voltmeter wiring question

[BrendellaJet]

I have my voltmeter wired to the "on" terminal on my ignition. The gauge registers 12 volts and does not change as RPM's increase. Should I be wired to the "batt"terminal instead?

[Big Inch]

I would think that your on terminal would give a constant 12 volt reading unless volts dropped under that. What type of boat? If there is a relay feeding the ignition switch it won't be accurate is my guess but I'm no expert.

[BrendellaJet]

I would think that your on terminal would give a constant 12 volt reading unless volts dropped under that. What type of boat? If there is a relay feeding the ignition switch it won't be accurate is my guess but I'm no expert.
Thats exactly whats happening. No relays. This is actually 2 different boats I wired with the same result.
Boat one(jetboat): 3 wire delco alternator. did the one wire jumper to convert it to a poor mans 1 wire. Charging wire goes to the battery cable on the starter. Volt meter wired to the "on" terminal on the starter.
Boat 2. (v-drive): Real 1 wire delco, charge wire to the batt terminal on the starter. Volt meter wired to the "on" terminal on the starter.
Both boats register 12 volts when key is on. Seems like if I swap to the Batt terminal I will get a reading of the charging voltage which should increase with rpms...

[Big Inch]

I'd comment but I'm probably wrong and I don't want to steer you in the wrong direction or add confusion. I'm sure someone more edumacated will chime in soon.

[BrendellaJet]

go ahead and reply, boards are slow.

[SmokinLowriderSS]

Unless you want the voltmeter to read CONSTANTLY (and be a small drain on the battery) it belongs on the "run" side of the ignition switch, in some manner (ie, spliced into any other circuit on the "run" circuit, or directly to the terminal, makes no difference).
The voltage SHOULD CHANGE from engine off to engine running, arround 1.5 to 2vdc, not more.
Running is generally 13.3vdc or higher.
Anything above 14.5 is high, and is also bad. It WILL cook the battery.
Off should be somewhere above 12.4 depending on the condition of the wiring coming foreward to the switch. Too small, or old/bad connections causes a voltage drop.
Check both sides of the ignition switch with a good voltmeter. If there is more than a tiny voltage difference, the contacts in the switch are getting bad, and the switch should be replaced. It happens eventually.
Then, check with the voltmeter that the alternator actually puts out when the engine is running. A zero voltage increase means the alternator is bad, or miss-wired, or bad wiring/connection somewhere.

[BrendellaJet]

Unless you want the voltmeter to read CONSTANTLY (and be a small drain on the battery) it belongs on the "run" side of the ignition switch, in some manner (ie, spliced into any other circuit on the "run" circuit, or directly to the terminal, makes no difference).
The voltage SHOULD CHANGE from engine off to engine running, arround 1.5 to 2vdc, not more.
Running is generally 13.3vdc or higher.
Anything above 14.5 is high, and is also bad. It WILL cook the battery.
Off should be somewhere above 12.4 depending on the condition of the wiring coming foreward to the switch. Too small, or old/bad connections causes a voltage drop.
Check both sides of the ignition switch with a good voltmeter. If there is more than a tiny voltage difference, the contacts in the switch are getting bad, and the switch should be replaced. It happens eventually.
Then, check with the voltmeter that the alternator actually puts out when the engine is running. A zero voltage increase means the alternator is bad, or miss-wired, or bad wiring/connection somewhere.
Both switches are new.
all wiring is new. All connections are tight and both alternators tested good. One gauge is a new auto meter, the other is a known good VDO. SO, that leaves how the gauges are wired. You say to the run position, can you equate that to Batt, On, or Start, as those are how the terminals are labeled. Currently the gauges are wired to the "on" terminal on the switch.
Is it wrong to expect the gauge to read higher while at higher RPM's? If not maybe they are set up correctly. I will check the voltage change from off to running and see if that helps identify a problem.

[RICHARD TILL]

3 wire delco alternator; run a wire from the no.2 terminal to the big post on the alt. going to the battery. Then you should see an increase in voltage up to charging rate as you increase r.p.m`s.

