The battery is under the cover with the jump start positive connection. Pull toward you with the 3 semicircular finger grips.

After removing the cover use a 10mm socket to loosen and remove the battery negative (ground) cable.

Move to the fromt of the battery box and unclip the large connector. It has a locking clip that frees it.

Next remove the battery vapor purge hose through the hole in the center of the front of the battery box.

Use an E10 (female} Torx on a long extension to loosen front of the battery box, which covers the positive battery cable connections.

Move the large connector out of harm's way. Then completely remove the front of the battery box. Do not worry about dropping the hold down screw because it stays securely in the hole.

Remove and keep the red positive terminal cover to use on the new battery.

Use a 13mm socket to remove the positive cable from the stud on the positive connector. There is another 13mm nut connecting the BCM (the black box sitting on top of the battery) to a buss bar that can be removed at this time.

Now unclip the terminal on the BCM which is on top of the battery.Pull up the white tab to release the connector.

Now remove the positive battery terminal and the connecter BCM from the top of the battery.

Next use a 6mm socket to remove the nut that holds down the front of the pre-fuse box. Pull up the box and move it out of the way.

Firmly grab the left side of the battery box, wiggle and pull har to remove it. There are no clips, it is held in by friction.

The battery left side hold down can be removed with a 13mm deep socket. The deep socket is needed because the stud is too long for a standard socket to work.

The battery hold down strap is connected to th left hold down. Move them out of the way and lift the battery from the box raising the front end first. Reverse these steps to install the new battery.

 

Useful information.
Thanks for posting.

 

Wow all that to remove/replace a car battery that should be as easy as remove 2 screws.. Incredible. I hope those engineers got a nice promotion.

Thanks a lot for the detailed post.

 

That’s why I posted it. The stuff on the top is obvious. But the left hand battery bracket, which also holds the battery strap, is buried under 2 other components. Maybe save someone some WTH time. And 3 different size sockets are needed.

 

You saved me about $600!! Battery plus couldn’t do it for me, said they didn’t have the proper tools, but quoted me $350 installed. Dealership was $900. I ended up buying a battery from Costco for $169. Found your post and started the work. In my nature I just started rather than read your post and the tools needed. I was able to do it with the minimal tools I had. I was able to use a 7/32 socket to get the tork screw out. Thank god. But once I dismantled the battery, making myself unable to drive and realizing I didn’t have a 10 mm deep socket, it’s needed. Yes but I was able to use needle nose pliers and got that screw started. Removed it with my fingers. Thank god again. I would have never known how to remove that strap had it not been for you showing to remove that fuse box. Thank you. I broke the white clip trying to get that top part unplugged, so I left it and I’m I didn’t need to unplug that at all. I did it by myself in about 30 total minutes thanks to your post. If there is a charity I can donate in your name, reply to me. I really appreciate you taking the time to make the post.

 

Just a footnote to the above. It's always recommended to remove the battery's negative cable first and secure it out of the way. If you remove the positive cable first, it's too easy to accidentally hit a chassis point with your metal socket wrench -- something you definitely do not want to happen with the negative cable still attached. Installing the new battery, connect the negative cable last.

 

Good point, did I miss something?
But just follow the directions. Remove negative cable is step no. 2 because it’s under the case cover. Remove positive cable is step no. 8.

 

Agree, better safe than sorry. Thanks for the thread OP.

 

Thanks Odd Piggy! I could find very limited info on the internet / YouTube on this procedure, which looks much more complex than say for a GLK.

Questions please:

1) Given the complicated procedure & tight fitment, would you recommend an OEM replacement battery only, or any compatible brand name options suffice? How about Energizer from Costco - their website shows 3 options for GLB - Group H7, H6, and H5 - if they really all fit, the largest one seems the best given the minor price difference and the complicated procedure.

2) After installation, does the new battery need some kind of registration / programming, and if so any special tool is needed or can be done via onboard menus?

A service advisor at the dealership told me the current battery (production 37/19 in a 2020 GLB250) returned 40% "State of Health from Midtronic Battery Test" and recommended replacement, after which programming is required for the vehicle to properly recognize / charge the new battery. I was quoted Canadian $700 plus taxes (parts & labour), so exploring DIY as I was able to do for a GLK without much trouble.

Thanks again.

 

1) Any brand battery sized H6 or H7 should fit. Don’t get an H5 and an H8 won’t fit. The pics are of a Mercedes Varta battery in my wife’s GLB250 but I just put a Walmart/Sam’s Club Ever Start H7 battery in one of our GLAs. Mercedes battery $300, Walmart battery $180 (USD). Be sure to get the AGM battery.
2) I think there is a battery registration procedure you can do if you have a scanner. I haven’t found that it helps extend battery life and haven’t bothered with it since around 2003. Others may disagree with me on this.
-BTW An H7 battery weighs 62 pounds and you’ll be working with arms partly extended, so be prepared for that lift.

 

I think it's a hustle.

 

Thanks Old Piggy! I checked my records and it was an Energizer H7 AGM (from Costco) that I replaced in my GLK previously. Was heavy but manageable, so would go for the same for the GLB. Costco is listing the battery at Canadian $320 plus taxes, so looks like DIY saves almost $400 vs getting it done at the dealership (OEM battery) for $700 plus taxes.
Costco offers 5 years limited and 100 months prorated warranty on the Energizer AGM battery, so I suppose in some way mitigating the risk of skipping the programming as I don't have a scanner!