[mysore]

I will be out for about two months and my m60 will sit in the garage for the whole duration. I will enable deep sleep mode in the car, but I am afraid the battery will drain based on postings on this forum. Is there a recommended charger that I should use to keep the car battery healthy? I also worry about safety, are these chargers safe to use in a closed garage unattended for 2 months?

[streborx]

Originally Posted by mysore

I will be out for about two months and my m60 will sit in the garage for the whole duration. I will enable deep sleep mode in the car, but I am afraid the battery will drain based on postings on this forum. Is there a recommended charger that I should use to keep the car battery healthy? I also worry about safety, are these chargers safe to use in a closed garage unattended for 2 months?

BMW's branded maintenance charger (CTEK) is used by many forum members. I used a Noco charger on my X7 while I had it in winter storage last year (and will again beginning next month), and it worked fine. These are smart chargers that don't overcharge and provide modest charging current.

[mysore]

Originally Posted by streborx

BMW's branded maintenance charger (CTEK) is used by many forum members. I used a Noco charger on my X7 while I had it in winter storage last year (and will again beginning next month), and it worked fine. These are smart chargers that don't overcharge and provide modest charging current.

I suppose I should get a 12V charger any specific amps that I should pickup?

[RidgeHauler]

I've been using CTEK for my cars and NOCO on my boat with no issues.

[crazyinp]

Originally Posted by mysore

I suppose I should get a 12V charger any specific amps that I should pickup?

when you connect it inside the engine bay, IBS controls how much AMPs are going into the system. I usually use 10A NOCO for when I don't drive the car and I have power supply for charging that can provide up to 80a. I have notice the car would adjust how much to draw based on the needs

[jad03060]

You want a battery maintenance device that understands AGM batteries. Generally, there's no need for more than about 10A and usually less is adequate.

Many of them will recover if there's a power outage, but not all, so if you do get one, it may reset itself to off, which depending on when that happened, may not buy you much. I've had a Bosch unit for years, but this one does not turn itself back on if there's a power outage. Probably not what you want if nobody can check on it periodically. My last ICE vehicle didn't get driven much. The original battery was replaced after a year under warranty. I bought the Bosch unit, and the next one lasted 7-years...says something to me at least.

The BMW battery logic works IF you drive it regularly, but can have some issues if you don't.

[streborx]

Originally Posted by mysore

I suppose I should get a 12V charger any specific amps that I should pickup?

The Noco charger I bought is the "2 x 2" -- two isolated outputs rated at 2 amps each. I bought this because my X7 has two 12 volt AGM batteries -- one in the boot (the main starter battery) and another in the engine compartment (for the suspension and/or dynamic handling systems, I think. It's not a 48 volt lithium for a mild hybrid system.). I had a tough time getting an answer out of BMW regarding the long term (6 months) charging requirements, and thought I might need to put both batteries on maintenance charging. BMW finally told me only the main battery needs charging, and the secondary battery will automatically charge if/when needed via the charging controller that maintains both batteries. I connected only the main battery to the charger, and monitored the voltage on both batteries all winter. The secondary battery stayed at 12.6 volts the entire storage period -- never dropped, but never increased either. So it was apparently completely relieved of any load with the car parked and off. The main battery behaved normally with shallow discharge and recharge cycles. Will be monitoring again this winter.

[biterror]

Originally Posted by crazyinp

when you connect it inside the engine bay, IBS controls how much AMPs are going into the system.

IBS controls the car's alternator, but it can't control an external charger. IBS can only monitor the charge status of the battery in this case (provided that the charger is connected under the hood, not directly to the battery).

[jad03060]

The only hiccup is if you have the mild hybrid with a 48vdc lithium battery. A SIB on that you can probably find with a search, said two important things:
- the 48vdc battery won't be charged unless the hood is open
- the 48vdc battery won't be charged unless the input is >20A

It also mentioned disconnecting the 48vdc battery when the vehicle is sitting in a showroom, as it's not needed, and >20A is too much for the 12vdc battery(s) to handle long-term once they're fully charged. All of the 'normal' stuff you'd interact with on a vehicle sitting in the showroom runs off of the 12vdc.

Using the terminals under the hood SHOULD maintain all of the 12vdc batteries in the vehicle.

On a mild hybrid, I don't think there's any load on the 48vdc battery while just sitting there, but I do not know for sure. That type of battery does have a very low self-discharge rate.

