Sluggish starts can also be the starter beginning to fail.

You'd hardly ($167 plus labor, that is) go wrong with changing the battery.

 

Project Farm did an interesting roundup of batteries. Difficult to draw conclusions because the batteries were different sizes, but still it's interesting. Plus I love the guy's autistic yelling at the camera.

 

I had a similar experience except I bought up a car with a “recent battery” but once the temps dropped it was sluggish to start.
Opened it up to test the battery. It was some cheap brand I’d never heard of and lead acid.
I have had a lot of luck abusing Odyssey Batteries off road in my Jeep and truck. I’ve run them dead and still brought them back.
so I got one of the Odyssey performance series and it starts much better now.
testing the old battery tests fine but just isn’t up to the task.

 

All this talk about AGM batteries, but the inside battery in my '10 and '14 ML's were VRLA batteries. I think that was true of my C-Class and GLC . That's Valve Regulated Lead Acid batteries. Which means they are lead acid, but sealed to prevent flammable hydrogen gas and spillage in the passenger compartment.
AGM or gel batteries would also work in interior settings.
I will stick with the VRLA because I think they are more forgiving of abuse. 8 years on the 2010, 6 years on the 2014, and both still going strong when I traded. The C-Class made nine years and then needed replacement.

 

The VRLA is basically an AGM battery. Varta was the OEM for Mercedes and Johnson Controls Inc now Clarios was the OEM maker of the Varta batteries. You can get a Champion from Pepboys which is also Clarios and even Advance Auto and Autozone both have AGM batteries that are also made by Clarios. I would just avoid Bosch which is made by Exide and they're considered worse than JCI/Clarios. They basically sell the batteries by saying they're regular lead acid or AGM.

 

Yes, AGM is a type of VRLA battery.

But I would avoid making General statements about battery manufacturers / distributors and their quality.
Each distributor, whether it be Walmart, AutoZone, or interstate, has the manufacturer build to their certain specifications.
It can be high quality or low quality within the same brand. Even amp hours or cold cranking amps don't tell the whole story.

Probably the most reliable guess how about a batteries service life is it's weight, at least for lead-based batteries. But that won't tell you its suitability for your use.

 

Another lesson learned about Bosch ...

... although Bosch is the world leader in automotive electronics, it’s subsidiary Bosch USA is essentially a marketing organization and hardly any of the products it markets are actually made by Bosch and certainly not in Germany. For batteries in the USA, as noted, the name is just licensed.

Another lesson to be aware of is that actual correct specification Bosch spark plugs for German vehicles are NOT available from aftermarket sources in the USA. What is available are Bosch USA contract made items, which for the most part are resistor plugs even though original specification is not for resistor plugs. If you want the correct Bosch plugs, you’ll need to get them from a Mercedes dealer. Same for owners of some BMW motorcycles (BMW dealer). Just understand that stuff made for USA auto aftermarket is almost by definition cheap stuff. And expecting Pep Boys personnel to know anything about Mercedes is ... just “believe” they don’t and don’t care.

 

It's a big DIY crowd here. I don't even DIY that much, just have an indy do it but I buy the parts. A battery I can still install myself. Pepboys charges to install Mercedes batteries anyway so I wouldn't even bother. Some of the other vendors claim they install for free, but some store managers will decline because they don't want their minimum wage employee to screw it up. You can search for the maker of a particular AGM battery you're looking to install. If it's not AGM it's possible it's made by a different manufacturer. The ones I mentioned I had looked up earlier. Interstate is also basically a distributor so it depends what battery you're buying on the maker of the battery.

 

900 CCA Champion AGM Battery from Pep BOys for $171.(on sale), all in. They wanted $25 to install, which meant moving three clips, unbolting the + & -, and lifting out the 55 pound OEM battery. The biggest issue is to connect a 12V back-up unit to preserve the car's settings. Got almost seven years out of the original battery, which is practically unheard of in Tucson, AZ. My other cars avg. 3-5 years. The heat is a real battery killer, even when garaged when not on the road. This was a 2014 CLS550. Battery fit perfectly, just had to reverse the "drainage" tube. Took about 10 minutes...

 

So where can one lay hands on a Varta brand AGM battery made to MB specs? That’s the one I want because the two I replaced earlier lasted 12 yrs in the Pacific Northwest.

 

You mean aside from the Mercedes dealer which will be top dollar? I don't think any other retailer sells them. But they are basically a rebranded JCI/Clarios battery. The Champion battery at Pepboys is probably the best one at retail. Autozone and Advance Auto also carry the same JCI battery but only have a 3 year warranty unlike the Champion which is 4 years. I think the normal warranty on parts is 2 years at the MB dealer.

 

Back in November 2016, I installed a Bosch Platinum Group 49/H8/L5 AGM. It came with a 4-year warranty. I purchased at Pep Boys - they frequently run specials for 20% off, plus it had another $10 mail-in rebate. Total cost after tax and the ever bogus "core charge" was about $190 here in California.

