John CC

A few days back, it was -15F here (-26C). I've always been concerned that mine cranks slowly, but it has always started, usually after 2 or maybe 3 compression strokes, and the battery has always tested good, until the other day...

It cranked very slowly, maybe estimated 60 RPM (about 2 compression strokes per second.) It did not start, but it also did not grind to a halt. I quit trying because I didn't want to kill the battery in case I had to leave it for a few days. AAA came and put a jump box on it and it started instantly.

So, I guess my question is, what is normal cranking speed? Is there a speed below which it will not deliver fuel? I suspect I need a new battery, but I'm wondering if maybe the starter could be weak, too.

Yesterday I put the battery on a battery maintainer. Within about 3 hours it indicated full charge. I then tested it with a cheap (Harbor Freight) resistance tester and it indicated 800 CCA.

Today the plan is to pull the battery and take it to a parts store to have it tested with a capacitance tester. I just don't want to spend $200+ on a new battery only to find out in 12 months that it was not the problem...

Plutoe

do you know if your car came with a block heater---if so use it!

John CC

If it did, I can't find it, or any information on it. First (of many) Diesel I've had that didn't have one.

kajtek1

Observe the car voltage during cranking.
It could be battery getting weak, or might be starter with some burned coils.
Cranking the engine with low voltage can fry some electronic modules.
Dealer's mechanic fried ignition module on my Sprinter this way. $1000 added to the bill.

John CC

Did some checking. There is no coolant pre-heater installed.

John CC

Update: I had the battery tested with a capacitance tester and it checked good for 800 CCA, but needed to be charged. I think that's because I had it tested after the third of 3 very short (less than one mile) trips. My system voltage is over 14 volts, so, unless there's something keeping the system voltage from charging the battery, that's not the problem.

(The day I had the no start it had been driven 50+ miles 3 days before, then parked. It was about -15F the night before and around +10F when I tried to start it.)

Tomorrow morning it's supposed to be about -5. We'll see if it starts without a jump. Day after it's supposed to be about -15 again. I'm packing jumper cables this time...

I have a volt meter plugged into the cigarette lighter socket. It isn't fast enough to catch the cranking voltage if the engine starts. If it fails, I'll try to get a reading in the next couple of days. Charging voltage is over 14 volts.

Etienne Lau

How old/how many miles on the battery? Anything past 4-5 years, the battery is on borrowed time.

John CC

I've only had the car since June, so I don't know. There's a possibility it was replaced when the car was traded in, so it would be less than a year. It looks new and has a sticker from MB-USA. The car was not generally serviced by the dealer when the previous owner had it, so a MB battery would probably not have been the replacement. If I remove it it may have a date sticker on it, but I'm not going to do that now. Regardless, it has been tested twice and tests at about 800 CCA.

Etienne Lau

It's a 2014. No way visually looking at it to know whether that's the original factory battery or you have a near new battery. You CCA 800 reading is a good sign.

How many miles on the engine itself? My thoughts it maybe a weak starter or a weak battery. I also have a 2014 ML 350 Bluetec, with 102,000 miles. I am the 2nd owner, and as far as I know, it's still on factory starter, but 2nd battery. I just replaced the battery in 2018. The only symptom I had the battery was bad, was I went out one day to start it and nothing(click). I connected a battery jump pack and it started right up.

John CC

The car has about 76,000 miles. Since the battery says USA on it I'm assuming it is not the original one. It was not dead and didn't even indicate it was dying. It was still cranking at the same speed when I gave up. I'm going to call the dealer that took it in trade to see if I can figure out what they serviced.

John CC

The cheap Chinese cigarette lighter volt meter shows about 10.1 volts while cranking. Problem is, by the time it shows a drop, the engine has already started. If it fails to start I'll get a better read on it.

I think the meter itself is about 0.4 volts low. It read lower than expected on my previous car, too. Problem is I don't have anything to calibrate it against.

