[TurtleBoy]

Originally Posted by MattAu

I am going back to find the post(s) where I thought I read there are three batteries.

I picked up the car last week and has been playing with it and a couple of days ago, I got a warning on my MyBMW app that says Starter Battery is severely drained! I now got myself a CTEK MXS 5.0 only to read that some of us have AGM but some has Li-ion ones. Unlike the BMW branded CTEK charger, the CTEK branded charger doesn't have a choice for Li-ion. Should I return it?

Someone probably misunderstood the dual storage system as well as the mild hybrid and thought there were three.

No, that is incorrect. No one has a Li-ion starter battery. All starter batteries are AGM. You will be fine using that charger.

[MattAu]

Originally Posted by TurtleBoy

Someone probably misunderstood the dual storage system as well as the mild hybrid and thought there were three.

No, that is incorrect. No one has a Li-ion starter battery. All starter batteries are AGM. You will be fine using that charger.

Thanks for clarifying. So there is a battery in the trunk, mine is 90AH AGM (A090) - is that the starter battery and the one that is being charged by the CTEK?

What about the battery under the hood? I see it could be either a 60Ah AGM or a 10Ah Li-ion. If I have the 10Ah Li-ion one, will the CTEK charge it as well?

[TurtleBoy]

Originally Posted by MattAu

Thanks for clarifying. So there is a battery in the trunk, mine is 90AH AGM (A090) - is that the starter battery and the one that is being charged by the CTEK?

What about the battery under the hood? I see it could be either a 60Ah AGM or a 10Ah Li-ion. If I have the 10Ah Li-ion one, will the CTEK charge it as well?

Let's take a step back, what year is your X5? I have been referring to the mild-hybrid as your original question was about the 48v battery. You wouldn't have the 10Ah battery if that was the case.

[Marty in NY]

Originally Posted by MattAu

I am going back to find the post(s) where I thought I read there are three batteries.

I picked up the car last week and has been playing with it and a couple of days ago, I got a warning on my MyBMW app that says Starter Battery is severely drained! I now got myself a CTEK MXS 5.0 only to read that some of us have AGM but some has Li-ion ones. Unlike the BMW branded CTEK charger, the CTEK branded charger doesn't have a choice for Li-ion. Should I return it?

Is this the one you bought?



This is the one I use on my X5, works great. Press the Mode button to select the battery type and like Turtleboy said, you will use AGM as that is the 12 battery under the cargo area in your car. If you received a severely drained message, there's no way to know if your battery will be able to be saved. It may indeed take a charge but it may not last, you won't know till trying it so go ahead, put the CTEK on it, select the right mode and connect it to the charging terminals in the engine bay, leave the hood open a bit and be prepared to wait up to three or four days of charging before the CTEK gets to the float stage. If it never does, you may need to replace the battery.

[MattAu]

Originally Posted by TurtleBoy

Let's take a step back, what year is your X5? I have been referring to the mild-hybrid as your original question was about the 48v battery. You wouldn't have the 10Ah battery if that was the case.

So sorry, mine is a 2021 xDrive40i. AFAIK it has the 48v Mild Hybrid. And mine has 2VR 2-axle air suspension so I think that means it doesn't have ASR and therefore it doesn't have the Li-ion battery under the hood. Am I right?

[MattAu]

Originally Posted by Marty in NY

Is this the one you bought?

Attachment 3363326

This is the one I use on my X5, works great. Press the Mode button to select the battery type and like Turtleboy said, you will use AGM as that is the 12 battery under the cargo area in your car. If you received a severely drained message, there's no way to know if your battery will be able to be saved. It may indeed take a charge but it may not last, you won't know till trying it so go ahead, put the CTEK on it, select the right mode and connect it to the charging terminals in the engine bay, leave the hood open a bit and be prepared to wait up to three or four days of charging before the CTEK gets to the float stage. If it never does, you may need to replace the battery.

It's actually at he dealer now. I was told its SOC was dropping from low 40's to mid 30's over the last 3 days and it was in the low 80's 4 days ago. They said it is being charged and seems to be fine. As a precaution, I bought the CTEK (same as the one in your picture) and figured I should probably use it like a lot of people have been.

[TurtleBoy]

Originally Posted by MattAu

So sorry, mine is a 2021 xDrive40i. AFAIK it has the 48v Mild Hybrid. And mine has 2VR 2-axle air suspension so I think that means it doesn't have ASR and therefore it doesn't have the Li-ion battery under the hood. Am I right?

Yes and no. You have the mild-hybrid so you have the 48v Li-ion under the hood.

The 10aH Li-Ion battery in the dual storage system were in vehicles that didn't have the active roll stabilization. For vehicles that did they had an AGM battery under the hood.

I have not seen the LCI technical docs but my understanding is the dual storage system goes away when the vehicle goes to the mild hybrid system so even those with ARS do not have another AGM

All that said, just charge your 12v on the AGM setting with the hood open and you should be fine assuming your battery is not shot.

