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Hello everyone! So I got into my 2011 ML 350 a little over a week ago and trying to be proactive, I've decided to give a car a once over. Set my schedules for upcoming maintenance and such. I did notice that every time I start the car, the volts read 11 and something (11.4, 11.6 etc. Sometimes even in the 10 range.) I've read enough to know that this is not good. In fact it should be dead from what I read and yet the car started albeit with a sluggishness that was not very inspiring. So after a week, I decided to switch out the battery. Got one that was reviewed well; did the DIY and found a AAA battery under the seat. Figured it died at some point and AAA had to switch this out. They did put in a AGM battery which was good but there was no date sticker or stamping to tell how old the battery was. Completed the DIY fully expected all the numbers to be above 12.4 volts or so and to my surprise the next morning, it read 11.5. Did I just replace a perfectly good battery? Is this a thing for our ML's? Or is there a parasitic draw that took this new battery right down? This one was stickered 2/21 so I'm assuming it's only 2 months old; then again, it is a sticker. Anyone have any experience or thoughts? Appreciate it mates.
Hello everyone! So I got into my 2011 ML 350 a little over a week ago and trying to be proactive, I've decided to give a car a once over. Set my schedules for upcoming maintenance and such. I did notice that every time I start the car, the volts read 11 and something (11.4, 11.6 etc. Sometimes even in the 10 range.) I've read enough to know that this is not good. In fact it should be dead from what I read and yet the car started albeit with a sluggishness that was not very inspiring. So after a week, I decided to switch out the battery. Got one that was reviewed well; did the DIY and found a AAA battery under the seat. Figured it died at some point and AAA had to switch this out. They did put in a AGM battery which was good but there was no date sticker or stamping to tell how old the battery was. Completed the DIY fully expected all the numbers to be above 12.4 volts or so and to my surprise the next morning, it read 11.5. Did I just replace a perfectly good battery? Is this a thing for our ML's? Or is there a parasitic draw that took this new battery right down? This one was stickered 2/21 so I'm assuming it's only 2 months old; then again, it is a sticker. Anyone have any experience or thoughts? Appreciate it mates.
Cheers
A few questions:
Diesel or gas?
When do you read the values? When the car is off, running, or cranking the starter?
What tool are you using? Scanner (which type) or multimeter?
Where are you measuring? At the battery terminals or under the hood?
A few questions:
Diesel or gas?
When do you read the values? When the car is off, running, or cranking the starter?
What tool are you using? Scanner (which type) or multimeter?
Where are you measuring? At the battery terminals or under the hood?
1. It's gas
2. I read it at all three stages.
3. So I'm not electrically inclined but I took the reading while the car was keyed in the ready/ACC position and hitting the "R" button 3 time to get into volt menu. I also have a FM Bluetooth device that tells me the voltage when it' first turned on. Both were about the same consistently.
Included are some pictures.
Picture before turning over this morning. I was pleased to see this as usually it's in the 11.something range.
Bluetooth device show the same ready more or less.
This is good. I noticed it drop to 13.4 when I accelerate from stop but then quickly goes back to 14.1
It's just those weird 10 readings. Now that Bluetooth device is plugged in all the time but it does power off after a bit I believe. The 12v access next to the passenger side is also used for my USB devices and that's usually left in as well. That turns off as well after a bit. If they stayed on all night I can see that as a problem. Maybe I'm wrong? Cheers.
All good ways to measure voltage. On mine (a GL) I have noticed that the cluster voltage display is .2V lower than at the terminals. Just FYI. I observe mostly using a scanner too, unless I think something is not right with the values.
Re: accessories turning off. Im not familiar with the ML passenger side 12V outlet. Is it in the foot well under the glove box like the GL? If that's the case, it should turn off shortly after you turn the car off and exit the vehicle like other accessories (heated seats or command). Going by what mine does currently (I have a dashcam/GPS connected so I monitor it constantly), it will sometimes stay on after I exit and lock the vehicle. I've noticed it would be still on after 30 min. If left longer, it would take up battery juice and possibly drain the battery overnight. And sometimes it will turn off as designed/intended. It would be worth to remove the power to your USBs from the 12V and see if that may consistently give you the ~12.4V before start.
Your BT is connected to the cig lighter. If you're sure that it turns off, that's good. I know that the OBD2 port remains powered when the car is locked. I have an MBII scannet which I sometimes plug in when I'm driving around to observe live values. If I lock the car and walk away, when I return, the scanner is still powered up. My scanner doesn't need outside power source, it draws it from the ODB2 port. Maybe your BT module in the ODB2 port is drawing power overnight as well? It doesn't need to transmit ibut
just being plugged in might be making a difference. I would disconnect it as well to test.
Update: This morning, checked the voltage and this showed up
I'm hoping one of our electrical wizards on this forum could explain why this would show up. Mind you, the car starts up fine. Cheers.
A few questions:
Diesel or gas?
When do you read the values? When the car is off, running, or cranking the starter?
What tool are you using? Scanner (which type) or multimeter?
Where are you measuring? At the battery terminals or under the hood?
Volts aren't a linear measurement, you can disregard.
If you're seeing a drop in voltage, you must have something draining the battery. Did the drop occur overnight?
I would remove the ODB2 attachment under the dash and unplug anything from the power plugs. Also check in your glove compartment and remove anything you have connected to your MMI Plug (if you have one there, I'm not sure if the ML does or not). Then test/measure again the next morning.
If you have a trickle charger, top up the battery. Drive the car as usual and check voltage, over a few days, but don't leave anything plugged in the accessories power sources.
Just thought of something else. How close do you keep the car key to the car when it's parked at home? I read somewhere that if it's too close to the car, they continuously communicate and that will have an effect on the battery voltage level. As a side note, you do not want to leave or forget your car key in the car overnight or you'll have a dead battery in the am.
Just thought of something else. How close do you keep the car key to the car when it's parked at home? I read somewhere that if it's too close to the car, they continuously communicate and that will have an effect on the battery voltage level. As a side note, you do not want to leave or forget your car key in the car overnight or you'll have a dead battery in the am.
Fascinating. I'm 3 stories above so I should be free of that issue but...... nice pull! Cheers
I have several cars with AAA batteries and there are some very odd AAA policies. If you remove the battery yourself it voids the warranty. If you take it out of the car, make sure that you charge and reinstall it as left before calling AAA. They have records on the battery replacement date, but it must be purchased by you for warranty service, and is not transferable to different AAA members. Make sure that you confirm they have installed the correct size battery and post orientation! Yes, they can get it wrong and I have experienced it!
E Coupe C207, ML W166, ML W164, Sprinter 1500/144, W111 SB220 Fintail(s), A5 chassis Beetle 5+5
I changed my battery and it wasn't difficult. AUX battery saved all my settings. Old battery was hovering at 12v, with slow cranking. I used a lead acid battery, I like them instead of AGM. Everything works a little bit quicker and better.
04-13-2021 | 11:36 PM
