Need a little help with electrical

I am having a couple electrical issues.
1) I am getting a high voltage to my guages
2) My tach stopped working

I have a couple of questions. Could grounding 2 batteries to the same post on the engine block cause problems?

Is the grey wire in the photo the tach wire and if it is will it read 0 amps if the sensor is bad?

Which wires do I test from the alternator/regulator to troubleshoot the high voltage issue? The photo is not great, but it shows how the regulator is mounted externally to the alternator.

Any help would be appreciated.

Troy, I just got done helping my friend solve a high voltage issue which popped the breaker on his 92 Sport Naut. His only has a single battery, and I tested the voltage across the terminals of the battery with the engine off (no alternator), and with the engine on. You should see in the neighborhood of 12.5-13.5 volts with no alternator running and about 14-15.5 with the alternator running. You may want to check your gauge up front too by connecting you meter to the two inputs on the back of the gauge, just for accuracey. You may get slightly higher readings than those ranges +/- half a volt. If your alternator reading is higher than 15.5 you may have a problem, and could fry your battery.

We still suspect that the regulator went, the voltage went over the gauge limit (16++) when we had problems. We replaced the alternator with built in regulator on the back of the alternator. The boat has run nicely thus far, about 3 hours of run time.

The ground on the 92 Sport Naut is all on one post on the block. Everything in the boat is grounded there. My gut feeling is that gounding a second battery there should do no harm as it is the block tha grounds everything anyway. If you are putting another battery in, I would definately get one of those isolators and see what the manual says about grounding the second battery.

If that thick wire is the grey one, it looks more like your selinoid (sp?) for the starter, or the starter itself. It will only draw when the boat is starting, and may take alot of amps when doing so. That blue-grey thick wire with the rubber cap looks way too big to be a gauge wire.

We had a post going called "Breaker keeps tripping, what's wrong?" There is some good info there. Boat electrical is frustrating, but with some patience and a multimeter you can learn alot and hoopefully you just have a faulty regulator and can replace the alt/reg and get back to the water.

What kind of boat/engine??

Troy:

"1) I am getting a high voltage to my guages"

How did you measure this,and what is the voltage? Which guages are you seeing this voltage on?

"Could grounding 2 batteries to the same post on the engine block cause problems?"

Grounding both batteries to the engine block is the preferred method. The only issue with putting two wires to the same post is making sure that you can get the bolt tight. Losing the ground connection can cause all sorts of hard to diagnose problems.

"Is the grey wire in the photo the tach wire"

I am not sure what I am looking at in that photo. Is the wire you are referring to the big one on top? This sort of looks like the ignition coil, and that big wire would be the main spark wire heading off towards the distributor, so NO, that is not the tach wire.

If that is the coil then the tach wire would be one of the smaller wires in that connector bundle.


"and if it is will it read 0 amps if the sensor is bad?"

You have lost me here. I would not expect you to be measuring amps in a situation like this.

Generally, the tachometer connects to the "-" side of the coil. On the old fashion "points" ignition system this would also be the place where the points connected. New electronic ignition systems can have all sorts of different arrangements however.

The Tachs that I am familiar with don't have a "sensor", just a wire running from the coil to the Tach guage on the dash. You could check the validity of this wire by using a voltmeter or test light at the tach: when the points are open, you should get +12 volts on this wire. When the points close, the voltage should go to zero. If you connect the voltmeter, turn the ignition on, then slowly turn the engine over you should see the voltage swings. To turn the engine over, I would put big socket on the main pulley. I highly recommend pulling the main spark wire out of the center of the distributor so there is no way the engine could fire while you are cranking on it with a wrench!

If you have an old fashion "needle" type volt meter you can read the voltage while the engine is running. I would expect it to read a few volts. I would expect a digital meter to just go nuts.

"Which wires do I test from the alternator/regulator to troubleshoot the high voltage issue?"

How high is the voltage???

A fully charged battery with little or no load should have about 12.5 volts on it. If the battery is discharged a bit the voltage could be a little lower, perhaps down to 12.2 volts. A voltage below that is either a really discharged battery or it has a heavy load on it.

Once the engine starts and the alternator is working you should see at least 13 volts. This is about the minimum voltage I would expect to see if the alternator is actually charging the battery. At a higher RPM, the alternator should put out more and the voltage should increase to at least 13.5 volts. If the battery was really discharged (i.e., your batter was dead and you were just jump started) it may take a few minutes before the voltage comes up.

As the battery gets charged up, the voltage should come up and current out of the alternator go down. At 14 volts, your battery should be close to being fully charged.

I would not be surprised to see as much as 14.5 volts. If it gets any higher than that, you have a problem.

Tim, Rod

Thanks for the long answers. I will be testing the alternator/regulator tommorow using tim's reccomendation. Several people in other threads have stated that it is not unusual for a aternator/regulator to let out up to 15.5 amps. If this is true, I will need to put a limiter in line with my guages.

Rod, I am still confused about my tach wire. I have a digital speed control that says my tach wire is either broken or disconnected and my analog guage is dead. I cannot trace this wire without undoing about 10 bundles of wires at the distributuion panel. I have tried to use a digital meter at the guage with the engine on (assuming it had to be on to get a reading) as I made contact with the positive needle (ground needle not yet grounded ) I got a spark and the engine temporarily lost power. I did not go any further.

The point of my post was to try and identify the tach wire so I could run a test wire from the command module to the coil. If this worked then I would tear apart the harness and put in a new wire. If you look at the picture again, I am referring to the grey wire next to the larger purple wire (They are almost touching about an inch from the plug)

I will also look more closely at the coil to see if it is plugged into the side.

Thanks

Troy

Troy, are you not confusing Amps and Volts???
Those two are two main different things.

a aternator/regulator to let out up to 15.5 amps

It's normal that a alternator put out a 14,5/15,5VOLTS. How many AMPS differs of how many you batery needs it..

Cheers Tommy

Tommy,

I did mistakenly refer to the 15.5 amps. My problem is that my digital guages can not handle over 15 volts. If it is normal for the alt to put out up to 15.5 volts. I guess the solution is to put a voltage reducer in line with the sensative guages.

Thanks for clearing that up. Now I will check the amp output at the battery and the volt output at the guages to see if there are any abnormal readings.

Troy:

you should never see anything above 14.5 volts. While the alternator is capable of generating any voltage it wants to, the voltage regulator should be keeping it to a suitable range.

If the voltage gets over 14.5 volts all sorts of damage could result. Light bulbs won't last very long. Blowers and pumps can overheat. Stereos and other electronics can be ruined. Even the battery will suffer, as that high a voltage will cause excessive gassing and the battery will lose water like crazy.

Troy,

Rod is right. Check you're regulator. Perhaps 1 or 2 bridges of you're AC/DC converter is broken. A new regulator is not that expensive and mostly easy to install. An normal system will put out 14-14,5V. 15,5V is to high! You can put a voltage reducer between the lines, but I prefer to solve the problem at the roots.

Good luck!