I have GLE350 2016. Battery is at 50% of capacity now. If I wait until battery completely dies and replace battery (I do have jump start battery), does car needs to reprogram if it lost power due to failed battery? I heard many modern cars cannot have battery disconnected for long time. Since GLE350 (2016) is the same as ML350, I assume it would be ok if car doesn't have any power?

First I dont know the answer to your question. Next is you need be familiar with how to jump start the car. ( the posts are under the hood) I have a 2015 ML350 with original with original battery. I use a trickle charger (CTK something) for my Mercedes. About once a week, I open the hood up and attach the charger. It always charges the battery to 100% . Currently when I hook up the charger, it shows about 25% on the charger. This is just something I like to do. (See how long the battery will last). My wife is not happy with this game Im playing. I just hope it never leaves her stranded. She says, I like living on the edge.

My GLE350 2016 has original battery, too. I think your car is probably one year older than mine. Since this is the car I am driving (not my wife) and battery is expensive compare to other cars, I'd like to see how long it lasts before I really need to get a replacement from Costco. I do use CTEK charger when I only drive short trips once a month to full charge the battery. I have a spare battery jumper in the car in case car battery gives up and need to jump start. I heard some people were saying some luxury cars you cannot disconnect battery because alarm or computer systems will reset and need reprogram if power is completely out. I just want to find out what I should be expecting if some day battery really dies. I don't want to have any surprises if jump start doesn't work since this is my first Mercedes and still learning German engineering.

I did found out that GLE/ML has a second battery called Auxiliary Battery. When primary battery fails, second battery will supply power. So in order to have a complete power failure, BOTH battery need to fail. However, they probably both have same life time.

Being a new owner of Mercedes, I have to say that Mercedes doesn't design the car for owner to replace battery easily. Primary battery is under passenger seat. Auxiliary Battery is under second row seat(need to remove back seats to reach Auxiliary Battery). Labor cost to replace the battery is more than battery itself.

Just had to replace mine. Got a higher capacity AGM. Yes, there needed to be some reset procedure done. 50% is considered to be no good (especially for stop/start function.

No. No reset procedure is required.

Replace the battery now. It’s worn out.

Buy the new battery from the dealer. It’s expensive. You accepted this when you bought an expensive German luxury vehicle.

Thanks! You have very good DIY steps on maintaining GLE including replacing both batteries. Awesome stuff!

My car doesn't have stop/start function. I am not worry about car stops in the middle of each trip.

Greypoint01,
Some of your assertions on the batteries are not accurate… please search this forum for lots of good information on what the 2 batteries do, what type…, etc…
for 1 example, the aux battery is not a backup to the main battery and will NOT power the car if the main battery fails.
Be well!

X2 on ne need for any reprogramming.
Unlike older models GLE keeps all the memories, including garage door opener.

At AutoZone the battery is around 230 with 3 years warranty they also install it.