[jad03060]

Depending on the model and options, you could have up to three batteries, but you should always use the charging terminals under the hood. IF you have a 48vdc battery, it will only be recharged manually if your battery charger can output more than 20A, which a battery tender generally cannot reach. When the 12vdc batteries are properly maintained, the system should be able to keep the 48vdc one charged. If you let them get too low, you may never get to recharge the 48vdc one adequately.

[TurtleBoy]

Originally Posted by jad03060

Depending on the model and options, you could have up to three batteries, but you should always use the charging terminals under the hood. IF you have a 48vdc battery, it will only be recharged manually if your battery charger can output more than 20A, which a battery tender generally cannot reach. When the 12vdc batteries are properly maintained, the system should be able to keep the 48vdc one charged. If you let them get too low, you may never get to recharge the 48vdc one adequately.

Can you give us a link to the docs on that? I have never seen anything showing three batteries.

[MattAu]

Originally Posted by TurtleBoy

Yes and no. You have the mild-hybrid so you have the 48v Li-ion under the hood.

The 10aH Li-Ion battery in the dual storage system were in vehicles that didn't have the active roll stabilization. For vehicles that did they had an AGM battery under the hood.

I have not seen the LCI technical docs but my understanding is the dual storage system goes away when the vehicle goes to the mild hybrid system so even those with ARS do not have another AGM

All that said, just charge your 12v on the AGM setting with the hood open and you should be fine assuming your battery is not shot.

Well, I guess I will know definitively once I pick up my car if there is a battery under the hood near the jump start posts (and if so, AGM or Li-ion). The salesman kept telling me I have a Li-ion battery in addition to the normal starter battery and said it could be the Li-ion one that's an issue. He said it's like a Dyson, it's full power until it dies.

From what you are saying, assuming they return the car back to me telling me all is good, then I should just start using the CTEK in AGM mode and need not worry anymore.

[TurtleBoy]

Originally Posted by MattAu

Well, I guess I will know definitively once I pick up my car if there is a battery under the hood near the jump start posts (and if so, AGM or Li-ion). The salesman kept telling me I have a Li-ion battery in addition to the normal starter battery and said it could be the Li-ion one that's an issue. He said it's like a Dyson, it's full power until it dies.

From what you are saying, assuming they return the car back to me telling me all is good, then I should just start using the CTEK in AGM mode and need not worry anymore.

I think you are missing something. How could it be an AGM? That is only used when a vehicle has ARS. Other than that it is always a Li-ion battery.

Yes, that is all you need to do.

I guess given the post above, the question is if the 48v hybrid system supplanted the dual storage system or is in addition to it.


Edit; I just looked up the 12v Li-ion battery (Part# 61215A4AF23) and it says it fits X5 40i up through 2023 (like wasn't updated for 24 yet) so given that it seems like there would be three batteries in all mild-hybrids.

[MattAu]

So in that case, how does my Li-ion auxiliary battery get charged/maintained using the CTEK? It only has AGM.

[TurtleBoy]

Originally Posted by MattAu

So in that case, how does my Li-ion auxiliary battery get charged/maintained using the CTEK? It only has AGM.

The batteries under the hood, no matter what they are, are not intended to be, nor need to be, charged separately by outside sources. Those are taken care of by the battery management system.

[Marty in NY]

Originally Posted by MattAu

So sorry, mine is a 2021 xDrive40i. AFAIK it has the 48v Mild Hybrid. And mine has 2VR 2-axle air suspension so I think that means it doesn't have ASR and therefore it doesn't have the Li-ion battery under the hood. Am I right?

You have what I have, a 2021 xDrive40i. It's a mild hybrid with the 12V AGM in the back and a 48V Li-on in the engine compartment and its missing the Auto Start/Stop button that used to be in the center console.

Now lets see if I have learned something here via this thread and those who have pitched in to help.. .. .. The 12V AGM (under the rear cargo area) is responsible, via the battery management system electronics, to keep the 48V properly charged. It does this via a DC-DC converter to increase the voltage from 12 to 48. When you connect your CTEK to the charge terminals in the engine bay, it will charge the 12V AGM. If the 12V AGM is not properly charged, goes bad, etc., it will no longer be able to properly charge the 48V battery.

Basically, if you have good batteries and drive the car on a regular basis you won't have anything to worry about. I do put the CTEK on mine once in a while but that's because it's a trip car and can sit idle for months at a time.

Have your dealer give you a good tour of the car and the battery system, pointing out where the batteries are and what they are responsible for, ask questions and be sure to pose the question about which battery they believed was losing charge, what they did to charge it and their thoughts on its ability to continue to hold a charge cause like I said, once a battery starts its decline to such low levels it can have irreparable damage and never hold a full charge again or not for very long.

[TurtleBoy]

Originally Posted by Marty in NY

You have what I have, a 2021 xDrive40i. It's a mild hybrid with the 12V AGM in the back and a 48V Li-on in the engine compartment and its missing the Auto Start/Stop button that used to be in the center console.

