they measure the current. I don't think you notice any real voltage drop on the battery when the fuel level changes... ;-)
You are correct about the reversed polarity. Leslie. -------------------------------------------- On Sat, 4/4/15, Josh Muckley via CnC-List <cnc-list@cnc-list.com> wrote: Subject: Re: Stus-List Problem with 2 new fuel gauges...long story To: w...@wbryant.com, "C&C List" <cnc-list@cnc-list.com> Date: Saturday, April 4, 2015, 6:13 PM All analog meters are just measuring the "voltage drop" across a resistance. The key is to have the appropriate voltage input +12v. If the +12v and the sensing line were reversed then the "voltage drop" would be "negative" driving the needle to the empty peg. Josh On Apr 4, 2015 7:08 PM, "Wally Bryant via CnC-List" <cnc-list@cnc-list.com> wrote: I thought they were Ohm meters. Anyway, I just Googled it to make sure, and see a ton of pages on testing marine fuel sender resistance. Wal you wrote: I agree with your diagnosis. It's gotta be reversed polarity...of the sense and gnd. Fundamentally the fuel gages are just voltage meters. They respond proportionally to the voltage drop across the variable resistance in the sender. I would disconnect the leads and use an ohm meter to measure and validate the resistance of the senders. Switching the polarity of the sense and gnd monetarily probably won't break anything. Before doing so validate that your wiring looks like the attached picture. _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com -----Inline Attachment Follows----- _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com _______________________________________________ Email address: CnC-List@cnc-list.com To change your list preferences, including unsubscribing -- go to the bottom of page at: http://cnc-list.com/mailman/listinfo/cnc-list_cnc-list.com
