[d3mon]

Originally Posted by mikem

Quite surprised as my W212 has a battery voltage of 11.6 volts parked in the mornings, even after a week of no use; and no issues for me. Charging volts are 13.6-14.1. It’s been stagnant at this voltage (11.6v) for over a year.

Is it time to get a trickle charger or get the battery replaced?

This is the voltage with some load on the battery which reduces the voltage measured. You should measure it with a multimeter with the car in sleep mode to get the true voltage measurement.

[R2D2]

Originally Posted by TheDonGogoi

Hello, I am a new member to the TeamBHP community, glad to know your problems with the car have been sorted out. I would like to know about how we can check the system voltage on a BMW car mine is 3 series (G20) and it doesn’t get used very often, in fact only around 4K kms or so in the almost 2 years of ownership. I would also like to know if checking or opening the cars system voltage menu would cause any harm from the OEM side in terms of warranty or service.

You can check a digital multimeter and connecting the +ve probe to the charging point under the hood/bonnet. This will probably be covered with a RED rubber or plastic cap to insulate it from other objects. Please check your manual for the exact location.

This terminal is connected directly to the +ve terminal on the battery which in all likelihood is in the boot. Touch the red or positive probe from the DMM to the charging terminal and the other to any bar metal non painted part (bare metal important) of the chassis or engine block. You will get the reading. Make sure the car is switched off and idle for at least 3-5 minutes before taking a reading especially if you have been driving. This switches most vehicle electronics to a sleep or low power consumption mode.

[mikem]

Thank you both @R2D2 & @d3mon. Popped the hood, locked the car and checked the voltage using a multimeter on the +ve jump terminal (under the red slider) and negative on earth/body. Parked voltage was 12.1-12.2 volts.

Either way, I have asked my battery supplier to procure a DIN80 battery, AMARON Pro or AC Delco.

[Turbanator]

Originally Posted by Maverick5490

BMW M cars come standard with lithium-ion batteries, an AGM battery costs around 45k whereas the lithium-ion costs 1.2 lacs.

Wow, I was not aware though I was always intrigued about the capacity.

Depending on the type of my run, M5 will be running with radiator fans "On" for a good 2-5 minutes after switching off the engine. Another reason to get extended warranty.

[R2D2]

Originally Posted by mikem

Thank you both @R2D2 & @d3mon. Popped the hood, locked the car and checked the voltage using a multimeter on the +ve jump terminal (under the red slider) and negative on earth/body. Parked voltage was 12.1-12.2 volts. Either way, I have asked my battery supplier to procure a DIN80 battery, AMARON Pro or AC Delco.

@mikem, please consult the car's manual for the exact type of battery to be fitted. It most likely is an AGM sealed battery while the others you refer to above are flooded lead acid batteries. There's a difference in gas emission and charging voltages in these differing types. Also, your car's ECU may need to be programmed to recognize the new battery. That's how it measures expected life span. IMHO, this is best done at a knowledgeable mechanic or at the M-B dealer.

Yeah, AGMs are much more expensive especially those M-B supplied ones than normal batteries but all things being equal they can be less of a hassle to maintain + there are no emissions as the hydrogen is recombined with oxygen inside the battery to form water which the AGM reabsorb. This is what gives AGM that longer life and they don't require top ups. Best of all? If something goes wrong you have M-B's neck to catch and squeeze. There's no guarantee with an aftermarket battery fitment and suitability. There are plenty of lux cars owners on TBHP who may help you source a good quality AGM via the open market.

[BrakingBad]

Originally Posted by frewper

Also another alternative to hooking up your car to battery charger, (In case you dont have a power point near by) is that you can actually disconnect the positive battery terminal and the battery will hold power for two months easily. Only drawback is that the security system wont be working. But if you have secure parking, you should not worry

For simple cars, disconnecting the battery works wonders - I know my Father-in-law used to do this for his M800 and whenever we need to use the car, first thing we do is to connect the wires to the battery.

Can this be done for a prolonged period for luxury/complex cars? with so many of these luxury cars having the battery in the trunk, how hard or easy it is to disconnect the positive terminal?
Will it lead to system forgetting the seat memory and other preferences ?
There is a pain of doing date and time setup (happens for my Linea when we disconnect battery for some servicing)

Originally Posted by UP!!!!

Surprisingly my BMW 3 Series (~3.5 year old) just gave me a low battery warning when I started it after 2 months of idling. During these 2 months, it was cranked by my neighbour only twice for 5 minutes each time in the gap of 20 days.

I was very happy at the end and did not have much expectations from 3.5 year old battery.

Diesel Engines draw higher amount of current for starting as it ignites by compression. so if you just run for 5 mins and shut off, the current drawn for starting will be more than the replenishment in 5 mins. Ideally it should be run for longer time may be for 10 or 15 mins at idle speeds or take out for a spin for at least 10 mins... that way you will rotate the tyres and not keep the whole car weight resting thru one spot on each tyre for longer period. If i can't take the car out for a spin, I move the car for just one feet so the wheel is rotated a bit.

[vsaravind007]

Yes! German cars will go nuts when the battery voltage drops below a certain level. Its more prominent in older cars & in cars with slightly old batteries - same can happen if the battery terminal is loose or corroded.

Using a battery maintainer like the Bosch C7 is a good idea when the car is parked for a while. If the car wasn't a garage queen before & you parked it for a while, there is high chance that the car will go nuts! Daily driven German cars won't usually throw tantrums due to battery voltage(as the battery won't get much time to get drained), parking for a while is sure to make them go haywire! Some errors won't go away by driving, they will have to be cleared off with diagnostic tools even if its a false positive.