Car Dead Battery or Electronic/Electrical issue?
 

I'm in need of advice and/or a dependable auto mechanic for a 2015 Benz with 81000 miles that we've owned for 7+ years . My expensive 3 1/2 year old Duracell AGM battery goes dead about a day and a half after charging and starting a few times in the garage. I'm not sure if there is an electrical drain or bad battery. I was able to check all the fuses, except for 4-5 (under the hood) with a multimeter, which I couldn't reach the first try.

I've always worked on my own vehicles, but I'm no electronic/electrical guy. I only found out yesterday how to use my multimeter just enough... to check the fuses, lol. Have you ever heard the saying, " I drive it till the wheels fall off"? Well that's me!

Any suggestions would be very much appreciated.

And thanking you in advance.

From what I have heard, 3 years is about the limit on these batteries. If you are able, charge the battery, then remove it (or drive to) Advanced Auto or one of the other auto parts stores and have the battery tested. I recently had a conventional sealed lead acid battery tested. All of my tests indicated it was OK, their test showed the cranking amps were only 150 and should have been 750 amps, I got a new battery as this one was under warranty.
As for a possible drain, I have never heard of one draining a battery this quickly, but if you can use a digital ammeter you can disconnect typically the negative lead on the battery and insert the meter and see if you have current flow. If you have a significant flow (above 200 ma ?) then you may need to start pulling fuses one at a time to see what is staying on.
IMHO, I really think you have a bad battery.

Light on?
 

Great advise from villagetinker. My sister's car had this problem once. The trunk light was staying on. You can look for obvious things like that. Check your done lights, etc. If you can't tell if trunk light stays on, you could remove the bulbs and see if there is any improvement. Another idea, you could put you iphone video camera on and close it in the trunk.

Simple cheap tester with tell you the exact condition of battery. Answer simple questions the tester asks.

ANCEL BST200 12V Battery Tester 1100CCA Car Battery Analyzer

Or similar and shop around for better price. It takes little to no skill to read the results.

I also have the antiquated load tester which dinosaur compared to electronic version.

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AGM batteries are supposed to last longer due to separation of plates with barrier and no liquid I would expect AGM better to last twice as long as lead acid battery or what’s point buying one?

“ An AGM battery will cost more than a regular lead-acid battery — but it'll last longer and save you money in the long run. They last longer than regular batteries. Because they don't have any liquid inside them, AGM batteries have fewer components to fail, so they last longer than traditional car batteries“ quoted ‘. Not my words theirs.

Warranty information two years? I’d I read it correctly IMO that joke for extra cost.

AGM Batteries: Warranty - Go Power! - powered by HappyFox

Can I replace AGM battery with lead acid battery?

Can I Replace an AGM Battery with Lead Acid? | RealTruck

Advance auto will test your battery for free. 3 1/2 years is a lot for a battery in Florida's heat.... Most likely your battery is at it's end.

It may have died a premature death. My automotive AGM batteries have lasted between 6 and 9 years in southern GA and FL. Perhaps there is still some warranty remaining on it.

I am on my third AGM battery in 7 years, with 60K miles. They cost about $300. My vehicle is always parked in the garage.

Short trips and extreme heat will kill a battery in 3-4 years, especially the short trips
because the battery doesn't have time to come to a full charge.

Driving in Florida has some draw backs like brakes.
I use to get 80-90 thousand miles on my brake pads up north.
Down here with all the stop and go, slowing down, and stop lights, I need new brakes around 40 K.

LOL. Short trips and extreme heat are pretty much the norm in The Villages. Maybe that is why I am on my third AGM battery in 7 years.

Alternator?
 

I didn't see anyone mention the alternator as a possible failure point. Connect your voltmeter to the battery with the engine running. You should see 14+ volts. Less than that and you have a bad alternator.:gc:

I had a similar problem with my 2008 Acura TL. It wouldn’t start after sitting for two days, but if I charged the battery and disconnected it for two days, then reconnect, it’d crank right up. Sumter Tire in Wildwood diagnosed the parasitic drain for me (related to Bluetooth module) and we decided to just disconnect it.

I certainly appreciate your great response to my issue. I have checked the battery with the multimeter and the numbers are in line with meter manual. I'll be checking this thing out again today in more detail... the alternator and whatever else if I can figure out on the multimeter lol(ok not really lol). Again, thank you

Really?!?????
 

From my experience, few folks slow down or use their brakes here especially in the roundabouts. I wouls think that a trip on Buena Vista from one end to the other would fully charge any battery. :laugh:

Thank you for the response. Several years ago I purchased an "Actron CP7677" for the "just in case scenario". Until now I've never used it. Having to read instructions a couple of times for each mode... takes time, but at least I smile when I get good numbers. I still have a few more test.

Thank you for your help. Oh... the light(s) were the checks I performed. All looked good! Thank you again

Maybe I should hope it's the battery... Probably cheaper than diagnostic testing and then repair!

Thank you for your suggestion.... My intention is to perform that very test sometime today! Thanks!

Oh my... you make me feel "kinda" lucky

I'm just learning about the parasitic drain. My intention is to attempt this testing today. Thanks for your info

If you end up determining that the battery is bad you might want to invest in a battery tender. It's a trickle charger that keeps the battery charged for you when it's parked in the garage. All those short trips keep the battery below a full charge which wears it down faster. IMO your just as well off buying a 36 month battery from Walmart

For any vehicle that sits for long periods, May I suggest a trickle charger battery tender?

