Voltage regulator problems

[mccartyj]

Hi. I'm new here so here's a little background. I am owned by a '61 triton (#329) with the original A4. It's owned me for about a year now. It has the old generator and voltage regulator.

Here's the problem. The charging system hasn't worked since I bought the boat. So after a year of sailing in San Fran Bay I thought maybe I'd better look into it. I found that the points on the regulator were not closing to allow the generator to charge. So I replaced the regulator, polarized the generator, started her up and everything worked fine . Ammeter shows about 15 amps, getting 15.5 volts at the battery,voltage rises and falls with rpm, problem solved, Wrong!. Problem comes when I shut it down. It appears that the points on the regulator are sticking shut and causing a dead short to ground which causes the regulator to want to burn up. I'm thinking the original regulator wasn't the problem in the first place and there is some other underlying problem. Any ideas as to why this would happen?

Thanks,
Jim

[Don Moyer]

Jim,

I recommend one of two approaches:

1) If your alternator and regulator appear to be in decent condition in terms of corrosion, etc., you can take them in to a local automotive alternator shop. They'll make quick work of sorting out what you actually have (whether the alternator and regulator are compatible, etc.) and give you an estimate for repair.

2) If your alternator and regulator turn out to require more than $100 for repair, you're probably better off replacing the older system with a modern alternator with a built-in regulator.

Don

[mccartyj]

Don,
Thanks for your input. I did solve the problem. I returned the new regulator to the parts store and replaced it with a third regulator. Everything works A-OK now.
Jim

[bputney]

Hi Don,

To the points earlier in this thread, do you have an "alternator with built-in regulator" recommendation? I assume it has to be ignition protected, correct?

I just have one deep cycle battery, not two batteries for my system. I have very light electrical needs, end nearly none when the engine is not running.

Thanks,

Brett

[Don Moyer]

Brett,

I enthusiastically recommend our Mando 55 amp alternator (http://www.moyermarine.com/cgi-bin/shopper.cgi?preadd=action&key=OVEL_01_130). We've been selling this particular alternator for over 9 years as a replacement for the OEM Motorola 35 amp alternator, and to my knowledge, not one of them has ever been returned.

Don

[rsanburn]

Hello,
This has been the year for my A-4 to seek repairs. I recently replaced the intake valve spring on #4 cly. It was a tight fit but was able to do it with out pulling the engine etc. It runs great , but when the regulator kicks in and the amp meter jumps to 30, you can see and feel the drop in rpm, and it sounds like its laboring. As soon as it kicks off she purr's and has more power than before. Is it time to replace the Motorola?

[Administrator]

I don't know how much horsepower is required to generate 30 amps with that Motorola, but it could be significant as a fraction of the horsepower produced by the engine at idle.

Your alternator may be fine, and you should be considering replacing or upgrading the battery instead.

Bill

[rsanburn]

The battery is almost new it tests out perfect. I have 3 batteries, 2 house 1 start. The house is on a a solar 22 amp solar etc. 2 100 in par, 200 amp, etc. the reg does the same on the house. I have tried separating the batteries. It still does it all the batteries test above 12.8 to 13.4. Could it be in the wiring? #4 standard marine battery cables all almost new with no corrosion. Is it the reg its self?

[Don Moyer]

It's quite normal for a 30 amp load to cause a bit of drop in RPM. Alternators consume approximately 1 HP per 25 amps of output. At idle, an Atomic 4 is only producing 2 to 3 HP, so an alternator would consume almost 1/3 of the power output of the engine to produce 30 amps. As a more realistic rule of thumb, cruising at around 1900 RPM, I can recall losing 50 to 75 RPM when our alternator kicked in to produce 20 amps to keep our refrigeration unit running on Water Music.

The regulator in your Motorola is designed to maintain 13.4 volts so your upper battery voltage of 13.4 volts (decaying to 12.8 volts over time) is really textbook. The greater question in your case is what is causing your 30 amp load to sustain. In my experience, the amperage should drop down to between 5 and 10 amps or so to maintain the charge once the batteries are fully charged.

Perhaps one of electrical engineers will check back in.

Don

[rsanburn]

Thanks for your imput. Could it be that the Alternator only charges at a full 30amps and is not charging the rest of the time? I will take my MAC tools Dwell/ Charge meter and test it at cruising RPM. Thanks again for your time and imput. Rod