all about M8 battery

Volcanic · 08-30-2022, 03:03 PM

Does anyone have the link to an actual M8 replacement battery? I'm curious as to the cost of these.

Tenac · 08-30-2022, 03:12 PM

61218092860 about 1200

RJC-1 · 08-30-2022, 03:20 PM

Quote:

Originally Posted by Tenac

I only looked up the M8 which only has one batter and it is Lion. Not sure about the M850i.....

According to the BMW manual jumping is only allowed from those posts upfront because they are protected on the positive side before the battery. So if the M850i only has one battery like the M8 you can trickle it from there as well.

The M850 has two batteries, AGM in trunk and Lith in engine compt...so I can't imagine the M8 only having one

The Lith in the link above is for the "starter battery" which seems to infer it's only for that purpose and there may be an AGM for other electronics.

Tenac · 08-30-2022, 03:24 PM

Quote:

Originally Posted by RJC-1

The M850 has two batteries, AGM in trunk and Lith in engine compt...so I can't imagine the M8 only having one

This all it shows on the electrical diagram and break down. Has two battery buy options but they are the same.

https://bimmercat.com/bmw/en/search/...M8/USA/61_5973

RJC-1 · 08-30-2022, 05:28 PM

Quote:

Originally Posted by Tenac

This all it shows on the electrical diagram and break down. Has two battery buy options but they are the same.

https://bimmercat.com/bmw/en/search/...M8/USA/61_5973

I know it was asked previously in another thread by bloozemanAZ why the M850 has both AGM and LIO, and if the M8's do as well, and if not why so, but it was never answered. Maybe someone here knows for sure.

https://f92.bimmerpost.com/forums/sh...62&postcount=4

Tenac · 08-30-2022, 05:58 PM

Quote:

Originally Posted by RJC-1

I know it was asked previously in another thread by bloozemanAZ why the M850 has both AGM and LIO, and if the M8's do as well, and if not why so, but it was never answered. Maybe someone here knows for sure.

https://f92.bimmerpost.com/forums/sh...62&postcount=4

Called my SA he said no the only battery listed for the M8 is the Lion or lithium. I'm in travel so I cannot actually pop the hood to look but I know 100% there is only one in the trunk area.

RJC-1 · 08-31-2022, 02:00 PM

Quote:

Originally Posted by Tenac

Called my SA he said no the only battery listed for the M8 is the Lion or lithium. I'm in travel so I cannot actually pop the hood to look but I know 100% there is only one in the trunk area.

In the M850 the lith is in the engine compt, and the AGM is in the trunk. Still need to know what the charging posts go to in the engine compartment of the M850's...the AGM or lith?

Tenac · 08-31-2022, 02:24 PM

Quote:

Originally Posted by RJC-1

In the M850 the lith is in the engine compt, and the AGM is in the trunk. Still need to know what the charging posts go to in the engine compartment of the M850's...the AGM or lith?

I would call and talk with your local service team as well, but according to what I've read for the dual battery. When you are connect on the post under the hood. The charger is connected directly to the battery management electronics. That unit will decide which battery gets power and only the power the battery is allowed to keep from overvolts or overcharge. So sounds like use which ever unit you really want just make sure NOT to connect it directly to either battery or the other unit will miss out and potential for the battery management system to fail.

Oh and with a bit more deep dive it looks like some M850i's have three batteries in total, two AGM and one Lith.

Tethys · 08-31-2022, 02:37 PM

I could imagine them using only one battery on the M8 to save weight, I know I've never seen a battery under the hood of my M8 while working on it but never really looked for one. I can't imagine where it would be.

RJC-1 · 08-31-2022, 04:10 PM

Quote:

Originally Posted by Tenac

I would call and talk with your local service team as well, but according to what I've read for the dual battery. When you are connect on the post under the hood. The charger is connected directly to the battery management electronics. That unit will decide which battery gets power and only the power the battery is allowed to keep from overvolts or overcharge. So sounds like use which ever unit you really want just make sure NOT to connect it directly to either battery or the other unit will miss out and potential for the battery management system to fail.

