Two things (from a technician): 1) The positive terminal ALWAYS goes on first when changing any car battery. Ground terminal is first off, last on. Once the ground is off, the positive terminal can touch anything, without consequence. 2) You forgot to plug the vent hole on the positive side of the main battery. If you look again at the video, you'll see there is a small red plug attached to the corner of the red safety covering that was on the positive terminal of the battery when you purchased it. You are supposed to break that little plug off and insert it into the vent hole on the other side of the battery. The battery has vent holes on both sides for use in other applications. Failing to use that plug can result in battery gases escaping into the battery compartment rather than being vented outside the vehicle.

Great helpful video. Your 11 years old son did a great job recording it!

Nice job, man. Very helpful video. I love working on my GL 450 but sometimes it drives me bananas. This is helpful. Good delivery and good realistic advice.

Thank you so much for this video I couldn’t for the life of me figure out why my car has went crazy !!!!!

Thank you so much I just bought a 2008 GL 450. I hope your is still running strong. I pray I I bought a good one and not a donut.

Liked how you bring your son along so he can learn how to do it , I did the same with my son 👍🏼

I have a 2010 GL 450 and I’m finishing my second aux battery replacement. The first was 3 years ago and it was an incredible pain because I didn’t think the tab holding the battery in was designed to bend, so I removed the cage, which took me 4 hours to remove and replace because the nuts are almost impossible to replace. DO NOT unscrew them. Just bend down the tab and pull the battery out. Also, don’t pay Benz $35+, go to Batteries and Bulbs and get a Duracell AGM for $14.95. My symptom has been door lock solenoids randomly clicking and/or refusing to lock automatically. My first replacement battery died because the car was garaged for a year and a half due to a bent drive shaft I couldn’t afford to replace. The battery went completely flat,

Great video! The only thing I want to point out is that you may want to tell your viewers that you disconnect negative out first and positive 2nd. When reconnecting, it’s positive first and negative 2nd. Again, thanks for the video!

Thanks for this video man and link to each battery 🙏🏾🙏🏾

This was helpful in replacing the aux battery causing my rear breaktail light and license plate light from staying on. My tip is use good gloves when doing this if you don’t like getting cuts....btw, I took the main battery to Autozone and they tested it “good” but needing a little charge. I had a trickle charger on for a few days but could not fully charge so I think the aux battery was the problem that was draining the main battery.

I'm currently doing it using your video thanks a lot!

Great video, very helpful

Great video helped me out massively here in UK. Just a minor point at 09:43 you meant Amp hour not Amp henry

Very thorough thanks

Awesome Video, Just did the Aux Battery on my W164 ML500. Like you just did, you didn't have to take out the Aux Cage. Just Bend the Tab the Aux battery slides out. Just to make pulling the battery easier, I unbolted the seat (4 Torx Head) and put it forward. Didn't disconnect anything and didnt require and recoding.

Great job

there's another aux battery in the back as well, correct? ive been having battery drain issues so i always make sure to unplug my main battery after i shut my car off, but all of a sudden my ISM isn't working and my truck is stuck in park, so I'm thinking the aux batteries have been completely drained by the drain problem, and that's causing my ISM to malfunction. going to try replacing them both today, I'll let you guys know how it goes in case anyone runs into the same issue

Costco’s version of the battery is by interstate with 900 CCA. Its model number is H8(49)

Great 👍👍👍👍👍👍👍Very helpful video. Thank you so much.

hi, thanks for the video. i recently purchased a 2012 GL450 and sometimes the turn signal lights doesn´t work and the rear hatch never work properly, i replaced the rear hatch hardware and doesn´t solve the problem. now looking into your video see that the battery could be the reason but when i purchased the SUV the previous owner told me that changed the main battery for a new one so this is wondering me 2 questions: how could i verify if the main and auxiliary batteries are good? and if these are good what would be the reasons of the malfunction of those parts?, thanks in advance.

You connect the RED/Positive first. Nothing will spark with ground off. Good duck tape trick with the wrong size 14mm socket to hold nut in socket. It's 13mm nuts, and you want to make sure battery is push into front hold down. Defiantly recommend AGM batteries.............

I noticed the positive cap still has that airhose circular plastic cover for the other hole, do we have to cover that or can we leave it open as long as there is an air hose on one side? Thanks.

Thanks for the video. I have a 2012 GL450 and this video was very helpful. Quick Question: I purchased the same batteries as you suggested. After installing everything, when i turn on the car it says "auxiliary battery malfunction". I am surprised that a brand new battery could be malfunctioning. Do you think I might be missing something ?

