Cruisers Forum
 


Join CruisersForum Today

Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 03-06-2017, 12:16   #1
Registered User

Join Date: Apr 2015
Posts: 1
Adding engine total hour "Hobbs" meter / How?

I'd like to connect an engine 'total running time' meter, often called a 'Hobbs' meter. Wondering how to wire it such that the meter gets +12 VDC only when the engine is running (or, perhaps more specifically, when the Alternator is producing DC). Since the Balmar 60 series alternator DC output is connected directly to the batteries, that won't work (as the meter would turn continuously). The Balmar has a 'Diode Trio Output' that (apparently) goes low (to ground) when there is an alternator failure - seemingly meant for a "dash light" indication of trouble, so this seems like a dead-end. Any ideas on how / where to connect would be appreciated!
__________________

sophieoreo is offline   Reply With Quote
Old 03-06-2017, 12:25   #2
Moderator
 
a64pilot's Avatar

Cruisers Forum Supporter

Join Date: Oct 2013
Location: Albany Ga.
Boat: Island Packet 38
Posts: 23,601
Re: Adding engine total hour "Hobbs" meter / How?

Usually a Hobbs is wired through an oil pressure switch, no oil pressure, engine won't run long.
__________________

a64pilot is offline   Reply With Quote
Old 03-06-2017, 12:48   #3
Registered User

Join Date: Jan 2017
Posts: 10,024
Re: Adding engine total hour "Hobbs" meter / How?

There are little battery-powered units that just wrap a sensor wire round the top of a spark plug.

The better ones are resettable, store maintenance interval checkpoints.
john61ct is offline   Reply With Quote
Old 03-06-2017, 13:48   #4
Registered User

Join Date: Nov 2015
Location: Fl
Boat: Wauquiez Hood 38
Posts: 1,163
Re: Adding engine total hour "Hobbs" meter / How?

This might help . . .Click image for larger version

Name:	HourMeterSchematic.jpg
Views:	716
Size:	41.2 KB
ID:	149116
__________________
Keth

Boat Vinyl Lettering and Graphics
Bleemus is offline   Reply With Quote
Old 03-06-2017, 16:26   #5
Certifiable Refitter/Senior Wannbe
 
Wotname's Avatar

Cruisers Forum Supporter

Join Date: Jan 2008
Location: South of 43 S, Australia
Boat: C.L.O.D.
Posts: 8,903
Re: Adding engine total hour "Hobbs" meter / How?

Quote:
Originally Posted by a64pilot View Post
Usually a Hobbs is wired through an oil pressure switch, no oil pressure, engine won't run long.
To expand on this; not just any oil pressure switch. Some have only one terminal with will usually be "normally closed" which means the are contacts open when oil pressure is present. Two terminal switches may be "normally closed" or both. Three terminal switches are always both.

The OP needs a "normally open" set of contacts i.e. the contacts close when oil pressure is present.

Of course a relay can be used if the existing switch is "normally closed". The relay can invert the switch logic.
__________________
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
Wotname is offline   Reply With Quote
Old 03-06-2017, 16:41   #6
Registered User

Join Date: Dec 2016
Posts: 705
Re: Adding engine total hour "Hobbs" meter / How?

FWIW, I've been through three of the ISSPRO electronic hour meters. They don't seem able to last through a winter in the cockpit. Third one mounted inside the companionway, OK so far.

Suggests a faulty learning curve - should have switched to a mechanical dial unit by the time the third unit came along...

Hey, that means my engine still only has 16 hours! Great resale value!
toddster8 is offline   Reply With Quote
Old 04-06-2017, 08:58   #7
Registered User

Join Date: Oct 2014
Location: Panama City Beach, FL
Boat: Beneteau 343
Posts: 245
Re: Adding engine total hour "Hobbs" meter / How?

Sorry for the deviation but I thought I'd toss out an idea that worked for me; my Yanmar hour meter has performed poorly but seems to have correct hours when it chooses to show them. A couple years ago I installed a cheap vibration meter and it seems to work well. I log hours for most every trip so if it fails I won't lose track of anything.
EmeraldCoastSailor is offline   Reply With Quote
Old 04-06-2017, 13:32   #8
Registered User

Join Date: Jun 2010
Location: Des Moines and the Lesser Antilles
Boat: PDQ 44i
Posts: 186
Re: Adding engine total hour "Hobbs" meter / How?

