StratTuner
Site Supporter
I have two bare wires connected to battery posts. That becomes a quick connect. Several accessories connect to it, and the volt meter is patched in here.
It starts out at 14.2, and drops as I turn on each accessory.
Anyone running Heated Gear?
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It starts out at 14.2, and drops as I turn on each accessory.
To accurately measure voltage at the battery, the wires connecting the voltmeter, wherever it might be located, must feed only the voltmeter and no other loads. Because several other accessories are also connected to these wires and drawing current, the resistance of the wire causes a voltage drop in the wire (Ohm’s law).
What you are measuring with your voltmeter is indeed the voltage at the end of the accessory wire, but it’s not the actual battery voltage. The voltage drop you see as you turn on each accessory is simply the voltage drop in the accessory wire, not necessarily a reduction in the bike’s charging system.
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drdubb
Site Supporter
I was thinking about tapping in at the headlight. (I think I can get to it without tearing apart the whole motorcycle.)
I want a switched circuit so the voltmeter is not a constant drain. Since the headlight is the only load on that circuit, wouldn't it drop the entire battery voltage?
If I measure at the battery posts, or 6 inches away, as long as there is no load between the voltmeter leads and the battery, I should get batter voltage. The wire resistance should be negligible in that small a run.
If the engine is running, I should be getting the output of the generator at the battery. If the load becomes too great, it will pull down that voltage because the battery and generator are limited in output. In a house hold circuit, the voltage would hold and the current would rise until a breaker pops.
I want a switched circuit so the voltmeter is not a constant drain. Since the headlight is the only load on that circuit, wouldn't it drop the entire battery voltage?
If I measure at the battery posts, or 6 inches away, as long as there is no load between the voltmeter leads and the battery, I should get batter voltage. The wire resistance should be negligible in that small a run.
If the engine is running, I should be getting the output of the generator at the battery. If the load becomes too great, it will pull down that voltage because the battery and generator are limited in output. In a house hold circuit, the voltage would hold and the current would rise until a breaker pops.
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Tapping in at the headlight won’t work perfectly. The two beams, low and high, are wired separately. The two beams are never on at the same time. So if you wire the voltmeter to the low beam, it will turn off when you switch to high beam. Maybe you’re OK with that.
If you’re thinking of wiring the meter to the front running light, be aware that the running lights switch off when the turn signal is activated. Again, maybe you’re OK with the momentary loss of the voltmeter.
If you did decide to go with the headlight connection point, with the bike running, you could measure the voltage at the headlight and compare it to the voltage at the battery. Any difference in voltage would be the voltage drop in the wiring, and would become your correction factor when reading the voltmeter.
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StratTuner
Site Supporter
given that i'm no electrician, i thought about where to connect... what change it might make, but the goal was to have a base line # and then see it decrement as devices started drawing power.
it allows me to see relative draw of each one....and it tells me the device is working....
I never meant to get an accurate reading...wouldn't know one if I saw it.
Laws: I don't know Mr. Ohm much, but I'm well acquainted with his colleague, Mr. Murphy.
it allows me to see relative draw of each one....and it tells me the device is working....
I never meant to get an accurate reading...wouldn't know one if I saw it.
Laws: I don't know Mr. Ohm much, but I'm well acquainted with his colleague, Mr. Murphy.
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