I am going for an extended stay, 4 months away. Car will be in indoor garage. Is there any recommended things to do, such as starting and letting car run. How often should I start and for how long each time? Also, is there any other items too consider?

 

Recommend putting a charger on the battery such as the CTEK to maintain the charge state.

 

I second that. The car is awake, looking for an approaching key, an impact or a download, so battery discharge is really the only thing to worry about.
You'll get a "battery partially discharged" notice on your Mercedes Me app 8n a couple of weeks if you don't use a Battery Maintainer. CTEK is a good choice.

Regarding starting the car periodically - Don't!
Unless you bring everything up to operating temps, you'll be doing more harm than good.

Just get a Maintainer (not a "trickle charger") and you're good to go, literally.

 

Over inflate your tires a bit... when I store a car at one of our vacation homes usually inflate to max on tire... also battery maintainer.

 

On both of your keyfobs, press the lock button twice to "turn off" each key. This will help save the battery in the key fobs.

 

Great tip. Just learned something new.

 

This is very good advice. I thank you all for your input. The fob battery thing is a keeper!

 

Fill tires to max inflation pressure listed on the sidewall. Top off the fuel, add fuel stabilizer if you like and put the battery on a maintainer.

 

We leave ours for five months while at another house. In an air conditioned garage, We add a bit more air to the tires, put Stabil in the tank and fill it up, and put a CTEK batter tender on.

 

Have to thank all for your help!

 

Re: CTEK units do not use the model 3300. I have had several of them go bad and take out batteries. The newer CTEKs seem fine and that is what I use.

 

I store both my Porsches. Battery tenders and lift them off the ground.

 

put moisture adsorbers inside and if possible use a dehumidifier in garage.

 

Aren't they the same...?​​​​​​​

 

Nope. A trickle charger is just a low current, constant voltage charger. It can cook and damage a good battery if left on too long. A good quality battery maintainer will monitor the state of charge on the battery it's connected to and increase, decrease, or stop charging altogether as needed.

 

Aha, old technology: I thought every modern charger was "smart" with 3 stages and the ability to shut off as needed when the battery is fully charged,
Guess not.

I am using this one, a smart charger but they also call it a Trickle Charger..Marketing I guess.

 

I see that. Maybe a marketing thing as you said. The NOCO Genius is an excellent maintenance charger.

 

Holy cow, less than 1/3 the price of a CTEK https://smile.amazon.com/gp/product/...e?ie=UTF8&th=1

 

I have read that the battery connection is under drivers seat. Where would I connect to the battery? At the battery itself or another placement?

 

The connection points are under the hood. At least that’s where I connect my CTek.

 

That's the best place.
You will be charging the 12 volt battery, which in turn charges the 48 volt battery through a 12 volt DC to 48 volt DC converter.

 

Go to the Settings menu in your center screen and enter "Standby Mode" right before you lock the door for the last time