Agreed Larry. Being that the voltage regulator is a voltage comparator that switches on-off, signaling the altenator to charge the battery to an upper limit say, 14.5 volts. At 14.5 v + the regulator is switched off and the battery is allowed to float, it's voltage sinking to a lower limit say, 13.6 v, than switching on again. On-off-on-off...... depending on what the electrical load is at the time, lights or not, the repetition rate will be fast or slow. Adding a capacitor will change the R x C time constant of the circuit, a large C will stretch out the reaction time, slowing the jitter. However, the mane purpose of the electrical system is to start the engine, that requires a large amount of energy for a short time and that translates into lots of amps with very, very little voltage drop, meaning low, low resistance. Now we're talking 0.01 Ohms. Now 6,800uf x 0.01 ohms = 0.00068 seconds. The reaction time of the charging system is much, much longer, maybe one second, than the RC time constant of the cap. Like I said, not much help. See, I had to go off the deep end.
Need Help Adding a Voltmeter
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Soundguy
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we don't care about the meter jiggle at startup.. just during normal operation.
soundguy
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SPYDERLK
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I was speaking of the hi frequency pulses in the rectified AC from the alternator -- a function of rpm, and a source of confusion to a sampling/electronic meter. True, the cap wouldnt be needed with the slowly repeating transients you are bring up.
larry
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Good thinking. I like the analog idea too but am worried about vibration on some tractors. Not usually enuf to be an issue in automotive. Check me on this, but Im pretty sure an analog is going to draw 0.001 to 0.010 A. More than that and the meter would start getting a bit warm. The low end is less than an Amp Hr per month, and were talking 30 or 40AH batteries. By internal leakage the battery self discharges a bunch more than that all by itself -- at least for the 1st few months. The accepted figure is 5% per month.
larry
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crazyal
Super Member
If it was me I would add a hour meter at the same time if your tractor doesn't have one. I would tap into the ignition switch (output side) for power and run a wire directly to the ground on the battery. I would use that same power for any lights the meter(s) have built in if they have their own wires. I think I would just stick with an analog style gauge, they are simple, cheap and usually accurate enough to let you know if things are working as they should.
Will Larry, the only way to know for sure what's going on is to put an O-scope across the battery and alternator output, set up a DVM and test the outcome with various size caps. I still think you'll need a full Farad cap to keep the volt meter steady. And so what if the voltage wiggles some, learn to accept a few thousandths up and down; the moon will not spin out of orbit. As for the meter being a constant drain on the battery, just wire it in on the on-off side of the key switch.
RobertN
Super Member
It's just a voltmeter! Really, we could get in to transients and glitches and trans eschemic events. Even to the sun spot polarization of the flux capacitor. I have stuff at work to measure sub fempto-second timing, and read sub fempto-amp current.
Get a decent quality volt meter, and install by the instructions in the box. Just remember, most are not waterproof, so if you park it outside that might be a problem. Or get a marine/boat rated meter.
Analog gauge is the easiest to read.
One leg goes to ground, one goes to positive.
KISS; keep it simple silly
Get a decent quality volt meter, and install by the instructions in the box. Just remember, most are not waterproof, so if you park it outside that might be a problem. Or get a marine/boat rated meter.
Analog gauge is the easiest to read.
One leg goes to ground, one goes to positive.
KISS; keep it simple silly
RobertN
Super Member
Nah, that is fun stuff. But, it should have it's own thread. Then we could discuss how sun spot radiation affects the electron hole recombination event triggered by an overcharged flux capacitor. Then we can hook up an Agilent 1156B and measure the fempto amp current variation across time and voltage variables.
Even I jumped from Electronics to Emergency Medical Tech; hate those trans ischemic events...
Even I jumped from Electronics to Emergency Medical Tech; hate those trans ischemic events...
OP
Cold Beer
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I'm going to use the stock analog voltmeter gauge from Massey Ferguson, nothing fancy like digital or voice announcing.
It matches the other factory gauges on the tractor for that year model.
I want to add an oil pressure gauge also. I just don't like dummy lights keeping me informed of volts and oil pressure.
The tractor is used about 3 times a week during grass cutting season and not so much in the winter.
Below is the gauge I ordered.
