Electical puzzle

After running a 10 gauge wire and not getting any difference on the gauge I kinda figured I wouldnt worry to much about the gauge and just make sure the alternator/voltage regulator are working well. Just for the heck of it I will run a parallel 8 guage ground. At that point I feel like I've done everythig possible.

Once again, I appreciate all the help!

John...You've got the right idea

Tim

    Tim, you are getting about 1/2 volt drop across the ground feed to the dash fron the engine block, then paralelling another wire to it should drop it down. You will need at least a #8 wire to cut the voltage drop about a little more than half of what you have now. When you add the parallel wire, check the measurement with voltmeter again, and it should go from .48 (existing) to something lower when you hook on the parallel wire. Honestly, if thats all your running for accessories, I wouldnt get to nervous about it. I would fix the alternator so she does at least 13.8 volts. As far as the volmeter goes, its really not accurate where it is wired in. This is true with most voltmeters I have seen. If you really want to get fancy, you would have to run a seperate fused run (hot and ground) from the battery cables where they go on the engine to feed the voltmeter directly, eliminating the dash wiring to it. You would also have to put a small relay (very common at any auto parts store) at the voltmeter, tied into the ign switch so the voltmeter doesnt run 24/7 and drain your battery.
    As far as the alternator goes (and being marine) I have always had mine rebuilt at our local alternator/starter repair shop. You can check the diodes with a digital voltmeter using the diode check. Should get anywhere from .5 to .8 volts drop in the forward direction and nothing in reverse.
    My recommendation is to either buy new, or remove the regulator and alt and bring it in to a shop. It cost me about 90 bucks 3 yrs ago to fix. This also included new bearings which are just as important.
    Good luck as always!!
                                  Jeff....

Looks like I need to run another ground wire and replace the diode trio in the alternator. I'm heading out of town tomorrow so it will be next weekend before I can work on it. I'l llet youknow the results. Thanks again all.

Hey, just out of curiosity, how do you test if the voltage regulator is bad or the ealternator itself. I have an external voltage regulator, if that matters.

Tim

New numbers

With blower, nav lights and bilge on, RPM at 1000


A = 0.43
B = 0.18
C = 13.15
D= 12.49

While I was hooked up for "D" I switched one lead to the engine block ground (meassuring across main positive at dash to main engine ground) and got 12.9 Seems consistent with the reading in "A".

Also while this was going on the voltage across the battery terminals was 13.1

Hope I got it right this time.

Tim

    It seems as though the measurements in A,B,C,D dont make sense. Its like the measurements were taken wwith no loads. You should be loosing way more than .04 volts unless you have welding cable feeding the dash. Maybe I confused you on the steps because the other info you gave makes perfect sense. 13.0 volts from dash + terminal to ground makes sense, then lowers as you turn on accessories. What did you use for a ground on that measurement?? Was it at the dash also?? The object of the game to find where you are loosing voltage by measuring the voltage from one end of a wire to the other.
    For example, you are loosing .15 volts across the ign. push button with accessories on. So if you were to then ground the meter on the engine block and measure the FEED to the ign push button, and lets say it reads 13.2 volts. If you then move the meter to the other terminal(OUTPUT), then you should read 13.05 volts. This is because you are loosing .15 volts through that switch. Notice 13.2 volts minus 13.05 volts equals .15 volts that you measured across it.
    It also sounds like all the accessories run with the ign pushswitch since you get more voltage drop across the switch when more are turned on.
    Need to recheck the steps ABCD and see whats goin on. Step D should be your low 12.5 volt range like the voltmeter in the boat. Hope this all helps and doesnt confuse you too much!! You certainly are thourough (sp?) in your testing. That is cool!
    Good luck!!                 Jeff...

pps,

oops, should have said there was NO change between 600 and 1000 rpm

Glad you're there Jeff. This stuff makes my head spin.

I think I found the main positive and ground wires comming in. They feed into a plug which then splits out and supplies the gauges, lights etc. However, I couldnt find a place to make the readings so I stuck a pin in each wire for the recordings. Hope that doesnt affect accuracy. Heres the data you requested.

A) 0.02
B) 0.04
C) 13.47
D) 13.45

What does this tell you? My guess isI'm losing a little on the positive side and have a decent main ground. Is that correct?
If so I suppose the main problem is "downstream" in the gauge wiring itself?

