low charge voltage at startup - Page 3 - PeachParts Mercedes-Benz Forum

LoosBenz · #31 11-30-2010, 05:48 PM

Quote:

Originally Posted by tangofox007

Just like every other alternator in existence.

OK...glad we cleared that up

Quote:

Originally Posted by tangofox007

If the field excitation circuit is not intact, no amount of revving is going to move any electrons.

Many alternators are self-energized by the residual magnetism in the rotor when revved above "X" amount. The Jeep I used to have would start charging at above 2500 RPMs (3-wire type alt with missing exciter wire).
If this is the case with his car, the OP can go out and rev it up right now and find out if this is the case with his without any effort. Easy check. If it doesn't work, oh well.

Quote:

Originally Posted by tangofox007

You don't agree with the "afterglow" theory?

I didn't say I didn't agree. I just offered an alternative that would take all of about two minutes to try.

thayer · #32 11-30-2010, 07:23 PM

Quote:

Originally Posted by funola

12 V on a battery after 2 days is not good. A 0.13 amp draw should not bring it down that low in 2 days! Alternator not charging properly? Belts loose? Bad battery? Get a cig.. lighter voltmeter from Radio Shack and watch it while you drive and report the results. You should see 13 to 14 v depending on the electrical loads.

So I fired her up with the volt meter in the cig lighter. while it was glowing I got 11 volts. Fired her up...down to 8.....she's running....11.2...11.4...11....11.5. Driving for 30 secs..still around 11.5....little less than a mile in the city and an entire minute later...now we are at 14.1....turn the headlights on...13.8 to 14 depending on revs.

The belts are great, the alt is charging after a minute. This is what my initial post was about...why does it take a whole mile to get the charge up. My buddy's 86 sdl goes to 14 almost instantly.

My guess as it stands right now is the battery. If it is on its last leg, could it be sucking the alt dry in order to get back up to voltage initially?

bustedbenz · #33 11-30-2010, 07:29 PM

Check the voltage regulator just to rule it out as a possibility. Maybe making intermittent contact and just making you think it has to do with driving that mile. Stuck brush had to have a mile's worth of road bumps to make contact and start charging again?

funola · #34 11-30-2010, 07:54 PM

When the key is in the on position, is the battery light lit? If not, replace the bulb! It provides excitation to the alternator.

Maybe you have contact problems. Take the voltage regulator out and check brush length. If the brushes are on the short side, pull on it to stretch the spring. Better yet, replace it! If the brushes are good, use brake clean and a tooth brush and clean the gunk that is all over the regulator and reinstall. Also remove the connector on the alternator and scrape clean the terminals with a small flat bladed screw driver.

To check the battery, put a charger on it till fully charged and bring it to Autozone/ Advance for a load test.

JHZR2 · #35 11-30-2010, 07:55 PM

Hearing that it sounds like the alt isn't getting sufficiently excited to produce share until after it recovers from the gp cycle...

thayer · #36 12-01-2010, 06:42 AM

Quote:

Originally Posted by funola

When the key is in the on position, is the battery light lit? If not, replace the bulb! It provides excitation to the alternator.

Maybe you have contact problems. Take the voltage regulator out and check brush length. If the brushes are on the short side, pull on it to stretch the spring. Better yet, replace it! If the brushes are good, use brake clean and a tooth brush and clean the gunk that is all over the regulator and reinstall. Also remove the connector on the alternator and scrape clean the terminals with a small flat bladed screw driver.

To check the battery, put a charger on it till fully charged and bring it to Autozone/ Advance for a load test.

battery light always lights up when I am glowing...then it goes away when its running...then it blinks as I turn off the car.

I checked the regulator...the brushes are worn in the direction the alt spins but they still have a great deal of of length left on them. I'll clean the terminals.

I'm also going to be on the lookout for a higher amp alternator at the junk yard. this whole 65amp game is for the birds. With a battery the size of my tool box and enough torque to make mid size trucks jealous...I'm just saying.

vstech · #37 12-01-2010, 08:46 AM

Quote:

Originally Posted by thayer

So.....if I lose two glow plugs will my indicator light still light up?

it depends on which plugs fail... but the answer is maybe.

I'd love to be one of the TWUTGPR members... but it's best to just notice it's on or not in the morning, and listen for the relay to click when it's cold. if it does not come on, check your glow plugs.

