithium Battery

alvitdk · 06-26-2023, 05:17 PM

Figured starting a new thread after searches are rather inconclusive.

On my M40i I do have a screen that shows a power flow in the display when braking...charging a battery. As the regular starter battery is likely also charged when under power....there must be a second battery in the car, I assume. However, reading through all the posts, the M40I is not supposed to have a second battery (can't check due to ppf installation car not being home). If it indeed does not have one, what is it charging when braking?

stlcdr · 06-26-2023, 05:36 PM

So, this has been mentioned before, buried in threads. The M40i does not have a second battery.

On the right side there’s a space under some trim in the engine bay, enough to hold a battery. I believe other models (euro models?) have a battery, there. There was some discussion regarding the purpose, and effectiveness.

alvitdk · 06-26-2023, 05:43 PM

Quote:

Originally Posted by stlcdr

So, this has been mentioned before, buried in threads. The M40i does not have a second battery.

On the right side there’s a space under some trim in the engine bay, enough to hold a battery. I believe other models (euro models?) have a battery, there. There was some discussion regarding the purpose, and effectiveness.

That's what I thought, but that leaves me with the screen showing a "Power Flow" from the transmission to a "Battery", but only when braking, not when driving or coasting...

RigaTony1982 · 06-26-2023, 05:52 PM

My previous car (M340i) had the 48v mild hybrid setup and there was a second battery under the hood on the passenger side. It’s not there on my Z4. I believe the Z4 is the only car left with the B58 that doesn’t have the hybrid setup.

ebirotedu · 06-26-2023, 06:10 PM

Someone posted a link to some BMW marketing material that suggested that the alternator has some sort of clutch that reduces or disengages completely when the M40i is under acceleration, and conversely engages when decelerating - hence the charging icon.

As stlcdr says, this topic came up some months ago in another thread, but it's difficult to find via forum search.

Quote:

Originally Posted by alvitdk

That's what I thought, but that leaves me with the screen showing a "Power Flow" from the transmission to a "Battery", but only when braking, not when driving or coasting...

alvitdk · 06-26-2023, 06:19 PM

Quote:

Originally Posted by ebirotedu

Someone posted a link to some BMW marketing material that suggested that the alternator has some sort of clutch that reduces or disengages completely when the M40i is under acceleration, and conversely engages when decelerating - hence the charging icon.

As stlcdr says, this topic came up some months ago in another thread, but it's difficult to find via forum search.

That makes sense but there are two different modes in that screen. In eco+ it shows when coasting “transmission disengaged” but in any other mode “charging” when braking. Anyway, not that important and just curious.

BEAR-AvHistory · 06-26-2023, 06:33 PM

Car has regenerative braking. Brake applications will send a charge to the single battery.

StanDiego · 06-26-2023, 11:21 PM

Quote:

Originally Posted by alvitdk

Figured starting a new thread after searches are rather inconclusive.

On my M40i I do have a screen that shows a power flow in the display when braking...charging a battery. As the regular starter battery is likely also charged when under power....there must be a second battery in the car, I assume. However, reading through all the posts, the M40I is not supposed to have a second battery (can't check due to ppf installation car not being home). If it indeed does not have one, what is it charging when braking?

It's charging the elusive flux capacitor.

Sorry, no the M40i has no second battery, only the s30i.

Amadeo · 06-27-2023, 04:01 AM

Quote:

Originally Posted by StanDiego

It's charging the elusive flux capacitor.

Sorry, no the M40i has no second battery, only the s30i.

30i in Europe has no second battery. Maybe just in the US?.

StanDiego · 06-27-2023, 12:24 PM

Quote:

Originally Posted by Amadeo

30i in Europe has no second battery. Maybe just in the US?.

I'm unsure if it's just the US (Canada?) but yes, it was confirmed European 30i models don't include the second battery.

06-26-2023, 05:17 PM	#1
alvitdk Lieutenant 246 Rep 480 Posts Drives: 2023 BMW Z4 M40i Join Date: Nov 2011 Location: Texas iTrader: (2) Garage List 2023 BMW Z4 M40i [7.50] 2022 Nissan Frontie ... [0.00] 2023 Tesla Model 3 RWD [0.00]	Lithium Battery Figured starting a new thread after searches are rather inconclusive. On my M40i I do have a screen that shows a power flow in the display when braking...charging a battery. As the regular starter battery is likely also charged when under power....there must be a second battery in the car, I assume. However, reading through all the posts, the M40I is not supposed to have a second battery (can't check due to ppf installation car not being home). If it indeed does not have one, what is it charging when braking? __________________ --------------------------------------------------------------- 23' BMW Z4 M40i: Also Drive: 23' Tesla Model 3 Also Drive: 22' Nissan Frontier Pro 4X Waiting for 23' BMW Z4 M40i:
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06-26-2023, 05:36 PM	#2
stlcdr Captain 1015 Rep 681 Posts Drives: 2022 Z4 M40i Join Date: Feb 2022 Location: Kentucky iTrader: (0)	So, this has been mentioned before, buried in threads. The M40i does not have a second battery. On the right side there’s a space under some trim in the engine bay, enough to hold a battery. I believe other models (euro models?) have a battery, there. There was some discussion regarding the purpose, and effectiveness. __________________ 2022 BMW Z4 M40i \| 2021 HD Road Glide Limited \| 2019 Ford Expedition XLT MAX \| Subaru Outback 2019 \| Subaru Outback 2024
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06-26-2023, 05:52 PM	#4
RigaTony1982 Colonel 2596 Rep 2,062 Posts Drives: 2023 BMW Z4 M40i Join Date: Mar 2021 Location: Chicago iTrader: (0) Garage List 2023 BMW Z4 M40i [7.75]	My previous car (M340i) had the 48v mild hybrid setup and there was a second battery under the hood on the passenger side. It’s not there on my Z4. I believe the Z4 is the only car left with the B58 that doesn’t have the hybrid setup.
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06-26-2023, 06:33 PM	#7
BEAR-AvHistory 2020 Z4 M40i - 2022 M4C Convt 3129 Rep 5,264 Posts Drives: 2020 Z4 M40i - 2022 M4C Convrt Join Date: Jun 2011 Location: Raleigh, NC - OIB, NC iTrader: (0) Garage List 1965 COBRA (FFR rep ... [8.57] 2023 Jeep Wrangler ... [9.50] 2009 Yamaha V-Star [0.00] Cars 2-BMW, 2-FORD, ... [0.00] 2023 Ford Expeditio ... [0.00] 2020 Z4 M40i [10.00] 2022 BMW M4C [7.25] 1998 FORD Ranger 4X4 [0.00]	Car has regenerative braking. Brake applications will send a charge to the single battery. __________________ Kevin Dravit Gray, Black Leather, Moonlight Roof, Red Calipers 2022 M4C - 2020 Z4 M40i - 2023 FORD Expedition XLT Max 4X4 400BHP - 2009 V-Star - 1998 Ranger 4X4 5MT - 1965 Cobra (R) 5MT - 2023 Jeep Wrangler Sport S 6MT
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