Alternator installation, noise supressor, resistive wiring

[Matt Cawthorne]

My Perkins 4.108 has a standard Delco-Remmy alternator attached to it. Besides the main ground and main current output terminal there are three spade connections. One is the signal for the tachometer. Of the remaing two, one is connected to the positive side of the starter motor with normal, stranded wire. The remaining wire disappears into the harness bundle. This wire is a fine, single conductor, resistive wire made from something other than copper. It is very long and is bundled up to keep it neat, but I think that the length of the resistive wire is there to introduce a specific resistance, and can't quite figure out why. This wire is a problem, because being a single strand of wire it cracks. Once or twice a year I loose the alternator and tachometer. If I fiddle with this wire, sometimes cutting out a questionable hunk and sometimes just bending it around a bit the alternator returns. Add to this the fact that the positive output goes to an unlabeled box on the side of the engine compartment. A heavy ground wire also goes to the box. A fairly small gage wire goes from the box to the common lug of the battery switch.

I am afraid of this little box because there are no ratings listed on it and I want to upgrade the alternator. Does anyone else with the Perikins 4.108 have such a box? If you don't do you have an electrical noise problem? Does anyone have some idea why this resistive wire is used on an alternator? Could it be part of a noise supression scheme?

I am tempted to just remove the box and lead a heavy cable from the alternator to the positive common terminal of the switch. I think if I did this I would replace the resistive wire with some stranded wire.

Any electricians out there?

Thanks,
Matt




mcawthor@bellatlantic.net

[Jeff Barnes]

My Perkins 4.108 has a standard Delco-Remmy alternator attached to it. Besides the main ground and main current output terminal there are three spade connections. One is the signal for the tachometer. Of the remaing two, one is connected to the positive side of the starter motor with normal, stranded wire. The remaining wire disappears into the harness bundle. This wire is a fine, single conductor, resistive wire made from something other than copper. It is very long and is bundled up to keep it neat, but I think that the length of the resistive wire is there to introduce a specific resistance, and can't quite figure out why. This wire is a problem, because being a single strand of wire it cracks. Once or twice a year I loose the alternator and tachometer. If I fiddle with this wire, sometimes cutting out a questionable hunk and sometimes just bending it around a bit the alternator returns. Add to this the fact that the positive output goes to an unlabeled box on the side of the engine compartment. A heavy ground wire also goes to the box. A fairly small gage wire goes from the box to the common lug of the battery switch.

I am afraid of this little box because there are no ratings listed on it and I want to upgrade the alternator. Does anyone else with the Perikins 4.108 have such a box? If you don't do you have an electrical noise problem? Does anyone have some idea why this resistive wire is used on an alternator? Could it be part of a noise supression scheme?

I am tempted to just remove the box and lead a heavy cable from the alternator to the positive common terminal of the switch. I think if I did this I would replace the resistive wire with some stranded wire.

Any electricians out there?

Thanks,
Matt

Matt:

The set-up you describe does not sound like a very pretty sight. It is possible that the coil of wire provides sufficient inductance to reduce high frequency noise. I have the 4.108 in my CD36 (#68) and recently replaced the Delco alternator and the entire wiring harness, although I did not have the mysterious box you describe, nor the coil of wire. I would encourage you to upgrade yor alternator to at least 60-70 amp capacity and install a three stage external regulator. in addition to providing faster and mor efficient battery charging, you will have a significnatly more reliable system.

Frankly, the Delco alternator and its internal regulator are hardly suitable for marine use. If you have any questions regarding wiring a new alternator/multi-stage regualtor for teh 4.108, please contact me.

Regrds,

Jeff



jt_barnes@msn.classic.com