John CC

OK, -15F this AM. I had the battery maintainer on the car all night. Green lite/fully charged indication when I took it off. Cigarette lighter volt meter showed about 12.0 volts. (Not fully charged...) I got a different volt meter and put it directly on the battery terminals. pretty much the same reading. So, I tried to start it. It started in the usual 3 compression strokes. But, the voltmeter dipped to 7.5 volts while cranking. I was dumbfounded! System voltage immediately rose to about 14.8 volts on both volt meters.

Then I got frostbite trying to put the cabin air filter back in place.

So, everything except the professional battery tester indicates I need a new battery. And, it's too bloody cold right now to try to change it.

[edit] Guess I'm gonna have to freeze my fingers off. I rechecked the car fax and the battery was replaced by a dealer almost 4 years ago to the day.

Etienne Lau

@John CC Yup looks like you need a new battery. 4 years is the almost end of it's life. If it was rated 800 CCA new, it's probably down in the 400-500 CCA at this point. Might even be below 300-400 CCA with the cold weather.

Mawk1

This little tool is invaluable for MB battery swaps:

https://www.performancechiptuning.co...lighter-cable/

It plugs into your OBD2 port and has a long enough cord to reach an adjacent car's lighter socket to draw enough power to keep your memory settings for the radio, clock, seats, windows, sunroof, ABS etc. etc. from being lost when you disconnect your battery. Real time and patience saver! Works on any car, but MBs are especially susceptible to memory losses, despite having an auxiliary battery on many models. Go figure...

GoodByeHonda

When forced with having to replace the battery, what do you guys recommend? If anyone looked into this issue, kindly share your findings.

kajtek1

The batteries quality went down in last years, so your only choice is to calculate warranty v/s price.
For years I've been finding PepBoys having the best deals. They had Bosch flooded batteries for $100, but discontinued the brand, so now the choice for MB is Champion AGM for about $220.
In some areas Costco might carry the size and they usually have the best deals, but I could not find the size I need in Las Vegas. Still for my boat bought battery at Costco for $69

John CC

[soapbox]
50 years ago a good lead acid flooded call battery could go 10, 12, even 14 years before you had to replace it. 40 years ago you could get a flooded cell lead acid battery for less than $1.00 per month of (pro-rated) warranty. 30 years ago you could get a maintenance free, flooded cell lead acid battery for about $1.00 per month of (pro-rated) warranty. 20 years ago you could get a maintenance free, flooded cell lead acid battery for about $1.00 per month of (pro-rated) warranty, and there was a good chance it wouldn't last the warranty period. Today a sealed, flooded cell lead acid battery is well north of $100 and comes (if you're lucky) a 36 month warranty. Chances are you'll take advantage of the warranty; I have several times. A similar AGM battery costs north of $200 and doesn't come with a better warranty.

So, why no 10 year batteries any more? Could be one of several thing. First, they just don't make them like that any more. And, they don't. Cost cutting, lighter weight, more power in the same size box, all compromise longevity. The plates are thinner and closer together, for one thing. Also, today's cars are much more demanding on the electrical system. Gone are the days of going to the drive-in for a double feature. (gone are most of the drive-ins, too... )
[/soapbox]

John CC

Well, after much consideration, I ended up ordering an Odyssey battery from FCP Euro. It's (IMHO) a superior battery to the likes of NAPA or AutoZone's offerings. The price was $250 plus $10 for oversize (weight) shipping. Odyssey has a 3 year warranty but FCP covers it for lifetime, so, as long as I pay shipping, it'll last for the life of my ownership. It should arrive today, but it's -15F right now, and I'm sure the car won't start, and I'm not about to sit out there fussing with tools today, so it'll have to wait until tomorrow.

kajtek1

Come back in 3 years and tell how the Odyssey work for you?
Champion batteries can come with 4 years warranty, when FCP runs modified Ponzi scheme and I can only wonder how long they will last.
I lucked on my last Bosch battery, who drop the performance a month before warranty would expire. Since PepBoys discontinue the brand, I've got new Champion with much higher MSRP.
One of the issues with modern car is much more electronics draining the battery. Especially when you have smart charging, who every couple of minutes discharge the battery and than charge it with high current. Batteries don't like it.
For me close to 40 mpg in city driving and quieter car at red lights is worth replacing the battery every 3-4 years, but some members have different opinions.
For comparison, our friend drove Lexus SUV on her 3 miles commute. She averaged 5 mpg in warm months.
Her husband is smart man and now she drives GLK Bluetec.

