Battery charging AGM mode & key fob issues

[M30LEV]

I know there are a number of topics on this subject but after not using the car since November, one short run in January the car is left unlocked in the garage and started ok but when I got to my destination some 20 miles the key fob would not lock the car I sat in the car and pressed the fob about 4-5 times and it locked and unlocked ok. But think if you don't use the fob for a period of time, does it need re-programming to the car. This made me think is the car battery going flat purchased a ctek MSX 5.0 and a CTEK comfort indicator as soon as I wired it in it flashed RED battery definitely needs charging. On the charger do I use the car mode or AGM mode to charge the battery. Car is 3yr old coupe 15k miles. Thanks all.

[Ftypeharv]

May be worth just trying new battery in key fob, I had similar issues.

[PussCat]

The standard 12v battery on the F is an AGM. Mine is. AGM mode on the CTEK is the one to use.
I'm not at all surprised your voltage was in the red zone, mine spends most of its time there.

[simpleR]

the car is left unlocked in the garage

Surprised battery wasn't completely flat. If you double lock the car it will go into sleep mode.

Presume your key fob battery is flat as well.

[M30LEV]

If the car is not being used is it best to lock with a double press on the key fob to go into sleep mode. I guess this powers most of the cars electrics down if not being used for several weeks / months.

[chicb]

My F type is hardly used, sits in the garage unlocked with Ctek on. It can be left on for months if need be. Starts first time. Comfort indicator is a waste of time. Even if its fully charged, if you switch off Ctek, it will flash red. Go by lights on Ctek. Battery charged when all yellow lights & first green light is on. From memory, its fine to start after 4 yellow lights are on although it seems to work with 3 yellow lights on. If you leave it on for around 5 days the second green light will light up. Ctek has then gone into battery management mode where it allows the voltage to fluctuate then brings it back up. Ctek is not like old fashioned battery charger but is a battery conditioner. If you allow your battery to fully discharge ie. dead, you will have to use an old fashioned charger to put some voltage in before swopping over to Ctek which should then revive it.
Your key fob battery sounds as though its on the way out. The key battery should be changed by the main dealer at service time although it lasts for a couple of years. I usually find they leave another battery in the car for the second key. It does not need re-programmed. I suspect lots of dealers don't bother changing it.

[scm]

The key battery should be changed by the main dealer at service time although it lasts for a couple of years.

Really? It's a 5 minute job (and a lot cheaper!) to change it yourself. Just follow the simple instructions in your manual. And, in my experience, they last a lot longer than a couple of years, especially if you have keyless entry and don't use the fob to unlock the car.

[chicb]

I have never asked them to do it, they just do it. Service plan, so no charge to me. Lasting for a couple of years is a throwaway remark, not definative