Dead battery
 

I've just been down this road with my Porsche, after dealer telling me I needed to replace the battery, some $400 buks and get the car on "Their" computer to set the electronic regulator. Utter B/S, I'm a retired mechanic, so I take to my friend who has a high line repair sho to see about a ghost short. It turns out I was keeping the key too close to the parked car. It would not let the computer and Lord knows what else go to sleep. If the key was in my pocket ,every time I walk past the car it would wake up. Solution, keep the key in bed room till I want to drive it. System has worked now for 4 months. Good luck.

The battery in my Mercedes is under the front seat, so Auto Zone won't check it. To answer your original question I would take it to All German Motorworks in Leesburg off 44. I bring mine there and they are lovely..... Maserati, Bentley, BMW, Porsche, Audi, Mini, Mercedes, Service Repair

Mercedes Battery issue
 

I suggest that you join the Mercedes Enthusiasts Club, to get access to our members only list of recommended vendors: mbenzclub.com

If you put in the battery, you probably did not reset the battery on the car's computer system. Thus, the car has been overcharging the battery since new. A 3.5 year life is great under those conditions. If the computer was reset when newly installed battery, Have the battery tested outside of the car to determine if it is a short in the wiring or a failed battery.

All cars have something that will drain your battery. If you don't drive it frequently get a trickle charger and keep it on that when not in use. So the issue is your battery is dead and will not hold a charge

Check for the obvious first then I would yank the battery or drive it to Advance or other auto place to have it checked. One thing no one asked was have you made any changes to the cars electrical recently like add an accessory or something as simple as a phone charger?

No warranty here. Ran out the later part of April this year. what luck huh?

I would have never thought about that. I do keep my keys close to the car when I'm messing in the garage. Thanks for that "crazy sounding" advice, but I do understand!! I'll surely try to do better!

I do have one for the cart. Good suggestion. Thanks.

If I can't solve this problem using all this help, they very well could be my next choice. Thank you.

My oldie-but-still-goodie car also quickly drains batteries. It seems to need to be started & driven for at least 1/2 hour 1x/week or the battery will be dead. I’ve had it checked & there’s nothing malfunctioning, it’s just a known-hazard from having a lot of electrical features in the car.

As a result, I bought its replacement battery from AAA with my membership. AAA will test & install a new battery curbside 24/7 nationwide & they provide a warranty for the new battery. I checked AAA battery prices & they were actually less than all the others in the area.

AAA membership also includes 3 or 4 curbside nationwide 24/7 services per member per year (depending on the level of membership purchased), including towing to your choice of destination within 100-200 miles, battery jumps, door-lock-out service, gas if needed, curbside new warranted battery installed, and roadside tire change. Family pricing is cheaper for multiple members.

The peace of mind AAA provides is priceless to me. I’ve kept my family on AAA since 1990.

AAA is incredibly FAST too. Once, shortly after my parents died (they died just 26 days apart!) I was so stressed out that I accidentally locked my keys & my little diabetic dog in the car in 100+ degree heat. Of course, we were also in a very rural area of IL at the time. I panicked but I quickly called AAA Roadside Assistance. The AAA response truck arrived in just a few MINUTES! It felt as if he was my Guardian Angel perched on my shoulder! The call center had escalated my call due to a (canine) life-threatening emergency! I’ll never go without AAA! Still makes me tear-up just thinking about it.

AAA also offers a lot of other benefits like member-only pricing for home, auto & life insurance, banking, theme park tickets, dining & entertainment discounts, group travel packages & cruises, and much more. I seldom use everything to be honest but their hotel deals are sometimes very advantageous especially for no-charge late cancellations & AAA has special member services inside Disney World which are awesome. Went on a AAA Disney Cruise with my little girl once & it was super-dee-dooper too.

Kraken Auto Repair call - 352-234-6872

I'm looking for a toy car, a slk550 keeps coming up as a good option, maybe I should pick the brains of your club members?

I did add a dual port USB adapter to the cigarette lighter about 6-8 months ago to use the Garmin. I always unplug the Garmin every time I park. The USB adapter stays installed in the lighter port and always turns off when the ignition is turned off. That's the only thing added.

Thanks for your question.

I did not stay at Holiday Inn Express last night but I have also noticed that my cigarette lighter/USB plug (Anker SmartCharge Spectrum) will drain my car’s battery much quicker. Now I unplug it when I intend to not drive the car for a few days.

VERY COMMON ISSUE IS THE CAR ALARM PULLING A HEAVY PARASITIC DRAW... PULL the alarm Fuse

I find it horrifying with all computers on vehicle’s now the computer can’t set itself from simple battery replacement. At minimum a prompt on screen saying battery reset, o no have to take it mechanics for the extra slicking it you charge. :oops:

Don't leave the electronic key in the "ignition" switch when the car is off and parked in the garage as it will cause a continous drain and could be the problem.

You do not say what model you have. In many cases, MBs of that era have a second, smaller battery located in the rear of the car to share the demand of all the technology. You should go on YouTube and do a search such as “2015 GLK Battery Replacement.” As for a good shop, All German is pretty good. However, next time I need service, I’m going to try Shop 21 in Ocala. Good luck.