[BrendellaJet]

3 wire delco alternator; run a wire from the no.2 terminal to the big post on the alt. going to the battery. Then you should see an increase in voltage up to charging rate as you increase r.p.m`s.
That part is set up right. question is what terminal on the key switch shouldthe volt meter be wired to.

[Oldsquirt]

The "ON" terminal is the correct one to connect the voltmeter to. This way, meter will only read with the key "ON". If connected to the "BATT" terminal the voltmeter will read all the time which will cause a small key-off draw on the battery.
Honestly sounds like a "no charge" situation. Either a connection mistake or alternator that isn't functioning. Hard to believe that both would suffer the same failure....
Go back and perform the voltage tests using a handheld test meter. Measure with key off at the battery and then at the alt output. Voltage should be within a tenth, or so, at both points. Repeat with engine running.
Don't forget that the alternators need a good ground to function properly.

[BrendellaJet]

The "ON" terminal is the correct one to connect the voltmeter to. This way, meter will only read with the key "ON". If connected to the "BATT" terminal the voltmeter will read all the time which will cause a small key-off draw on the battery.
Honestly sounds like a "no charge" situation. Either a connection mistake or alternator that isn't functioning. Hard to believe that both would suffer the same failure....
Go back and perform the voltage tests using a handheld test meter. Measure with key off at the battery and then at the alt output. Voltage should be within a tenth, or so, at both points. Repeat with engine running.
You have "blipped" the throttle to get those one wire alternators charging, right?
Oldsquirt,
thanks for responding. No blip of the throttle, but have raised RPM to 3k rpm and saw no difference that I recall. I will test.
Charge wire off of alternator is running to the starter. Should we run to the battery instead?

[Oldsquirt]

Charge wire off of alternator is running to the starter. Should we run to the battery instead?
If the output wire is connected to the same terminal of starter as the B+ cable, you should be good. No need to run all the way to the battery.
Perform the voltage checks suggested and double check that alt has good ground.

[BrendellaJet]

where should the alt ground to? perhaps this is the problem...? Is the alt bracket attached to the motor sufficient, I dont recall seeing a terminal for this...

[Oldsquirt]

Generally, the alternator just grounds through its mount. If I remember, you have a front mount alternator setup. Perhaps with all the paint on the block it isn't getting a good ground.
Is the v-drive your dad's and does it use a similar alternator mount?
You can measure the voltage drop directly. With one lead of voltmeter connected to the battery negative terminal and the other to the alternator case, run the engine. You want the LOWEST possible reading, like .1-.3 volts. A HIGH reading indicates a poor ground circuit between alternator and battery.
If necessry, you can run a separate ground from the alternator to the engine block.

[SmokinLowriderSS]

There should not really be any appreciable voltage increase above aprox. 1,500 to 2,000 RPM. The charging voltage should remain quite stable (within 1/2 volt or so), but MAY drop off at idle.
That behavior may alter some if you have a very small dia. pulley on the crank to reduce alt. RPM and parasitic HP loss.
My 1-wire requires arround 1500 to 1800 to trigger it, but then it charges very evenly, as do all the ones in road vehicles I have.
The lack of voltage increase at all indicates a problem somewhere.

[v-drive]

I just pulled out my vintage issue of "Hotline news". I used this article when I did the one wire alternator on my old Studebaker.
alternator to to the battery terminal on the starter. gauge goes to fused terminal on run or accessory position. That's what the book says and it worked perfectly on the stude...v-drive(aka)pop

[BrendellaJet]

oldsquirt, the vdrive was my dads. It now belongs to my sister. It is mounted to the V drive bracketry, only connected to the motor via the driveline, perhaps I should run a ground from the alt. housing to the block??
Gonna check the volts with the motor off and then when motor is on. Will do this tomorrow.

[Rexone]

Keep in mind that when grounding an alternator, Paint, Powder Coat, AND Anodize are all insulators and will not transfer current. Oil on bolt threads too. I normally run a ground wire to the block from the alt case if there's any doubt on the good ground. As said above you should be seeing above 12V running normally above 13, and around 12.4 at rest again as posted above. 12V even, all the time means something isn't correct.

[BrendellaJet]

Thanks guys. Grounded the alternator and its all good now.