labguy

So, my 2008 CLK350 with 80k miles let me down Saturday night. DW and I went out and after stopping to get a gift for a friend, the car would not start and the dash would not light up. Also, the key would not turn.

I called for roadside assistance and the guy tried using his portable battery charger to jump it, but it would not start. We also tried jumping directly with another car's battery. The dash lit up, but it would not even crank. The charger reported that my battery was at 75%.

I have since looked through my maintenance log and I do not see where the battery was ever replaced.

My questions:
Should I assume it is the battery that needs replacing?
Why wouldn't it jump?
Is it possible that this is the original battery? It is OEM.

Thanks everyone!

DRACO

Yeah 75% is a DEAD battery, sorry to type.

Take it to a FLAPS to verify.

labguy

Thanks. Update from Indy Mechanic. The battery has a "short". And will need replacing.

What is a "FLAPS"?

DRACO

Friendly Local Auto Parts Store :-)

Some cars like our MBZ need so many AMPs the alternator is not strong enough on it's own to start or to run the car. The donor car coupled with a dead battery may not have enough amps either. a short does not help too.

labguy

So, after $290 I got my car back and running. I was not happy about the price. And that is after my military discount!

He put in an AC Delco Professional Silver with 30 month warranty. $167 for the battery. $90 for labor to diagnose and replace battery, $20 for "shop supplies" etc...

Ouch!

DRACO

Well, now you are up and running. I'd say invest in a cheap Digital Volt Meter. Next time check the battery yourself. Anything under 12.5 Volts, you need to remove and have it tested for free at a FLAPS.

Shop supplies? Whiskey Tango Foxtrot?

Let's see 10MM socket and Ratchet, Elbow Grease, Used Shop Rag. Disposal fee would have been a more believable charge, even then he get money for the core. Hmm :-/

labguy

Good advice - thanks.

Rudeney

FYI, the reason it wouldn't jump start is because the battery was internally shorted from warped plates. This make it act like a giant resistor. The trick is to disconnect the negative lead from the battery and then try jumping.

floridawriter

Just an FYI, Advance Auto Parts would have diagnosed the shorted battery and installed the new battery for free.

Yidney

Yes, it probably was the original. Mine is still original from '08. I'm torn between replacing it just as a precaution and my curiosity to see how long it will last.

floridawriter

Have the battery load tested. That will tell you if it needs to be replaced.

labguy

That is exactly what I would have done if I had known for sure it was the battery. I didn't want to have the care towed to Adv Auto only for them to tell me it was something other than the battery.

As they say, "hindsight is 20/20".

I think I will get my regular mechanic to load test the battery at every oil change from now on though.

Rudeney

And speaking of Advance Auto, I highly recommend their "platinum" battery - it's an AMG with a full 100% replacement 4-year warranty for about the same price as genuine MBZ. I have one on both cars, and given that the C240 doesn't get driven much, it has proven to be very good at "standing by" for weeks at a time.

pamiboy

So if the price is the same and the warranty is the same, why go to local auto store instead of the dealer?

Fatz

Well for me; The dealer was not going to change it for no labor charge and Adv Auto is a lot closer and they won't take 2-3 hours to do it...... And I've found that if it ain't under warranty, the dealerships treat you as a second class customer......

Rudeney

FYI, my post should have stated "AGM battery", not "AMG"! AGM = Glass Mat.

Anyhow, why buy from Advance Auto? It's a better battery (AGM) and a better warranty: 4 years, vs. 1 year from the dealer.

Long Islander

Interesting. Where I live, Advance Auto warranty on an H8 AGM battery ($135 with coupon) is 3 years and MB battery ($228 with a slight discount) warranty is 2 years.

Long Islander

Wow, 8 years on an original battery? That has to be a record. Our 2008 original battery was replaced under the car's warranty at the 4 year mark (a couple of weeks before the warranty expired).

Rudeney

Yeah, it looks like they have lowered the price but shortened the warranty. When I bought mine, it was $229 (before discounts/coupons) but with a 4-year warranty.