Oh and with a bit more deep dive it looks like some M850i's have three batteries in total, two AGM and one Lith.

Thanks for the info., yes I always connect to the charging posts only. I will ask my SA for more info next time I go in for service, but my guess is he'd need to contact BMW USA. I do have the top-of-the-line BMW charger which I've used in the past but was never sure exactly which battery it was charging. https://www.shopbmwusa.com/product/1...ATTERY-CHARGER

RJC-1 · 08-31-2022, 04:13 PM

Quote:

Originally Posted by Tethys

I could imagine them using only one battery on the M8 to save weight, I know I've never seen a battery under the hood of my M8 while working on it but never really looked for one. I can't imagine where it would be.

In the M850 the lith battery is located under a similar panel located here in the M8, but from what I can see in the pic it looks relatively empty in there:

Tethys · 08-31-2022, 04:41 PM

Quote:

Originally Posted by RJC-1

In the M850 the lith battery is located under a similar panel located here in the M8, but from what I can see in the pic it looks relatively empty in there:

Yeah I've opened that looking around and didn't see anything in there. Give me about 10 minutes and I'll go look again and be sure.

Tethys · 08-31-2022, 05:04 PM

Quote:

Originally Posted by RJC-1

In the M850 the lith battery is located under a similar panel located here in the M8, but from what I can see in the pic it looks relatively empty in there:

Looked and there isn't anything there.

RJC-1 · 08-31-2022, 05:28 PM

Quote:

Originally Posted by Tethys

Looked and there isn't anything there.

Just as I suspected, the question remains why does the M850 get additional batteries and the M8 not? Weight could certainly be an answer but then how did they make up all that missing power...thinking a much more powerful Lith for the M8?

Tethys · 08-31-2022, 05:42 PM

Quote:

Originally Posted by RJC-1

Just as I suspected, the question remains why does the M850 get additional batteries and the M8 not? Weight could certainly be an answer but then how did they make up all that missing power...thinking a much more powerful Lith for the M8?

Good question but lithium batteries are way more powerful than AGM so why do an AGM at all in the 850?

Tenac · 08-31-2022, 09:03 PM

Quote:

Originally Posted by Tethys

Good question but lithium batteries are way more powerful than AGM so why do an AGM at all in the 850?

Not exactly true, for our M8 you can find a replacement AGM that outputs the same.

As far as why two batteries on the M850i compared to the M8... Heck dunno we will ever know that. It could be weight, or it could be the tech in the M850i was more of a hybrid get it working before they went full Lithium. Dunno

RJC-1 · 08-31-2022, 09:11 PM

Quote:

Originally Posted by Tenac

Quote:

Originally Posted by Tethys

Good question but lithium batteries are way more powerful than AGM so why do an AGM at all in the 850?

Not exactly true, for our M8 you can find a replacement AGM that outputs the same.

As far as why two batteries on the M850i compared to the M8... Heck dunno we will ever know that. It could be weight, or it could be the tech in the M850i was more of a hybrid get it working before they went full Lithium. Dunno

Must be b/c of the M850's flux capacitor

snowbimmer · 08-31-2022, 10:20 PM

Quote:

Originally Posted by RJC-1

Quote:

Originally Posted by Tenac

Quote:

Originally Posted by Tethys

Good question but lithium batteries are way more powerful than AGM so why do an AGM at all in the 850?

Not exactly true, for our M8 you can find a replacement AGM that outputs the same.

As far as why two batteries on the M850i compared to the M8... Heck dunno we will ever know that. It could be weight, or it could be the tech in the M850i was more of a hybrid get it working before they went full Lithium. Dunno

Must be b/c of the M850's flux capacitor

Or, the extra one is used to charge the dylithium crystals.