Thayer...
have you tried starting it while measuring the voltage, and then unplugging the glow plug harness from the relay and checking if the voltage INSTANTLY jumps to 14?

tangofox007 · #38 12-01-2010, 09:24 AM

Quote:

Originally Posted by vstech

it depends on which plugs fail... but the answer is maybe.

Why would it matter which two plugs failed?

hey_allen · #39 12-01-2010, 10:01 AM

Quote:

Originally Posted by tangofox007

Why would it matter which two plugs failed?

Because the glow plug light being on is controlled in part by a circuit that compares the current draw on a few of the glow plug pins in the relay.
Certain combinations can still light the lamp, while others won't.

If I remember what I read a while back, cylinder 1 is compared to the rest, but I don't know the actual ins and outs beyond that.

tangofox007 · #40 12-01-2010, 10:17 AM

Quote:

Originally Posted by hey_allen

Because the glow plug light being on is controlled in part by a circuit that compares the current draw on a few of the glow plug pins in the relay.
Certain combinations can still light the lamp, while others won't.

Absent a malfunction in the fault detection circuit, any combination of failures involving two plugs will generate a fault indication.

funola · #41 12-01-2010, 11:05 AM

Quote:

Originally Posted by tangofox007

Absent a malfunction in the fault detection circuit, any combination of failures involving two plugs will generate a fault indication.

I can test that for you since I have installed quick discconnects on my glow plugs (got rid of the 8 mm nuts). I can disconnect and connect any combinations of glow plugs in seconds.

funola · #42 12-01-2010, 11:17 AM

Quote:

Originally Posted by thayer

battery light always lights up when I am glowing...then it goes away when its running...then it blinks as I turn off the car.

I checked the regulator...the brushes are worn in the direction the alt spins but they still have a great deal of of length left on them. I'll clean the terminals.

I'm also going to be on the lookout for a higher amp alternator at the junk yard. this whole 65amp game is for the birds. With a battery the size of my tool box and enough torque to make mid size trucks jealous...I'm just saying.

I had a voltage regulator where it was charging between 13 to 16.5 V. Brush length was fine but it was very gunky and dirty, covered in black crud. I scraped most of it away and used a wire brush to clean it as best I can, especially around the soldered joints and component terminals where shorts can have negative effects on voltage regulation. After doing that , it charges normal at 14 v. I was concerned with the high voltage since I just put in $40 worth of H3 head light bulbs and didn't want to burn them out.

vstech · #43 12-01-2010, 11:30 AM

Quote:

Originally Posted by hey_allen

Because the glow plug light being on is controlled in part by a circuit that compares the current draw on a few of the glow plug pins in the relay.
Certain combinations can still light the lamp, while others won't.

If I remember what I read a while back, cylinder 1 is compared to the rest, but I don't know the actual ins and outs beyond that.

in the parallel circuit, at the relay, I think all 5/6 terminals are connected together. I don't think the relay can distinguish between 1 or the other4/5 I certainly do not have ANY working knowledge of the relay, just what I have read here on the forum for the last 8 years, and my experience with the failures me and my customers have encountered.
currently, all 5 of my plugs are heating up, and the car is starting smoothly, but the indicator light is not lighting up. it could be a bulb, it could be a fault with the relay. I'll swap a few relays in and out and see if it makes any difference. I will also pull the cluster and inspect the bulb/swap if it's bad.

thayer · #44 12-22-2010, 07:46 PM

Revitalization anyone? SO....the saga continues

Advance just handed me a new battery, Gold someotherwhatsit - 950 cranking amps....500 cold cranking amps.....12.98 volts....that was nice to see.

So, I finally did the test that VStech told me to do like two weeks ago.

I plugged my voltmeter into the battery - 12.98 volts
Set it on the windshield and started the car.
Dropped to 12.38 volts with a warm engine idling.

Pushed on the linkage - 12.7 volts at about 2000 rpm

Pulled the glow plug relay plug ....14 volts

Plugged it back in - 12.3 volts...no...12.28 volts

pulled on the linkage...got it up to around 13 volts at about 3k rpm.

Watched it for about a minute...12.38..then BAM! 14 volts at idle (13.8 to 14.1)

So apparently I do have "afterglow".

Somebody talk to me about .13 amps being too much key off amp draw. What should I be shooting for off amp draw wise "assuming that 0 would be the best, but then I wouldn't know what time it is as I only know how to read analog clocks"

thayer · #45 12-24-2010, 11:14 PM

found the .13 off amp draw. it was the power antenna. after I unplugged the antenna I got 0 readable off amp draw. no remote entry, no bass amp, and no power antenna....its like driving a ford taurus.