Is there anything you have to do as for reprogramming? Or is it fine when restarting car? I'm glad you did this video I have to do this and had no idea about the back up battery

can you move the seat if the battery is dead (it wont even unlock ) so i can remove the battery and charge it (the vehicle is outside and i cant charge it there and moving is out of the question cause it locks wheels and everything

Hi, thank you for posting this video. You explained the process very clearly. You seem to be a professional mechanic. The video does help me a lot. I have same model Mercedez. I recently found out water got in either from sunroof or the hood. The battery tray was almost full of water. The car won’t turn on, right parking light and fog light are on and flashing. Dashboard shows battery is out. I tested the main battery and it is good. Can you please tell me what the auxiliary battery for? Thank you!

Ah means amp hours, not amp Henry’s. Henry’s has to do with inductance and is denoted by the symbol “H”

Does a Mercedes GLS also has an auxiliary battery and where is it located

Could this eventually cause a no start

Where can I find the system loader

How did the mini Duracell hold up? I really try to stick to Genuine/OE but they have both of the ones you used here in town. I saw someone on Amazon say they bought an aftermarket auxiliary battery and did not have good luck. They did not say if it was a Duracel. I actually kinda like the idea of having a Duracel in my GL hahaha. Kinda cool. I do not think the big battery is available as a Mercedes Genuine part anymore anyways. Hoping you see this comment. If anyone else used the Duracel and sees this lemme know! Thanks for the video I think I am going to try and do this myself. I even have the trim tools already haha.

Where can I find the loader

Friend asks I put a new battery ok if it has a delay when turning on a delay of 3 seconds it can be the auxiliary why the new battery is pulling well it throws 13.7 and 13.8 it must be the auxiliary answer me as soon as possible

Did u leave the driver's door open to keep system from needing reprogramming?Or connect power source to positive and negative terminals to keep system from being compromised and needing reprogramming?

Did it work?

Great everything on my ML350 2008 is working except for the back sore lift gate it won’t open automatic I have to pushed hard Can I disconnect the battery negative to reset the system??

My GLis slow to turn over. I have over 95,000 miles. I think it is time for a new battery.

Can you hook up amp power cable to auxiliary battery ?? Does it make a difference?

I’m having trouble with my hatch lever not flipping back... I have to manually flip it back and then the buttons work to close it. I just had a new system battery put in, but not a new auxiliary battery. I also never got an error message stating the auxiliary was bad. Do you think the auxiliary battery is bad, and would that fix my hatch lever problem?

Hi, thank you for the video, it's very helpful. I followed your instructions and replaced my battery. Unfortunately, I skipped the air vent detail and installed the battery on the air vent hose and it broke. I got a new air vent hose but wondering where the other end needs to get it. I appreciate if anyone can help me. Thank you

Duracell batteries in Mercedes GL450 have problems holding a charge. You will definitely have a shorter life span on that auxiliary battery

thanks, nice info but I will also add a 12 volt to the leads so I don't lose my programming while replacing the batteries. did you have to cut the rug on the right-hand side to access the batterie easyer.

Great video very helpful did everything under 20 mins.Now my question is my radio/windows, radio is in nighttime mode and it’s set on automatic also my windows go down automatic but when I close them I have to do it manually and when they do close it goes down by its self half way. Also I didn’t change the Aux battery only the primary is that the reason why??

johnson controls + high quality shizer

What was the spray you sprayed on the terminals at the end?

Having same symptoms as you were. Pulled batteries and had tested. They said batteries were good??? Charging them to see if they take charge. I let my car set up for several months. That is when I noticed problem. Thanks for your video. Any input would help.

How long do you have before everything is erased (codes) before you install either of the batteries back in? Say the radio code? I have a x164. 2010 gl450

Do you need power bank back up battery before you remove main battery thank you?

Do i need to worry about the memory of the radio or the electronics messing up? I took my car to Pepboys and the guy was concerned about it loosing memory and he said they needed a memory stick so it won’t hav e any issues

How did your batteries holding up?

Another video said you always disconnect and reconnect the positive connection first. He said that is very important, but you did the negative first... Why would he say that, and test you do the opposite, and it didn’t seem to matter.

thinking of buying this exact truck....any issues for this year or pretty reliable?

Hi everyone. My stereo system works when i start the car. After 1 min and 45 sec sound is stop. signal works, stereo system's screen is on everything is works. my original amplifier is just replaced last year with oem one. when im parking the car after couple hours attempting to start engine i can listen the radio. but after 1 min and 45 sec sound is stopping again. is that possibly aux battery? (2007 gl450) cos when this start we were in artic cold effect in NY. Edit: also when this start happening also i had licence plate light message was on my dashboard. my licence plate light has been replaced 3 months ago. hopefully aux battery caused all that.

That's stupid where the battery is located

Is it ok to use H8 out of Walmart!?

You forgot to hook up the car to a 12V power source to keep the juice flowing to you on board computer - as a result you will now deal with reprogramming all your system from scratch -that might require a visit to your ($) Mercedes dealership

AMP HENRIES!!!!

C t

Too much work for a fucking battery. Dump the Mercedes and get you a chevy truck.

You waste too much time helping to locate the battery. Do another separate video talking about battery quality

Great video, very helpful