For AGM battery, there's not much difference between the charging method, but when it gets to trickle charge mode, you'll want to lower the voltage to 13.8V max instead of keeping it at 14.4V. That's probably why some charger has a selection switch as OP mentioned in the first post.

 

Ha Ha Ha... what a dumb thing to say. Our dealerships has solar cells in the windshield of the cars on the lot to keep the batteries topped up and inside the showroom they have a portable battery charger and a book called 'Battery Charge Log' to keep the batteries on the showroom cars topped up.

OF COURSE the batteries are rechargeable, what other kind of car battery does he think there is???

One of the best things to do is take it out and drive it on an extended drive. I might do some 'battery charging' on my wife's car tomorrow!

 

That's true with the headlights or interior lights and almost all other accessories.

It is not true with the parking light/s which will remain on until your battery is dead, dead, dead. It's easy to miss that it's happened inside a well lit garage. On mine, if headlights are switched on when car is shut off, the headlights switch off and parking lights are on. Easier thing to happen (headlights off) is if you bump the turn signal up or down (when getting out) it will turn parking light on for either left or right side (depending on which way TS was moved).

I've had it happen twice. First time was after the car was a week old, phoned the selling dealer (Closest was 150 miles away at that time) and they had no clue how my battery could possibly be dead, so I just charged it back up and all was well for many years.

Second instance was just over a year ago, had replaced with new battery (just on the fact that the original was five years old and I did not want to be surprised by a failure) three months prior to this incidence. It was so dead that even jumper cable from fully charged Boat Battery wouldn't start it (perhaps my jumpers were too old). So charged it again, but all I had this time was a tiny 1 ampere charger, so it took all day and overnight. I've bought a new charger and it has the choice of AGM or Gel Cell along with 2A small 6A medium or 10A large. It is my opinion that if you can spare the time, lower charging rate is better.

I've also bought a Cobra JumPack which will (USB) charge your cell phone, Tablet, etc. many times or will Jump Start an automobile three times if the JumPack is fully charged.

Fits nicely in a rear seat side storage tray, just don't hide it in the boot, as MINI (Cooper at least) no longer come's with that emergency pull cable under back seat to open the boot when battery is dead.
Art

 

I've tried 3 different smart chargers: Noco Genius, Battery Minder, and CTEK on the Mini's AGM. All chargers were able to fully charged it.

I think only CTEK has a dedicated AGM setting though.

I've also read somewhere that you're supposed to replace the start stop battery with another AGM because of the different charging setting on the car's computer.

AGM are expensive, so take care of your battery and top it off with smart charger regularly if you don't drive the car much.

 

Yes, it is actually an AGM battery because of the start/stop system.

 

That doesn't even make any sense. BMW use a regular starter for the start-stop, it's not even anything special. Hybrid cars with IMA or eCVT use NiMH, LiIon, and LiFePO4 batteries and they all re-start the car just fine. Not to mention you can turn off and on any car with a lead-acid for the past 100-ish years.


I'm not sure how the OP actually drained the battery as the lights will all turn off via their respective timers. Nevertheless, disconnecting or otherwise under-volting the car means you have to get it to the dealer for a "reboot" of sorts. Leave it to BMW to make the battery setup much more complicated than it needs to be.

 

I had AGM's in my bass boat and they were being recharged after each outing. So clearly the dealer stating they cannot be recharged is not from this planet.

Seems like all new cars with their many electronic internals will drain a battery to a point where the car will not start if left for a long period. That length of time has been hotly debated on a number of forums. On the C7 forum, some guys were saying a week (which would make no sense at all IMO).

A reasonable guess would be a car should last at least a month parked, and still have enough juice to start the car without an issue. Since we know the MC battery is AGM, most chargers have a setting or will automatically detect the type of battery connected and will will charge with the correct voltage.

I haven't checked, but what brand of battery is installed in the MINI? Most new car battery's have a years (more likely 36 month) warranty (free replacement within first year, pro-ration involved from 13 months out). In Florida, we are lucky to get three years on our car batteries. So any replacements I buy usually have a much longer warranty than what normally come from the car companies.

I've had great luck with batteries sold at Costco. Costco had/has a 72 month Car battery w/ a 36 month return policy (full price minus disposal fee) if it fails. Their batteries are made by Johnson Controls (who also makes the Optima brand).

Most auto batteries are made by just three manufacturers, Delphi, Exide, and Johnson Controls Industries. Johnson Controls makes Diehard (Sears), Duralast (AutoZone), Interstate, Kirkland (Costco), Motorcraft (Ford), and some EverStarts. – Source Consumer Reports

 

All cars have what's called Quiescent current. It's the minimum default current draw on the battery when the car is "Off". This powers the immobilizer/security system, RKE, volatile memory [clock], and car depending GPS/communications.

As such, every car will "last" while stored a different length of time, but a few weeks is typical. It's important to match the batteries useful [not just advertised] capacity [in Amp Hours] to the vehicles quiescent current to ensure the car can sit for the desired number of days.

 

Is there a BCI Group number for the correct replacement battery for the F56 MCS? I guess a replacement battery would be a dealer warranty item, but maybe I'd consider an upgraded battery - in the correct size.

 

Pic of battery thanks to RYE
See if it comes up.


https://farm1.staticflickr.com/634/2...b732645b_c.jpg

 

I plan to store my JCW for 6 months once the snow starts flying. Storage location has no power. Guess I'll have to drive it once In a while. Sucks.

 

Here you go.
IMG_7427.jpg by Ryephile, on Flickr


As for the "no-power" storage; do you have access to the sun? Make a little solar panel power supply to feed power to a battery tender. Would be a fun little project.

 

Is there a BCI Group number

 

There is a solar powered battery tender. Not sure my storage facility would look kindly on me mounting something on the roof.

 

It wouldn't hurt to ask. Or on the door, if it's sun-facing. 6 months is far too long to put any car away; things atrophy in a hurry. Your winters can't be worse than ours; later December, January, February, and maybe early March is about all that a car deserves to be hid from being driven.

 

I got me a rather large Black and Decker jump battery. I used to store my '08 for 5-6 months. Not enough juice to start, had to use the jump pack. Drive it around for an hour, check the fluids, make sure the tires have the right amount of air and you were good to go. I usually brought it in right away after bringing it out of storage to get its service done. Never had an issue.

 

Sounds interesting, will have to look into it further, my unit gets sun for about 2/3rds of the day should be able to mount something on the door.