Has anyone else removed their voltmeter wiring?

[jrowan]

Good day,
I like many other C-30 owners still have the original Ampmeter wiring run from the alternator to this gauge in the cockpit, then run back to the starting battery. I know that I'm getting a huge voltage drop from this long, excessive length of wire. But I can't afford to buy an replacement wiring harness kit right now. My Amp gauge is old & inaccurate, & I don't need it cause I have a new battery voltmeter at the breaker panel installed anyway. My question is this, has anyone else just disconnected the wiring from the old gauge, shortened its length, & then connected it directly to the starting battery? I presume it would connect to the hot / positive side of the battery terminal. Any advice? Also what is the correct Amp / voltage output of the original alternator for the 5411. I believe its 55 amps, but what would be the correct volt output measured on a voltmeter? Thanks.

 

[Old Skool Neil]

Your intended modification is basically correct. I connected my alternator output to the + starter post. That way the battery switch can direct the charge to any bank or disconnect the alternator completely.

Be sure the wire is of sufficient size to handle the planned amperage. For example, my boat originally had a 35A Motorola alternator and Catalina's wiring harness used #10 wire for the charging circuit. Maybe it was #8, my memory isn't what it used to be. I replaced the alternator with a 100A Delco and at the same time bumped the wire up to #4.

Finally, the output voltage is dependent on the regulator's settings but should be roughly in the range of 14 - 15 volts. Decades ago 13.8 volts was considered optimum, these days ask two guys and get three opinions. 14.2 to 14.8 volts is pretty common.

 

[Stu Jackson]

You also need to fuse the AO at the battery. Some discussions about this concept are included here: http://c34.org/bbs/index.php/topic,5977.0.html

It includes many links to posts by Maine Sail.

If you have limited funds for the harness, consider this: http://c34.org/bbs/index.php/topic,5078.msg35943.html#msg35943

 

[Twice Around]

jrowan, Yup..I removed mine..I have the alternator output going directly to my old school isolator, and the output for that goes to post 1 or post 2 on the battery switch, all 4 gauge. This required an extra run from the alt. over to the isolator, as opposed to a short run to the big terminal on the starter, but I had the cable and it was already purchased. I put a voltmeter in the hole where the ammeter was.

Neil if it was the orange wire, I think it was #8...still puny though but prolly OK for a 35amp alternator. The run back on my boat had failed so the P.O. ran a #10 or #12 wire temporarily-permanent-jumper in there from the ammeter to the isolator. :neutral:

I do not have any fuses though. How big a fuse do I need for the Motorola 35amp? Do I put it on the output between the alt. & the isolator? Do I make it 35 assuming I want to protect everything else in case the alt. blows up? I probably should have some big fuses elsewhere too, but I don't. Guess it is never too late to add them..that was kinda the whole point of starting the boat re-wire...to do it 'correctly'. Guess it is time to put Nigel's book on the bedside table again.

 

[jrowan]

Thanks for the advice. I know i need to do this wiring change. Twice around: where is your isolator located? Is it original to the C 30 wiring or did you add it?

jrowan, Yup..I removed mine..I have the alternator output going directly to my old school isolator, and the output for that goes to post 1 or post 2 on the battery switch, all 4 gauge. This required an extra run from the alt. over to the isolator, as opposed to a short run to the big terminal on the starter, but I had the cable and it was already purchased. I put a voltmeter in the hole where the ammeter was.

Neil if it was the orange wire, I think it was #8...still puny though but prolly OK for a 35amp alternator. The run back on my boat had failed so the P.O. ran a #10 or #12 wire temporarily-permanent-jumper in there from the ammeter to the isolator. :neutral:

I do not have any fuses though. How big a fuse do I need for the Motorola 35amp? Do I put it on the output between the alt. & the isolator? Do I make it 35 assuming I want to protect everything else in case the alt. blows up? I probably should have some big fuses elsewhere too, but I don't. Guess it is never too late to add them..that was kinda the whole point of starting the boat re-wire...to do it 'correctly'. Guess it is time to put Nigel's book on the bedside table again.

 

[Twice Around]

jrowan,

It is not original..the PO added it. When I did the fat cable re-wiring this spring, I moved it from the engine compartment (batteries were to port in engine 'room') to inside the chart table since I also relocated the batteries to the stbd settee..the isolator is now between the battery switch & the alternator output, which now has a dedicated run over to the isolator with 4# cable. It is one of those old Hehr??? diode based passive isolators. I also have an adjustable regulator on the Motorola alternator to compensate for the 0.7 voltage drop, so I can still get 14.2v to the batteries.

Here's a picture of inside the "in progress" chart table and re-wire project