Adding Inductive Hour Meter To Boat
Printed From: the12volt.com
Forum Name: Marine Electronics
Forum Discription: Boat Stereos, Security, Navigation, Lights, Switches, Gauges, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=114972
Printed Date: May 02, 2025 at 11:49 AM
Topic: Adding Inductive Hour Meter To Boat
Posted By: vwdavid
Subject: Adding Inductive Hour Meter To Boat
Date Posted: July 09, 2009 at 8:34 PM
OK folks, this is my first post and after some browsing thought that this sub forum was most appropriate due to the chatter about ignition coils and tach signals.
I bought a very inexpensive hour meter with the hope of running it on my boat engine which uses ignition coils! This hour meter is meant to wrap around a spark wire and will automatically count engine hours when there is sparking present (ie it also has a little tachometer which I don't really care about).
So, since I don't have spark wires what to do? Well it turns out this inductive hour meter will sense and turn on when connected to any AC voltage- it sees the 3600 Hz pulse and add up run time hours. I was hoping I could just connect it to ignition on DC but of course there is no pulse and it doesn't work.
What can I connect this to on my boat that will give it a pulse when the engine is running? Can I Tap-splice it into an ignition coil wire, or a tach signal wire? Are those signals pulse?
I wonder if I can sense an inductive current from those pulsed wires? Any thoughts?
Thanks
Replies:
Posted By: KPierson
Date Posted: July 09, 2009 at 9:20 PM
I would start by trying to hook it to a fuel injector. If that doesn't work try a coil drive wire. ------------- Kevin Pierson
Posted By: vwdavid
Date Posted: July 09, 2009 at 10:03 PM
Is it generally safe to tap a fuel injector signal wire or would adding a very small drain device cause other problems?
Posted By: KPierson
Date Posted: July 10, 2009 at 5:59 AM
As long as what you are adding is high impedence (low current) you shouldn't have any issues. A fuel injector is a solenoid and the coil of the solenoid is very similar to that of a relay. An extremely small load in addition to the fuel injector won't affect anything. The most important thing is to make sure you make a good connection - you don't want the splice to fail and possibly break the signal going to the fuel injector (ie don't use crimp connectors, ttaps, or scotch locks). ------------- Kevin Pierson
Posted By: vwdavid
Date Posted: July 10, 2009 at 10:24 AM
Thanks, so basically that rules everything out but directly soldering to the wire.
Thanks for the advice. I will update you how it turns out.
Posted By: KPierson
Date Posted: July 10, 2009 at 11:16 AM
:) In my humble opinion, ALL splices should be soldered, but anything that is engine critical or exposed to moisture it is imperative that they are soldered and insulated properly. ------------- Kevin Pierson
Posted By: vwdavid
Date Posted: July 10, 2009 at 1:01 PM
Is it OK to do a scotch lock splice to see if it works, then, make it permanent?
Does a scotch lock (if correct size used) cut the wire? I'd guess not, that if it didn't work I could just take it off and tape it up nice and tight where the insulation was pinched.
Posted By: KPierson
Date Posted: July 10, 2009 at 2:20 PM
A scotchlock, by design, won't cut the wire. However, if you use the wrong sized connector on the wrong size wire it can cut in to the wire.
------------- Kevin Pierson
Posted By: ckeeler
Date Posted: July 10, 2009 at 3:49 PM
the other down side to them is they fall off easily. especially in a situation like a boat. and they allow corrosion into the wire, especially in a situation like a boat. but for a temporary test, it shouldnt hurt as long as the wire doesnt get cut by it.
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