MarylandGLK250B

If it ain't broke, as they say.....

Nevertheless, I thought I would ask about battery life. My GLK entered into service on 12/23/13, which means I've had it almost 7.5 years now. Odometer reads 95K miles. It's still got the original battery, which has never needed a boost.

Should I replace it prophylactically at the next service (likely in August or so, 100K miles)? Am I playing Russian roulette with the current battery?

Mmr1

An old battery gets weak, the voltage and reserve continues to drop. My 13 with 60000 was tripping a power amp to fail when I’d start it, I’d have to pull and replace the fuse all the time. An old battery can damage your cars computers from low voltage. It’s a risk at that age and miles to even think of keeping it. At least take it for a free test at most any auto parts store. But from my experience at that age I’d say get a new AGM battery.

Silver Shadow

I'd say keep on going with your original battery. You'll get warnings that it's starting to weaken. You're in SC so it doesn't get very cold in winter but that is when symptoms would start to show up.
Government mandated reductions in lead content mean that new batteries do not last as long as the old ones did. "They don't make them like they used to" is true in this case.
As suggested, getting it tested wouldn't be a bad idea.

Mmr1

I can’t find any info on gov mandated reduced lead content. I don’t believe it.

formerjeepguy

The battery is 7-8 years old now so it is end of life. You can replace it now and control the circumstances or you can wait for failures and have the circumstance control your actions.

About a year ago my 2015 was starting and running fine, but the eco start/stop function would take longer and longer to function after starting the car. Eventually the eco button would not even light up, but still no alerts on the dash. This February I decided to proactively replace the battery and I immediately noticed a faster cranking speed and the eco function operated normally immediately without having to wait for the battery to charge.

I chose a NAPA premium AGM because they are a nationwide chain and in my experience their parts/service are better than the other chains, and I didn't want to pay the dealer premium for a commodity item.

Leetom

Replace both main battery and Aux now. My 2013 ML made it 9.5 years then just wouldnt start one day. No warning lights beforehand. Luckily I was anticipating it, so I was prepared. Pretty straight forward replacements using some youtube videos. I stayed OEM because of the length first one lasted, and the main battery was only $20 more than aftermarket, and Aux was like $5 more. Save about $300 in labor and do it yourself. Remember, AGM battery for main, NOT lead acid.

John CC

Here's the battery history for my GLK:
Build date 2/27/2014
First registered end of March 2014.
Battery replaced end of January, 2018 with an MB battery, made in Germany.
Failed to start at -15 F middle of January, 2022.
Battery replaced end of January, 2022

So, pretty close to exactly 4 years each.

ecohen2

Your batteries have lasted way beyond their expected life. Preventive maintenance.. Replace them....

bugelrex

FYI: for those who want to DIY. I followed this youtube video. It really was that easy... except you will need 2 ppl to help lift out/in the battery because it's in the corner
OEM battery from dealer was $260. Needed a 10" 3/8 extension rod to reach the bolts. Note to remove the negative first and be careful not to short

dealer wanted $500 for the replacement, even a local indy wanted $400. its crazy

John CC

Seriously? I'm almost 72, a couch potato for the most part, and I did it by my self, and that was before I figured out how to get the hood vertical!

I paid $260 for an Odyssey battery from FCP Euro. Hopefully it'll last more than 4 years, but even if it doesn't, they offer a lifetime warranty. Don't know if I'll be able to lift it 4 years from now, though...

bugelrex

wish i knew about the hood vertical. You must be very tall, I seriously struggled on this and decade younger than you

John CC

Nope. 5'8". Healthier than I deserve, though.

Yeah, red button on the driver's side strut. Press it to release the stop and push the hood straight up. Press the button again to lower it to the normal position. Reaching around the hood strut with the battery was a huge PITA.

Here's my whole battery saga, if you've got time on your hands.

bugelrex

curious if you have done the AUX battery for GLK250, this will probably go out soon too. It does not look DIY friendly.

mogulman

I agree, about replacing both. On my 2013, I replaced my main first, but was having draining issues. I replaced the rear and all is well now. It's pretty inexpensive and easy to do it yourself.

John CC

I understand that's only for the cars with eco start-stop, right? Mine is very bare bones. Nothing like that.

bugelrex

There is a owner with GLK250 in the US who replaced theirs: The steps listed seem a little tricky as they had to remove some interior panels (i think).

Not sure if I should wait for failure or do it before.

2015 glk250 bluetec auxiliary battery location | Mercedes-Benz Forum (benzworld.org)

sams_6

Though counterintuitive, if your battery is located under the hood with the engine, it is more likely to fail in HOT weather than cold. Most manufacturers make batteries specifically formulated for warm climates (liquid batteries anyway - not sure about AGM). A benefit of having a battery in the trunk or under a seat is that it does not have to withstand the hot engine compartment, especially in warm climates.

No sense pushing a battery too far past it's specified lifespan. In my experience, AGM batteries are not as long-lived as liquid batteries, so if you have a "60-month" AGM battery I wouldn't push it too far beyond that, especially if you drive a lot of miles. You'll end up needing a battery when you are far from home and cannot shop for a specific battery or a good price. If you are a DIYer, buy the battery of your choice for $200 and install it yourself instead of getting stuck and having to pay Meineke for a house-brand battery and installation or, even worse, have an MB dealer replace the battery for $400+.