Our Yanmar meters both worked well for a couple of years then intermittently for a while, then occasionally, and finally not at all. I kept track of engine hours in the log until I found some meters, and then installed Seachoice engine hour meters, about $40 each, as follows: checked all the pins on the back of the ignition switch panel until I found one that showed 12V only when the ignition was in the "on" position, then wired the meter to that pin. It works fine.
doublewide is offline   Reply With Quote
Old 04-06-2017, 17:26   #9
Moderator
 
roverhi's Avatar

Join Date: Aug 2005
Location: Kona, Hawaii, Carlsbad, CA
Boat: 1969 Pearson 35 #108 & 1976 Sabre 28
Posts: 6,592
Send a message via Yahoo to roverhi
Re: Adding engine total hour "Hobbs" meter / How?

Bought a cheap hour meter on eBay. Wired it to the switched hot side of the ignition. Works great and no messing the oil pressure sender.
__________________
Peter O.
'Ae'a, Pearson 35
'Ms American Pie', Sabre 28 Mark II
roverhi is offline   Reply With Quote
Old 04-06-2017, 23:25   #10
Registered User
 
Nineteen's Avatar

Join Date: Apr 2015
Posts: 85
Re: Adding engine total hour "Hobbs" meter / How?

Quote:
Originally Posted by a64pilot View Post
Usually a Hobbs is wired through an oil pressure switch, no oil pressure, engine won't run long.
+1 all light aircraft and plant are done this way👍
Nineteen is offline   Reply With Quote
Old 05-06-2017, 08:48   #11
Registered User

Join Date: Apr 2017
Location: Winnsboro, Texas
Boat: Catalina 30 MKII
Posts: 262
Re: Adding engine total hour "Hobbs" meter / How?

Quote:
Originally Posted by Nineteen View Post
+1 all light aircraft and plant are done this way👍
Agreed, sometimes an ignition switch can be turned/left on while the engine isn't running and can mess with the actual record of running time.
ValiantV is offline   Reply With Quote
Old 05-06-2017, 09:04   #12
Registered User

Join Date: Feb 2013
Location: Lago de Izabal, Guatemala
Boat: Seafarer36c
Posts: 4,925
Re: Adding engine total hour "Hobbs" meter / How?

Quote:
Originally Posted by ValiantV View Post
Agreed, sometimes an ignition switch can be turned/left on while the engine isn't running and can mess with the actual record of running time.
Airplane maker Cessna was so clueless for years. On some models the fuse for the Hobbs was under the glove box. You could pull the fuse while you were flying. Hours are billed from the hobbs, not the tach.
Ecos is offline   Reply With Quote
Old 05-06-2017, 23:46   #13
Registered User
 
Nineteen's Avatar

Join Date: Apr 2015
Posts: 85
Re: Adding engine total hour "Hobbs" meter / How?

Quote:
Originally Posted by Guy View Post
Airplane maker Cessna was so clueless for years. On some models the fuse for the Hobbs was under the glove box. You could pull the fuse while you were flying. Hours are billed from the hobbs, not the tach.
Nineteen is offline   Reply With Quote
Old 06-06-2017, 04:31   #14
Registered User

Join Date: Apr 2017
Location: Winnsboro, Texas
Boat: Catalina 30 MKII
Posts: 262
Re: Adding engine total hour "Hobbs" meter / How?

Quote:
Originally Posted by Nineteen View Post
Any FBO or flying club worth its salt has seen this clever trick before and is onto would-be cheats.

Take a plane out for three days, and two hours shows up on the Hobbs - no real problem to compare the tach time and bill the pilot based on tach hours. Though tach time and Hobbs time do different somewhat, it's a pretty consistent variance and a "malfunctioning" hour meter won't stump too many FBOs for more than a minute or two.

A halfway bright pilot, AME, or even line man can figure out that the amount of fuel left in the tanks when the plane is returned is a pretty good indication of how many hours the engine has been run.

Then again, I suppose one could cheat on their taxes too. The IRS is so "clueless".
ValiantV is offline   Reply With Quote
Old 06-06-2017, 11:56   #15
Registered User
 
Nineteen's Avatar

Join Date: Apr 2015
Posts: 85
Re: Adding engine total hour "Hobbs" meter / How?

I used to have owners that would even try and hide hours - and thats how people get killed....
Cheers Tom
__________________

Nineteen is offline   Reply With Quote
Reply

Tags
engine

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Engine hour meter failing peterp Multihull Sailboats 33 17-03-2019 06:59
How Do You Calculate Battery Bank Total Amp Hour Capacity? spottsvillle Powered Boats 18 14-07-2016 17:40
Engine Hour Meter Greenhand Engines and Propulsion Systems 35 13-06-2014 17:31
Engine Hour Meter Erroneous Readings lwasouth Marine Electronics 1 03-09-2012 13:32
Discrepancy Between Engine Hour Meter and Reality lorenzo123 Engines and Propulsion Systems 17 25-11-2011 06:40



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 03:29.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2019, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.