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2016 GLA250 4matic
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Discussion Starter · #1 ·
Hi Folks,

Happy Thanksgiving to everyone. This is one very memorable T'giving for me as I couldn't start my GLA for the first time since I've owned it (Mar '20). Well. I sort of could but then couldn't again. Allow me to explain.

Last night I drove home from work and screen displayed "Blindspot Assist Inoperable" upon engine starting-up. I never saw this before but after one errand stop, display never showed message again and amber yellow triangles disappeared from side mirrors. So all was good, I thought.

Went home and put GLA on Battery Tender (which I use frequently).

All of today while GLA was sitting in garage, Battery Tender light lit up green as expected. As I tried to disconnect BT from GLA (but not quite detached), BT light turned to red, which was strange.

I got in and couldn't start engine using keyless. I could tell it attempted & struggled to but to no avail.

I inserted the key manually into slot and succeeded in starting its engine. I let it run for 10min, manually switched off key, resumed to start it (manually) but couldn't succeed.

It's now sitting at my garage with BT re-attached. If I manage to start it again tomorrow, is it safe to drive to my dealership 25 miles away?

And if not, any special instructions I should give AAA apart from using a flatbed?

Thanks in advance for all your help.

Hope your Thanksgiving was much more enjoyable than mine...

Ed
 

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Once started you should be safe to drive but ... if the battery is flaky with an internal short you could suffer voltage variances that could affect sensors and cause problems. Swapping the battery is easy requiring just a 10 mm wrench (to remove the cables) and a 13 mm socket with extension and ratchet handle (to remove the lock down plate). The battery has handles to lift it but it is fairly heavy. Otherwise you're right about the flat bed.
 

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2016 GLA250 4matic
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Discussion Starter · #3 ·
It was the main battery. Battery Tender gave me the false sense of security all this time when battery read only 10+V when idling last night. I distrust BT from now on. Also, would it kill MB to give me a message of "low voltage detected" before it quit on me entirely? What if I got stranded on a remote locale under blizzard condition?

Nevertheless, happy that issue is resolved now.
 

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We had the same issue about 6 months ago (MY2015) ~115,000 miles. I replaced the battery and it fixed the issue temporarily. If it happens again, it may be the starter. It gets a lot of wear and tear restarting the engine multiple times throughout the drive.
 

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Discussion Starter · #5 ·
We had the same issue about 6 months ago (MY2015) ~115,000 miles. I replaced the battery and it fixed the issue temporarily. If it happens again, it may be the starter. It gets a lot of wear and tear restarting the engine multiple times throughout the drive.
Are you referring to the Start/Stop function? I always disable it under ' I ' drive mode.

So during your ownership of the GLA, how many main batteries has it gone through thus far?

I'm thinking of installing an onboard WiFi battery monitor to keep an eye on it.

And how come A service doesn't include battery check which was done 2 weeks prior to incident? Or was my indie garage slacking? Does B service include battery test?
 

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Yep. If you're disabling then it's probably still good.

We replaced the 1st battery because it was causing transmission issues. Dealer wanted $600 so I got an aftermarket for around $150 and installed myself. It was just outside of warranty and never tested during services apparently. We're on battery 3 but the 2nd battery still had some life left. It was approaching the warranty expiration date so I swapped it out for a new one because I assumed it was the culprit. Car started right up for two weeks and the issue arose again. Indie mechanic diagnosed a bad starter.

Battery check isn't a part of either service according to the maintenance booklet. And checking the starter is only for the E and S class. Go figure.
 
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