Long crank time after sitting for a few minutes & another tank issue
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Joined: Oct 2010
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Your new clamp can be set to capture the IN-RUSH peak value !!
The peak would equate to the instant current before the engine decides to spin.
I'd guess 6 to 750Amps peak ✌️
This peak current is the truly destructive spike with all electric motors. The way around it is an electronic "slow-start" that ramps up current from zero, instead of down from high Infinite.
The peak would equate to the instant current before the engine decides to spin.
I'd guess 6 to 750Amps peak ✌️
This peak current is the truly destructive spike with all electric motors. The way around it is an electronic "slow-start" that ramps up current from zero, instead of down from high Infinite.
Obviously I'm not electrician so I did not even know about this inrush thing. I just bought a meter big enough to handle the Amps. I will test again and capture the inrush current.
When I had the issue with the E550 and changed the starter I test run the old starter using AWG 12 wire. It burned that wire just running the starter by itself. I did not test the new starter but I doubt it takes that much current, but I don't know.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Your new clamp can be set to capture the IN-RUSH peak value !!
The peak would equate to the instant current before the engine decides to spin.
I'd guess 6 to 750Amps peak ✌️
This peak current is the truly destructive spike with all electric motors. The way around it is an electronic "slow-start" that ramps up current from zero, instead of down from high Infinite.
The peak would equate to the instant current before the engine decides to spin.
I'd guess 6 to 750Amps peak ✌️
This peak current is the truly destructive spike with all electric motors. The way around it is an electronic "slow-start" that ramps up current from zero, instead of down from high Infinite.
My meter does not go to inrush mode other than in AC. Not available in DC.
The manual does not say anything about not having that in DC so is my meter defective?
Anyway, took new measurements today on both E550 and S550. I used the MAX mode on the meter so I guess this is the max current the meter saw.
This is the 2010 E550
This is the 2013 S550
Little surprised the E550 starting current is that much higher but this is what the meter shows. The car had been sitting for 11 days before this start.
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From: 122W, 37N
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
my engineering friend calls those DC clamp-on meters 'amp guessers'. they aren't terribly accurate except under ideal conditions
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Joined: Oct 2010
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
And today the S550 took about 20 A more current than yesterday as the engine was cold, I suppose?
Last edited by Arrie; May 19, 2021 at 04:02 PM.
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From: 122W, 37N
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
200-300 amps momentarily is not unusual for a starter motor. 12 volts at 200 amps is about 2400 watts, which is a bit over 3 horsepower.
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From: San Jose, CA
11 E550, 16 AMG GTS, 13 S550
Slow hot starts are a known starter issue. My 997 and E550 both had the exact same symptoms which a starter replaced. I went with a TYC unit off Rockauto for both and they both had reduced gear ratios and spin the motors up quick. It's like a two hour job to the uninitiated. The exhaust on the right has to be removed.
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Joined: Oct 2010
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Slow hot starts are a known starter issue. My 997 and E550 both had the exact same symptoms which a starter replaced. I went with a TYC unit off Rockauto for both and they both had reduced gear ratios and spin the motors up quick. It's like a two hour job to the uninitiated. The exhaust on the right has to be removed.
I bought a starter from AutoZone but I'm sure you cab buy one from other car part stores too. I use AutoZone because they are located just 2 miles from my house and I have not had any part fail from them yet other that brake pads wore out twice on my E550 that I got free replacement for too.
My starter replacement did not require any removal of any exhaust parts at all even when the new starter was slightly longer than the original one.
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From: San Jose, CA
11 E550, 16 AMG GTS, 13 S550
Had reduced gear ratio? It had "gear box" between the electric motor part and the small pinion gear wheel that spins the flywheel of the engine? I don't think so. There simply is no room for that.
I bought a starter from AutoZone but I'm sure you cab buy one from other car part stores too. I use AutoZone because they are located just 2 miles from my house and I have not had any part fail from them yet other that brake pads wore out twice on my E550 that I got free replacement for too.