Tethys · 09-01-2022, 07:46 AM

Quote:

Originally Posted by Tenac

Not exactly true, for our M8 you can find a replacement AGM that outputs the same.

As far as why two batteries on the M850i compared to the M8... Heck dunno we will ever know that. It could be weight, or it could be the tech in the M850i was more of a hybrid get it working before they went full Lithium. Dunno

Pound for pound and size lithiums output way more than AGM. There's a reason they use lithiums to power electric cars and not AGMs.

Tenac · 09-01-2022, 09:38 AM

Quote:

Originally Posted by Tethys

Pound for pound and size lithiums output way more than AGM. There's a reason they use lithiums to power electric cars and not AGMs.

Yeah that is why I said weight savings. But for power it will be equal to what is needed only. If you look in the trunk you can see the larger room for the AGM is there.

Tethys · 09-01-2022, 10:01 AM

Quote:

Originally Posted by Tenac

Yeah that is why I said weight savings. But for power it will be equal to what is needed only. If you look in the trunk you can see the larger room for the AGM is there.

I'll have to look, I haven't taken anything apart in this car yet except when I put intakes on it.

Suds2023 · 10-23-2022, 08:29 AM

I too have a 2023 M8 and will store it in the winter. You are right, this information is not found in the Owner’s Manual.

I just purchased an OEM Battery “Charger” (that’s their term for the maintainer). It has a Lithium Ion setting.

According to the instructions with the Charger:

When you first use it, detach the charging clips and plug the main plug into the wall socket and set it Lithium Ion. Then, unplug and attach the charging clips to the maintainer. Now, attach the red clip (under the hood as previously suggested) and then the black to ground post also under the hood. Then plug the main plug into the wall socket. It states that it will automatically go Lithium Ion mode.

It appears the process is pretty straightforward. I will put my car away by around mid November.

08-30-2022, 03:03 PM	#23
Volcanic Private 168 Rep 64 Posts Drives: 2023 M8C Vert, 2007 M6 Vert Join Date: Aug 2022 Location: Auburn, WA iTrader: (0)	Does anyone have the link to an actual M8 replacement battery? I'm curious as to the cost of these.
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08-30-2022, 03:12 PM	#24
Tenac Brigadier General 4540 Rep 3,507 Posts Drives: All Join Date: Mar 2019 Location: AZ iTrader: (0)	61218092860 about 1200 __________________ 2022 M8 Comp Convertible 2023 718 Cayman GTS 4.0 2019 718 Cayman Base 2015 M235 Manual On the list for the M2 CS Last edited by Tenac; 08-30-2022 at 03:24 PM..
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08-31-2022, 02:37 PM	#31
Tethys Lieutenant 406 Rep 421 Posts Drives: BMW M4 Comp, 330i, Camaro SS Join Date: Nov 2021 Location: Bartlett, TN iTrader: (0) Garage List 2022 BMW M4 Competiton [0.00]	I could imagine them using only one battery on the M8 to save weight, I know I've never seen a battery under the hood of my M8 while working on it but never really looked for one. I can't imagine where it would be.
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10-23-2022, 08:29 AM	#44
Suds2023 Registered 0 Rep 1 Posts Drives: 2023 BMW M8 Competition Conver Join Date: Oct 2022 Location: Toronto, Ontario, Canada iTrader: (0)	Same battery question I too have a 2023 M8 and will store it in the winter. You are right, this information is not found in the Owner’s Manual. I just purchased an OEM Battery “Charger” (that’s their term for the maintainer). It has a Lithium Ion setting. According to the instructions with the Charger: When you first use it, detach the charging clips and plug the main plug into the wall socket and set it Lithium Ion. Then, unplug and attach the charging clips to the maintainer. Now, attach the red clip (under the hood as previously suggested) and then the black to ground post also under the hood. Then plug the main plug into the wall socket. It states that it will automatically go Lithium Ion mode. It appears the process is pretty straightforward. I will put my car away by around mid November.
	Appreciate 0 Quote