John CC

I wouldn't have no luck at all...

I went to change the battery today. Yesterday was sub-zero and tomorrow is supposed to be a blizzard, so today seemed like the best choice.

Got the old battery out, no problem but no easy task with the strut for the hood in the way. Dropped the new battery in place (no easy task with the strut for the hood in the way). (Note to self: look into how to get the hood vertical.) The battery didn't sit right, so I hauled it back out (no easy task with the strut for the hood in the way). Found one of those little plastic rivets from the top of the heater box on the battery tray. Set it aside for later. Dropped the new battery in place, again (no easy task with the strut for the hood in the way). The front bolt for the hold down clamp wouldn't thread in. Hauled it back out, again (no easy task with the strut for the hood in the way). Decided the only way to fix it right was to remove the battery tray. Only three bolts holding it in place. They all have loctite on them, one is completely hidden behind some sort of duct that is not obviously easy to remove, and all are hard to turn due to the hood strut in the way...

Got the battery tray out and found the captive nut cross threaded, likely by the dealer mechanic that installed the battery 4 years ago. Cleaned up the hole with a tap. Couldn't find my tube of blue loctite. Off to the parts store for another one. Now I have at least 3, somewhere... Put the battery tray back in place. Dropped the hidden bolt under the tray. Go get the magnetic retrieval tool and coax it out of hiding. Put retrieval tool on the engine cover and watched it slide off and fall down the side of the engine past the DPF and stop on a heat shield, unreachable from above or below. If only I had a second magnetic retrieval tool... I'll deal with it later...

Got the battery tray back in place, battery in the tray (no easy task with the strut for the hood in the way) and the battery cables back on. The red plastic cover for the positive terminal won't fit because the bolt for the terminal sticks up to high. Remove negative, remove positive, and discover the bolt cannot be easily removed. I was going to swap it with the one on the negative terminal, which is shorter. Replace positive, down as far as it will go. Still about 1/4" to high, but I hope it will be good enough... Put the cabin vent box back in place. Scrape 1/4" of skin off my arm retrieving the magnetic retrieval tool.

Fired it up and immediately noticed something different. The voltage went to 14 point something then dropped to about 12. Smart charging? I had never noticed that before. Maybe it was because my old battery was never completely charged. This engine always starts easily, unless it's -15F, in which case it turns over OK but doesn't start, so I really didn't notice much difference other than the charging behavior. Went off to do errands and everything performed as expected.

Oh, (apologies to Colombo) just one more thing... On the way home I remembered the plastic rivet for the heater box. Figured it was gone forever. When I got home I popped the hood, and there it was, right where I left it, on the plastic shelf behind the headlight. So, at least one thing went right... for the most part...

Etienne Lau

@John CC Hood moves to vertical position by you pushing to the vertical position. Nothing special needed.

John CC

Now you tell me....

It didn't look like the struts would extend any further.

On my W126 there were some releases you had to push. Never tried it on the GLS.

B34chBum

Glad you've got past the issue (at least for now).

A couple of things you might consider for future, and contending with cold snaps:[indent=40px]- https://www.costco.com/type-s-8000mah-power-bank-jump-starter-with-lcd-screen.product.100813421.html[/indent]

John CC

There is a red button on one of the struts (Driver's or left on my car) that you have to press to allow it to go into the vertical position, and again to bring it back to the normal position. Other than that. easy-peasy. Wish I had known that the other day!

GoodByeHonda

mercedes stamps date of battery production on negative battery terminal