Here is some other info in case it's helpful


At 600 RPMs.....
Voltage from alternator "+"cable to engine block =13.52
Voltage across battery = 13.46
Dash voltage gauge reading = 12.6
Voltage across dash voltage gauge terminals = 12.9
Voltage from dash "+" terminal to ground = 13.00
same asabove with blower on = 12.72
same as above with blower and lights = 12.5
same as above with blower, lights and bilge pump = 12.35
same as above with lights only = 12.65
same as above with bilge pumponly =12.69


At the push button igniton circut breaker (not key ignition)
when running,"+" to actual ground = 13.42

Across push button "ignition" terminals = 0.06
with blower 0.09
blower and lights = 0.14
blower lights and bilge = 0.15


ENGINE SHUT OFF
across battery = 12.95


So whats the diagnosis doc?

Tim

    Thanks Jear! Someday we will talk again about 66 blocks! White, Orange, Green, Brown, Slate.

Martinique87, sorry for the short hi-jack of the post.

    You are definately getting a serious voltage drop in one of the main lines to the dash. A very easy wat to tell which line it is(hot or ground) thats feeding the dash is by doing this. Engine running at fast idle with the blower and lights on.

A) Take a digital voltmeter and measure between the ground wire at the dash and the engine block and record the voltage. Note: on all readings dont worry about the polarity of the meter leads, just take the voltage reading number.

B) Take the voltmeter and go between the dash hot main feed wire and the positive battery terminal at the engine and record the voltage.

C) Take the voltmeter and go between the engine ground and the batt positive wire at the engine like in step B and record the voltage.

D) Take the voltmeter and measure the voltage at the dash from the main ground wire to the main hot wire and record the voltage.

Now take the results and look at them. Steps A and B are measuring how much voltage you are loosing in that particular wire. If you take the voltage from step D and add the losses from steps A and B to it, you should end up with the voltage reading of step C.

Hope this helps! This is a FOR SURE way to tell where the major problems are without GUESSWORK!! Good Luck!!
                             Jeff...

Now for the dash gauges. While I was talking with Woody I asked him about that. He recommended two things. First, he recommended re-grounding all of the gauges. He asked me if the temp gauges changes when I hit the blower...sure enough it does, by about 5 degrees. Apparently that's a classic sign of a grounding problem. Second he recommended cleaning all connections between the battery and the gauges (e.g., the wiring harnes plug by the driver's side vlave cover).

I did the second one and while there was plenty of green gunk, it did'nt change anything on the dash.

Running a new ground looks like a big project since each gauges is wired in series with the one next to it. But I may have to do it.

Thanks surroundsound for the help. Glad to know I'm okay as long as the battery is getting 13.5 volts.

Tim

In order for a 12v batt to charge, it has to have more than 12v put to it. Typically they are around 14. Your voltmeter would be the correct reading.
As long as when the engine is running the meter on your dash isn't showing a negative charge your in good shape.
I hope this makes sense. I could draw a better picture than I can explain it. Basically, when the alternator is being used, anything that is wired in parallel with it that is less voltage than it is (the battery) is a load, therfore it puts puts voltage into it. Although that's not really the correct term. Voltage is a measure if the difference in and out. You probably get what I mean.

It is normal for the volatage on the dash to drop when there is more of a load.

There has to be something somewhere wired wrong, most likely in or out of the solenoid. This happened on me once in my 86 Ford. I got a new solenoid b/c the old one was shot, but I got the wrong part.

I would initially think that the magnetic flux is keep the solenoid shut, but Jeff makes a good point too. It could be the high current.

Not sure if any of that helped or not. hehe. But you shouldn't have to worry about the dash.

    The only possible way for the starter to run continuously, is by the solenoid either being stuck or energized(due to a backfeed or ign wiring problem). Disconnect the batt cable at the starter, and use a test light at the cable that feeds the starter to get it to fail and troubleshoot. Disconnecting the starter cable and using the test light will prevent you from destroying the flywheel or starter until you find it.
    If the test light always goes out when you release the key, then it maybe the solenoid contacts welding themselves together with the high current draw of the starter.
    Good luck!!
                                   Jeff..