My starter replacement did not require any removal of any exhaust parts at all even when the new starter was slightly longer than the original one.
I bought a starter from AutoZone but I'm sure you cab buy one from other car part stores too. I use AutoZone because they are located just 2 miles from my house and I have not had any part fail from them yet other that brake pads wore out twice on my E550 that I got free replacement for too.
My starter replacement did not require any removal of any exhaust parts at all even when the new starter was slightly longer than the original one.
Yeah you can weasel it out without the exhaust but mine was hot and in the way and I like the luxury of space and visibility
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
This sounds very weird. If the gear wheel is smaller it would spin the engine slower with the same starter speed. Also, the starter would need to be made with offset mounting location as if the gear wheel is smaller then the starter shaft must be moved closer to the flywheel to get the smaller and less teeth having gear to mesh correctly with the flywheel gear.
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From: 122W, 37N
2016 E350 4Matic wagon, 2019 Ford Expedition, 2019 Chevy Bolt EV
I've seen geared starters that fit engines with a conventional starter, they use a higher RPM motor which tends to be smaller and more efficient at a given power level, and a gear mechanism which, yes, is offset from the motors output shaft, so its certainly doable. my son used one on his Vanagon Westy camper, that had a "Tiico" conversion using an Audi inline 4 adapted to the VW transaxle.
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
So, for the OP to troubleshoot further he needs to get one of these meters and measure the MAX current at every start until he experiences a long crank. Then he could perhaps see higher than normal current and that would directly point to the condition of the starter.
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2006 slk350 n
Update
Ok I charged the battery from on one of my tenders from another car, ran the car a short while and unplugged the “sensor” on the negative cable. The car sat a few days. No additional charging, Went to go to the grocery store and it cranked fine drove approx 25 minutes (15 of that highway). Watched the voltage in the display and it hovered between 12.8 to 13.8 Got to my first store shut it down went into the store for 15 min, when I went to start it it BARELY CRANKED super slow at first and also had the long crank, but it started, Went to second store a mile down the road 2 minutes and got brave since there is a parts store across the road shut it down and went shopping for another 20 min. Guess what... it cranked strong and for the normal period!!! WTF?? Went to a third store another mile down the road and it also cranked and started normally after I shopped as well... If anything it got basically no charging in between stores and should have been worse. Does this tell us anything?? It was mid 80’s and dry if that matters. Lol now our Smart car is making a crazy noise I think in the A/C system.... guess I’m getting some of the German car quirks I have always heard about.
What the heck could cause it to crank the worst after a good long drive, and crank normal after a short battery depleting drive right after....
What the heck could cause it to crank the worst after a good long drive, and crank normal after a short battery depleting drive right after....
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,141
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
Ok I charged the battery from on one of my tenders from another car, ran the car a short while and unplugged the “sensor” on the negative cable. The car sat a few days. No additional charging, Went to go to the grocery store and it cranked fine drove approx 25 minutes (15 of that highway). Watched the voltage in the display and it hovered between 12.8 to 13.8 Got to my first store shut it down went into the store for 15 min, when I went to start it it BARELY CRANKED super slow at first and also had the long crank, but it started, Went to second store a mile down the road 2 minutes and got brave since there is a parts store across the road shut it down and went shopping for another 20 min. Guess what... it cranked strong and for the normal period!!! WTF?? Went to a third store another mile down the road and it also cranked and started normally after I shopped as well... If anything it got basically no charging in between stores and should have been worse. Does this tell us anything?? It was mid 80’s and dry if that matters. Lol now our Smart car is making a crazy noise I think in the A/C system.... guess I’m getting some of the German car quirks I have always heard about.
What the heck could cause it to crank the worst after a good long drive, and crank normal after a short battery depleting drive right after....
What the heck could cause it to crank the worst after a good long drive, and crank normal after a short battery depleting drive right after....
