Electrical Puzzle

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Jan 21, 2015 | 05:24 PM

FilthyLucre

Thread Starter

Road Master

Joined: Jun 2008

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From: NW Florida

Electrical Puzzle

I was reading another thread about a member trying to figure out where his electrical drain was. It was suggested to put a volt meter between the frame and negative cable to see if there was a draw with the switch off.

I tried it with a digital meter and I got 0.6 volts with the meter set on 20 volts. So I unhooked the regulator and it dropped in half. I then disconnected the starter motor and it dropped some more. With the battery completely disconnected I put the meter on the regulator and to ground and I got 0.24 volts! How is this possible?

I put the meter on my other shovel that didn't even have a battery in it and the regulator showed 0.1 volt. Are the magnets in the alternator enough to create some voltage even with the battery out? The same with the starter motor?

Both bikes have the 82 style alternator and regulator.

I used to just put a bulb in series to see if there was a drain not a meter. The bulb doesn't light.

Jan 21, 2015 | 05:34 PM

Dan89FLSTC

Seasoned HDF Member

Joined: May 2008

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From: South Carolina

When chasing down parasitic battery drain, set the meter for milliamps, not volts.

Jan 21, 2015 | 06:44 PM

Racepres

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Joined: Jul 2014

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From: Cental, MI

Or...Remember the "Starter Run-On" thread???
Nuther good reason for a Cut-Off switch.

Jan 21, 2015 | 09:59 PM

SeaZund

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Joined: Mar 2010

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From: D/FW Texas

the regulator will have some internal filter capacitors that will retain some voltage after the bike has been run, then turned off. When you put your meter in there to look for voltage, the meter itself will be drawing a very small amount of current out of those filter caps. I would bet that if you left the meter in circuit and came back a day or 2 later, the meter would have drained those regulator filter caps, and you'd then read 0 volts. A momentary probe with the meter would show you the voltage, but wouldn't draw much current, because as soon as you saw the reading, you then removed the meter leads.

A test light tester requires more current to light up it's light bulb...much more current than the filter caps could provide. The voltage was still there (as the meter proved) but there just wasn't enough "umph" (as in current...milliamps) to energize the test light bulb.

Last edited by SeaZund; Jan 21, 2015 at 10:08 PM.

Jan 22, 2015 | 08:19 AM

Racepres

Seasoned HDF Member

Joined: Jul 2014

Posts: 8,590

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From: Cental, MI

^^ Very Eloquently put, and Accurate ...
I have Never, Ever, even thought about it..A good battery and a Proper charging system and Go....Hell! I don't even use a "Tender" either.

Jan 22, 2015 | 12:13 PM

FilthyLucre

Thread Starter

Road Master

Joined: Jun 2008

Posts: 1,078

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From: NW Florida

It's amazing that the regulator will hold voltage for that long. Electricity has always been a mystery to me.

I retested with the meter set for DCA first at 10A then 200 m. Zero on both. there are other setting on my meter that escape me. There is a 200μ and 2000μ what are they for?