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.

Access to this page has been denied

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.