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I finally replaced the main battery on my 2011 GL450 today. I am amazed the original battery lasted so many years (date of manufacture 10/2010!!!) but it gave me some issues lately so I didn’t want to push it any longer with winter approaching. While I was at it, I decided to replace the aux battery as well.
I could not for the life of me figure out how to remove the aux battery from its metal cage. I watched a bunch of YouTube videos before I attempted it but none showed the original battery inserted the way mine is. Every video I watched shows the aux battery terminals toward the driver side, easily allowing the battery to slide out of the metal cage. Mine has the terminals pointing toward the right side of the vehicle and thus won’t fit to slide out of the cage. Trying to force it by bending the cage although easily possible did not help.
Anyone knows how to open that cage? I removed the bolt securing it at main battery floor area but there must be another one to the right of the unit at a place that is not visible. I didn’t have a small socket extension like a 2 inch to attempt it so I decided to give up and only replace the main battery. I do however want to get it done since it also is 10 years old.
Just Replaced My Aux Battery & Main Two Days Ago..A lot Youtube vids shows the aux Battery in the Reverse Position so the Terminals Are towards the Main Battery. But Mines Were in the Opposite Position and the Terminals were Blocked by the Metal Cage..
So to Get it Loose You have to Unscrew The Metal Cage there is a 10mm Bolt i think.. just unscrew and un-clip the Cage (The Clip is on the Other Side) and Removed the Battery just Remember to Put the Battery in With the Terminals Facing the Main Battery For Easier Access..
good Luck
Last edited by WaveyKat; Dec 14, 2020 at 09:49 AM.
Fwiw if it measures over 13 v with the main battery disconnected, it’s still good. My OEM mb branded aux battery was the original, when I replaced it still measured 13.1v at rest...so I didn’t really need to.
WaveyKat : Just as I thought. I took a photo of that nut (looks like a 10mm) and I assumed it holds the cage. I just couldn’t reach it with my socket extension, it was too long. I will buy a shorter extension piece. Thanks for the information.
Max Blast: Good info. I already installed the new main battery but one of the upcoming weekends I plan on pulling it back out to replace the auxiliary battery.
I pull that Picture from the Internet.. i should have taken Pictures when i replaced mines. yes you need a Short/Small Ratchet or Wrench to remove the nut.
Originally Posted by aggst1
WaveyKat : Just as I thought. I took a photo of that nut (looks like a 10mm) and I assumed it holds the cage. I just couldn’t reach it with my socket extension, it was too long. I will buy a shorter extension piece. Thanks for the information.
Max Blast: Good info. I already installed the new main battery but one of the upcoming weekends I plan on pulling it back out to replace the auxiliary battery.
lol I didn't even notice the fasteners on either side. I just bent the tab down and slid the battery out. Instead of a short extension, I'd use a wobble adapter for the socket.
However, even though we're both x164, I think my aux battery is smaller than the '11. FYI I got a compatible battery ('07), except the terminals are reversed, for like $12 delivered. The leads are plenty long and the reversed polarity doesn't hurt anything.
If you're wondering whether you need to replace the battery - don't worry, the dash display will tell you when it needs to be replaced. The truck will work just fine indefinitely with a weak auxiliary battery. A decent rule of thumb is probably to change the aux battery every second main battery change. Definitely synchronize the two; pulling out the main battery is a pain. Mine didn't fail until I moved to Idaho - 13 years after installation, and when the weather got cold. 13 years is about right for two AGM batteries.
I played a fun trick on my local battery store when I brought in the old one for recycling. I picked it up out of the back seat, acting like it weighed the 100+ lbs of the main battery. Good times.
Last edited by eric_in_sd; Dec 18, 2020 at 04:17 PM.
Just replaced both batteries last week. To make it easier, I removed the seat to move it around a bit. I did not disconnect any of the connectors, there was enough slack to move the seat around. It made the job much easier.
I finally replaced the main battery on my 2011 GL450 today. I am amazed the original battery lasted so many years (date of manufacture 10/2010!!!) but it gave me some issues lately so I didn’t want to push it any longer with winter approaching. While I was at it, I decided to replace the aux battery as well.
I could not for the life of me figure out how to remove the aux battery from its metal cage. I watched a bunch of YouTube videos before I attempted it but none showed the original battery inserted the way mine is. Every video I watched shows the aux battery terminals toward the driver side, easily allowing the battery to slide out of the metal cage. Mine has the terminals pointing toward the right side of the vehicle and thus won’t fit to slide out of the cage. Trying to force it by bending the cage although easily possible did not help.
Anyone knows how to open that cage? I removed the bolt securing it at main battery floor area but there must be another one to the right of the unit at a place that is not visible. I didn’t have a small socket extension like a 2 inch to attempt it so I decided to give up and only replace the main battery. I do however want to get it done since it also is 10 years old.
Any help would be appreciated.
just so you know, you do not need to make things overly complicated. All you need to do is remove the seat by unscrewing the 4 bolts. Then disconnect and remove the main battery. Bend the metal plate that holds the AUX battery in place with your hand to be able to slide/pull out. Then unplug the two wires from your AUX battery and using a flat head screw driver, bend the connections backwards to make them flat. Then pull the battery out just like pulling out a cassette from a vcr. Its hard to pull out but keep trying. Dont break a finger.
when you put the new battery , you will have to put it in the opposite direction because you cannot slide the pins under the metal slot.
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