Regal Ambassador 255XL - weird DC load issue with accessories while on shore power

[Blueghost924]

Hi, I have a 1986 Regal Ambassador 255XL. I have a very weird problem occuring when on shore power (my garage extension cord plugged into the shore power connection). I have a 25W Marine VHF radio, a cigarette lighter and a Garmin GPS wired into the DC bus inside the electrical cabinet behind the center console. When I'm on shore power and the breaker shut for the converter, I turn on the Marine Radio and the Garmin. No problems. Then I turn on any of the other DC loads that came with the boat, such as any cabin light, the engine blower or the boat horn. What will happen is that the Marine radio will cut off momentarily then come back on. The Garmin will cut off. Attached is a picture showing the DC bus inside the boat. In the top left hand corner on the top bus nar is what appears to be the main red power coming from the converter. To the right (on the top bus bar) are the 3 loads I added (radio, cigarette light, Garmin). Of course, the regular boat DC loads (accessory toggle switches) are on the bottom section on the other side of the fuses. Yes I need to clean the bar lol. I'm also attaching a pic of the DC schematic from my manual that came with the boat.

For a different twist, I disconnected shore power and started up the engine to simulate being underway. I turn on the radio, used the lighter (USB charging) and GPS. I then hit several other DC loads like cabin lights, horn, bilge blower, etc... Smooth as silk with no interruptions to the radio or GPS.

Any thoughts? My initial thought was to buy a separate positive bus just for the radio, GPS and lighter.

 

[dingbat]

First thing you need to do is replace that fuse panel, it’s beyond cleaning. It’s shot

i suspect the terminations on the converters are in the same condition. They need cleaned up as well.

Have you tested the converter to make sure it’s working properly? A simple voltage drop test is required

Its not unheard of for marine power accessories to go bad after 31 years of service.

 

[Blueghost924]

Thanks for the reply Dingbat and i hear you about replacing the fuse panel. That will definitely be a priority job soon.

I went back and looked at the batter charger/converter located in the engine compartment. The wires go inside the case, so there's really no way to clean it's electrical connections. It's listed as 15A continuous and 20A max. Maybe that's one reason why on shore power I'm getting this problem? My alternator on my Mercruiser 350 is a new one rated at 65A.

 

[dingbat]

Thanks for the reply Dingbat and i hear you about replacing the fuse panel. That will definitely be a priority job soon.

I went back and looked at the batter charger/converter located in the engine compartment. The wires go inside the case, so there's really no way to clean it's electrical connections. It's listed as 15A continuous and 20A max. Maybe that's one reason why on shore power I'm getting this problem? My alternator on my Mercruiser 350 is a new one rated at 65A.

You're no where close to loading down a 15A converter. You either have a bad connection(s) or your converter is on the way out.

Looking the way it does, it wouldn't surprise me in the least bit if your fuse panel wasn't the problem

Lets try this..... connect a voltmeter to the positive an negative terminals in the converter. You should getting 12-12.6 volts out of it. Now try turning on your radio, etc. If the voltage from the converter stays somewhat constant and the radio drops out, th problem is in your wiring. If the power from the converter drops out, it's your converter.

 

[Blueghost924]

Ok, I hooked up shore power this afternoon and did some tests. There's no open wire connections at the converter (they go through the case) but I did some tests right at the fuse panel. Please let me know what you think of these:

First test I did was to remove the red converter positive feed from the fuse panel and ran a voltage check with my multimeter. The result was 13.1 volts. Here's the pic:


Next, I reconnected the red converter positive wire feed back onto the fuse panel bar. I then hooked up a positive jumper from the screw on the positive lead for the radio (on the same bus side as the main red converter wire), and turned on various accessories. The voltage drop I saw was the following:

Power on, no loads: 14.1 volts
1 cabin light: 12.46 volts
2 cabin lights: 11.9 volts
Marine VHF radio: 13.2 volts
Radio and 1 cabin light: 12.2 volts
engine hatch blower alone: 11.7 volts (yikes)
fresh water pump alone: 11.9 volts

Here's a pic:

One other thing I did was to measure voltage with power on but no assossories at the other bus bar side of the fuses. It also measured 14.1 volts...



I still plan on (real soon) replacing the fuse panel with new, but what do you think of the quick tests I did this afternoon? I do need to run the engine Friday for a quick timing check - maybe I'll re-perform the tests from engine power.

 

[dingbat]

Removing the red converter wiring and measuring the voltage is a good test.

You could have left the converter connected to the buss and measured each circuit at the output from the fuse.

Either way, you have identified the circuits pulling down the power. Next step is to identify what is causing the overload in each circuit. Start with the circuits pulling it down the most and go from there

 

[Blueghost924]

It's been raining for a while, but we had a break in the weather today. I started up and ran the engine, warmed it up and put it in idle. While in idle, I ran several DC loads at one time, such as the marine radio, the cabin lights and the engine blower. No problems - everything was rock solid. I still plan on replacing the fuse buses, however, looks like the converter may need a replacement in the future as well?