I also bought a relatively cheap auxiliary battery on-line from Interstate batteries at the same time. 12V 1.3AH AGM - Part #SLA105. Total $22 including shipping.

Both batteries are still going strong after 5 years.

 

If you hear clicking, it is most likely something draining your battery, so it may not be battery's fault. Do you have a volt meter? I went through a tedious task trying to find parasitic draw (i think that is what it is called) in the beginning of the year on the ML as well coincidentally.

 

.

 

It looks like in a year the Interstate battery developed some issue; it sags in voltage even disconnected from the vehicle. There were alternator issues but the battery was never drained completely.

I ordered a Autozone Duralast. I'll try getting a warranty replacement on the Interstate and sell it on Craigslist or maybe keep around as a spare.

 

I'm strongly considering going lithium with Antigravity batteries. Sure, they're significantly more expensive, but should be much more durable as well.

 

The fine folks at Autozone tested the Interstate battery for me. Said it's fine. I asked them if they had a more demanding tester. Sure, in the back. Guy disappeared with the battery, came back, saying, "It's fine."

Really? "Yeah, I tested it three times. Full voltage. But the funny thing is, the capacity drops really fast. It was at 78% by the third test."

I do not know enough about lead-acid batteries to speculate on what is going on inside. Also, I'm guessing capacity = charge level, which does not equal voltage.

The symptom I observed is: Voltage drops rapidly on loading, then gradually recovers. Maybe the glass mat is not fully "absorbed".

 

Well they did to a load test. Maybe it just needs to be fully charged, I wouldn't count on the alternator to give it a full charge especially if you had problems with it.. I'd get a charger, say anything under 10 amps and get it fully charged. Like this one:


That's inflation for you, I got that one for about $25 several years ago. Once it's fully charged, check the voltage with a meter after taking it off the charger for a few hours. That's a battery at rest at about 70 degrees. Should read about 12.7 volts. There's several state of charge charts out there and the lower the voltage the less capacity it has left. Usually a load test is anywhere from 100-500 amps or more. You can get a cheap one too for about $37 (they also used to be $20-$25).

 

I had freshly charged the battery with a (supposed) good tester, the Noco Genius.

I was surprised to see the voltage holding at 12.7V over the next 36 hours. But then I opened the door, which woke up various electronics, and the voltage promptly sagged to 12.3V. I noticed similar when I disconnected the battery to replace the alternator: After reconnection, the voltage was 12.3V. Note that on reconnection there is a sudden drawdown; you have probably smelled ozone when reattaching the cable. So the battery has a funny lack of capacity, like one of the cells became super skinny.

The first test the guy did showed 12.6 / 99%. He was still getting 12.6, or so I think I remember him saying, but the capacity had dropped to 78%. I couldn't tell you what exactly that percent is measuring. The battery is not self discharging, because it climbs back up to 12.6V when sitting idle, like when I schlep it to Autozone.

I might get my own load tester, just for fun. Thanks for the link.

 

I ordered this guy. With the Black Friday pricing, plus another 20% coupon, I paid like $38.

 

Welp. Y'all were right. I guess I did not take into account the effect of temperature on the battery. My fancy pantsy battery tester indicates 93% "capacity".

So now I have a spare battery sitting around. I guess I could suffer worse fates.

 

I hope you never followed through on this. Lithium batteries have a chemistry and profile that simply will not work for starting anything, especially a diesel. Forget that.

 

+1 this comment
Always stick to engaging in due diligence when it comes to vital items, batteries being a prime example...

 

No, but mostly because the economics didn't make sense. Walmart battery was about $150, Antigravity battery is $1000-1400. 7 Walmart batteries will surely last more than 15 years. And also the electrical shenanigans of properly charging and protecting a lithium battery was a deterrent.

As for not being designed for high amperage applications, that entirely depends on the lithium chemistry and construction of the cell in question. For comparison, a Walmart H8 AGM battery has a CCA rating of 850 amps.

LFP batteries, which Antigravity uses, generally don't like to be discharged at rates greater than 1C but certain construction types can handle up to 40C for short periods of time. Based on Antigravity's H8 specs (1800 amps for the 60 AH and 2000 amps for the 80 AH model), they're pushing the LFP batteries at 25-30 C. This will almost undoubtedly cause degradation, especially on long starts, but starter batteries aren't generally used in high cycle count environments so the degradation likely wouldn't be noticed for a long time. Now, if it was used in a vehicle with start/stop tech, the wear will be much greater.

LTO is the other chemistry type that is sometimes used in starter batteries. It can sustain a 10C discharge rate while peaking at 30C without degrading. The downside is that their energy capacity is about half that of LFP- a 30 AH LTO battery would be about the same size as a 60 AH LFP battery.

 

Maybe its somehow different in a Benz. But I've had 3 Interstates for my Land Rover. One lasted 2 years. One was defective on arrival (and replaced under warranty) and the third lasted 2 years. I live a a place that is the 60s -70s year round.