Now lets see if I have learned something here via this thread and those who have pitched in to help.. .. .. The 12V AGM (under the rear cargo area) is responsible, via the battery management system electronics, to keep the 48V properly charged. It does this via a DC-DC converter to increase the voltage from 12 to 48. When you connect your CTEK to the charge terminals in the engine bay, it will charge the 12V AGM. If the 12V AGM is not properly charged, goes bad, etc., it will no longer be able to properly charge the 48V battery..

From what was alluded to earlier and from what I saw when looking at the 12v 10aH Li-ion battery, you may have three batteries in total. The AGM in the back and the 12v Li-ion and the 48v Li-ion under the hood. When you have time, see if you can find them.

I think the way the 48v battery is charged is using the alternator. It may also be charged with the 12v AGM but have not seen anything on that.

[Marty in NY]

Originally Posted by TurtleBoy

From what was alluded to earlier and from what I saw when looking at the 12v 10aH Li-ion battery, you may have three batteries in total. The AGM in the back and the 12v Li-ion and the 48v Li-ion under the hood. When you have time, see if you can find them.

I think the way the 48v battery is charged is using the alternator. It may also be charged with the 12v AGM but have not seen anything on that.

I've never seen a third battery in my car but since today happens to be a really nice NY day with sunshine and 50F, I'm on my way out to inspect. Our weather is about to start heading downhill fast with this low pressure storm hitting in a few hours. Be back atcha.. .. grab some popcorn in the meantime.

[TurtleBoy]

Originally Posted by Marty in NY

I've never seen a third battery in my car but since today happens to be a really nice NY day with sunshine and 50F, I'm on my way out to inspect. Our weather is about to start heading downhill fast with this low pressure storm hitting in a few hours. Be back atcha.. .. grab some popcorn in the meantime.

Sounds good. I have never thought about there being a third one as I always assumed the mild hybrid replaced the dual storage system. When I looked at the 12v Li-ion battery it shows it is also used in the mild hybrid.

My M430i is a mild-hybrid and never noticed a third one but never looked for it.

[Marty in NY]

Originally Posted by TurtleBoy

Sounds good. I have never thought about there being a third one as I always assumed the mild hybrid replaced the dual storage system. When I looked at the 12v Li-ion battery it shows it is also used in the mild hybrid.

My M430i is a mild-hybrid and never noticed a third one but never looked for it.

Ok, I just looked.. ..



I only found two, the 12v AGM in the back and the 48v Li-ion in the engine bay. I also looked for that missing ASS button, but still to this day cannot find it ... dang!

[TurtleBoy]

Originally Posted by Marty in NY

Ok, I just looked.. ..



I only found two, the 12v AGM in the back and the 48v Li-ion in the engine bay. I also looked for that missing ASS button, but still to this day cannot find it ... dang!

Thank you for looking. That is what I would have expected until having three batteries was brought up.

The interesting thing is that on multiple sites it says the 12v Li-ion battery for the dual storage is for the 2021 40i.

[Marty in NY]

Originally Posted by TurtleBoy

Thank you for looking. That is what I would have expected until having three batteries was brought up.

The interesting thing is that on multiple sites it says the 12v Li-ion battery for the dual storage is for the 2021 40i.

It is a bit confusing since both the 12v Li-ion and the 48v Li-ion are both 10Ah and some documentation only list the amp hours and not the voltage from what I've seen. Whether you get a 60Ah AGM or a 10Ah Li-ion in the engine bay is determined on whether the car came with Active Roll Stabilization or not. The ARS gets the AGM 60Ah battery in the engine bay. I've not found where a 12v Li-ion battery is used yet. Maybe it was used before they removed ASS on the 2021 model year which is when they went to a 48v Li-ion - yes, no? or since there is a Dual Storage System version 1 and 2, maybe it was in the 1 and the 48 went in the 2.

Here's some related stuff.. ..

[TurtleBoy]

Originally Posted by Marty in NY

It is a bit confusing since both the 12v Li-ion and the 48v Li-ion are both 10Ah and some documentation only list the amp hours and not the voltage from what I've seen. Whether you get a 60Ah AGM or a 10Ah Li-ion in the engine bay is determined on whether the car came with Active Roll Stabilization or not. The ARS gets the AGM 60Ah battery in the engine bay. I've not found where a 12v Li-ion battery is used yet. Maybe it was used before they removed ASS on the 2021 model year which is when they went to a 48v Li-ion - yes, no? or since there is a Dual Storage System version 1 and 2, maybe it was in the 1 and the 48 went in the 2.

Here's some related stuff.. ..

As far as what we are seeing, none of that applies to the mild-hybrids. That is the dual storage system that evidently was replaced in MH's. The LI-ion battery that is referring to is the 12v one.

Version 1 of the dual storage is when the AGM battery is under the hood.

[Marty in NY]

Originally Posted by TurtleBoy

As far as what we are seeing, none of that applies to the mild-hybrids. That is the dual storage system that evidently was replaced in MH's. The LI-ion battery that is referring to is the 12v one.

Version 1 of the dual storage is when the AGM battery is under the hood.

Then over time there were multiple batteries used depending on the year and options but at no time were there three batteries in the car at the same time. Is this what its boiling down to?