alternator disengaging frequently, .5 seconds at a time

[evaneus]

My alternator seems to disengage, for around 1/2 a second at a time, on a regular basis, although usually after it's been running for at least a few minutes.
I thought it may have been caused by my solar panel interfering with the regulator but the same thing happens at night.
I have a Balmar 6 series (70 amp) alternator, and it is hooked up to a incharge/heart interface 3 stage regulator.
After it has been running for a few minutes, every 30 seconds to a minute or so I hear the revs spike briefly. When I look at my voltage monitor it shows the amps and voltage dropping off briefly when this happens.

Anyone know what could be causing this?

The charge is not high - not at float level. This is happening right now and I started the engine 10 minutes ago when the battery voltage was at 12.00 volts.

Thanks for any advice

[btrayfors]

My guess would be either a loose connection (on field wire, voltage sense wire, etc.) or the regulator itself.

When did this start? Did it ever work correctly?

Bill

[btrayfors]

Also could be a bad temp sensor (on batteries or on alternator), if you have them fitted.

I assume the belt is tight and not slipping :-)

Bill

[evaneus]

The belt is good, and so far can't seem to find any loose connections. I don't have temp sensors.

This is a fairly new issue, but I'm not sure how long it has been happening as I was underway a lot and getting good solar power so was not using the engine to charge.

I'll take a closer look at the connections. The alternator does seem very hot, but I really can't tell if it is above normal.

[Maddog47]

Take a look at the power line connection at the alt. Same thing was happening to me and it was loose. I was standing in the cockpit and saw it arcing with the engine uncovered. A quarter turn of the nut solved the problem. Check the simple things first.

[Stu Jackson]

I agree with the suggestions to check the connections. Almost every single one of the connectors that came with our new regulator ended up breaking after a few months of use. I re-did all of them.

[thekeip]

Why do you suspect an electrical malfunction at all??
h keiper
Berkeley

[evaneus]

It turns out it was a slightly loose nut, and a badly seated rubber boot. Before, I had only wiggled the connections and inspected them visually and they seemed fine, but the nut took a few turns and now all is well - thanks!

[btrayfors]

Originally Posted by evaneus

It turns out it was a slightly loose nut .... but the nut took a few turns and now all is well - thanks!

I'd say that nut was more than "slightly loose" :-)

More than half of my client boats I work on have loose connections, usually at the battery.

Suggestions to all:

1. get rid of any wing nuts on your boat....these are a no-no; inter alia, you can't get them tight enough.

2. clean and tighten all connections to your batteries; they need to be tight

3. check and replace any suspect lugs and terminals; you need clean and tight connections in order to reduce resistance and facilitate the transfer of electric power to onboard devices.

Bill