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06-22-2018, 12:45 PM | #1 |
Senior Member
Join Date: Oct 2012
Location: Malvern, PA
Posts: 361
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Strange behavior...
My car's not mine.
I have a 1929 Roadster, totally stock, always reliable and nice running. A couple days ago I noticed a slight discharge reading on the amp meter on shut down, maybe an amp or so. The next morning the battery was dead, no lights, no horn, nothing. So today I jumped it off another A and ran it at high enough rpm to get a 10 amp charge back to the battery while I played with things to find where the draw was. Turned out the horn button was the culprit eliciting a variable discharge on the amp meter as I wiggled the button but didn't sound the horn. Pain in the neck but fairly straight forward, and I've seen this before. Now here's the strange thing, I pulled out my voltmeter set to 20v to just do some checks and when I set the positive lead to ground without even touching the negative lead, the meter went nuts, readout constantly and rapidly changing. Checked my modern car battery, and got a steady 12v. Back to the Model A and this time didn't even need to touch a lead to anything before the meter went nuts. Almost like some wierd RF field was in the vicinity. Don't recall that ever happening before. Ghosts in the machine?
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Wayne @ Barb Malvern '19 T Speedster '26 T Touring '29 A Roadster '30 AA Stakebed '30 A Pickup '30 A Town Sedan '31 A Station Wagon '38 Columbia Girls bike (WWII) '40 Elgin Boys bike (WWII) '42 Super Deluxe Tudor '42 Willys MB Jeep '43 Willys MBT Trailer '43 M3A4 Hand Cart '43 Harley Davidson 42WLA with sidecar |
06-22-2018, 01:00 PM | #2 |
Senior Member
Join Date: Apr 2013
Location: Northwest CT
Posts: 1,092
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Re: Strange behavior...
Engine was running when you were testing things with the meter? If it was, the ignition system throws off tons of RF interference. Is it a digital or analog meter?
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06-23-2018, 02:13 PM | #3 |
Senior Member
Join Date: Oct 2012
Location: Malvern, PA
Posts: 361
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Re: Strange behavior...
Yep, engine was running and it is a digital meter. Guess I'd actually never tried running circuits with the engine running before.
__________________
Wayne @ Barb Malvern '19 T Speedster '26 T Touring '29 A Roadster '30 AA Stakebed '30 A Pickup '30 A Town Sedan '31 A Station Wagon '38 Columbia Girls bike (WWII) '40 Elgin Boys bike (WWII) '42 Super Deluxe Tudor '42 Willys MB Jeep '43 Willys MBT Trailer '43 M3A4 Hand Cart '43 Harley Davidson 42WLA with sidecar |
06-23-2018, 03:08 PM | #4 |
Senior Member
Join Date: May 2010
Location: Largo Florida
Posts: 7,225
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Re: Strange behavior...
A digital meter will do that sometimes. Good catch on the horn circuit. You've got yourself quite a stable, nice.
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06-23-2018, 03:32 PM | #5 |
Senior Member
Join Date: May 2010
Location: Between Seattle & Tacoma
Posts: 2,351
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Re: Strange behavior...
I actually blew up an infrared temp gun doing that. Bought a new one and as I brought it into the engine compartment, it started going nuts, and that’s when I realized what was happening.
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06-24-2018, 03:44 PM | #6 |
Senior Member
Join Date: Oct 2012
Location: Malvern, PA
Posts: 361
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Re: Strange behavior...
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Wayne @ Barb Malvern '19 T Speedster '26 T Touring '29 A Roadster '30 AA Stakebed '30 A Pickup '30 A Town Sedan '31 A Station Wagon '38 Columbia Girls bike (WWII) '40 Elgin Boys bike (WWII) '42 Super Deluxe Tudor '42 Willys MB Jeep '43 Willys MBT Trailer '43 M3A4 Hand Cart '43 Harley Davidson 42WLA with sidecar |
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