[biterror]

Originally Posted by jad03060

It also mentioned disconnecting the 48vdc battery when the vehicle is sitting in a showroom, as it's not needed, and >20A is too much for the 12vdc battery(s) to handle long-term once they're fully charged.

When the battery is fully charged, there's no current flowing whether you're using a 2 A or 200 A (smart) charger. So a 20 A charger is not a problem.

[jad03060]

Having an excess of voltage on the batteries can cause them to overheat once they are fully charged. Smart chargers, versus dumb ones recognize that fact...dumb ones do not.

If you choose a smart one, it should work. Those monitor the actual battery voltage, and then either pulse or shut down until their voltage level decreases to maintain them...a dumb one just keeps applying charging voltage.

[crazyinp]

Originally Posted by biterror

IBS controls the car's alternator, but it can't control an external charger. IBS can only monitor the charge status of the battery in this case (provided that the charger is connected under the hood, not directly to the battery).

I am sure you look at the diagram but the power from the alternator, along with the power from the engine compartment external terminal and the one going to the started are all connected in the power box under the front hood. IBS sends signal to the DME that controls how much of that is going to the battery. So technically you can use any dump charger as long as you use the power terminal under the hood, and only what is needed will be going to the battery. Also, I can confirm that from my coding charger that hits north of 80A when need it.

[RidgeHauler]

I have only charged the rear 12 volt battery via pigtails attached to that battery to my CTEK. It will charge that battery without issue with all doors and hood closed.

I haven't attempted to charge via the engine compartment remote connections. I don't know enough about the entire system (48 Volt) and wanted to keep it direct to reduce the likelihood of undesirable issues.

[biterror]

Originally Posted by crazyinp

I am sure you look at the diagram but the power from the alternator, along with the power from the engine compartment external terminal and the one going to the started are all connected in the power box under the front hood. IBS sends signal to the DME that controls how much of that is going to the battery. So technically you can use any dump charger as long as you use the power terminal under the hood, and only what is needed will be going to the battery. Also, I can confirm that from my coding charger that hits north of 80A when need it.

At least on my F11, IBS controls the alternator and can adjust the alternator output voltage, which controls the battery charging current. I believe it works the same way in G05. There's no point for the alternator to generate "too much electricity" (where would it go, anyway?). An external charger must control the voltage (and so, the current) by itself..

[LDT]

CTEK

[mysore]

Overwhelmed by ton of information, thank you all. Does anyone have a picture showing how the charger is connected under the hood? I suppose a smart charger should eliminate risk of fire or other hazards, just worried because we would have no one at home for 2 months

[crazyinp]

Originally Posted by biterror

At least on my F11, IBS controls the alternator and can adjust the alternator output voltage, which controls the battery charging current. I believe it works the same way in G05. There's no point for the alternator to generate "too much electricity" (where would it go, anyway?). An external charger must control the voltage (and so, the current) by itself..

Can't post picture but the diagram is available in the sticky. You can see how single and dual storage system is wired in G05.

[jad03060]

Does anybody ever read the user's manual? The connection is shown there.

[mysore]

Originally Posted by jad03060

Does anybody ever read the user's manual? The connection is shown there.

I am probably not looking in the right place. I have checked users guide app on my mobile and I can’t find a schematic. Can you point me to it?

[streborx]

Does anyone know why this "hood up" state is required for charging the 48 volt battery? Does it serve any purpose other than reducing the amount of time an owner equipped with a fire extinguisher has to react?

[TurtleBoy]

Originally Posted by streborx

Does anyone know why this "hood up" state is required for charging the 48 volt battery? Does it serve any purpose other than reducing the amount of time an owner equipped with a fire extinguisher has to react?

The 48v battery does not charge with the hood closed so depending on length of time it can become discharged, damaged and need ot be replaced.

https://static.nhtsa.gov/odi/tsbs/20...88948-9999.pdf

[streborx]

Originally Posted by TurtleBoy

The 48v battery does not charge with the hood closed so depending on length of time it can become discharged, damaged and need ot be replaced.

https://static.nhtsa.gov/odi/tsbs/20...88948-9999.pdf

Yes, this is now known, but why does does this battery tend to discharge when the vehicle is parked in a showroom? Even the dealers weren't advised of this prior to the SIB. If the 48 volt battery is used only for the mild hybrid ISG, and its self-discharge is negligible (as postulated in post #9 above), why does the hood need to be up when charging the 12 volt battery so that the 48 volt battery can also charge?