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Jack Goff

On Thu, 13 Jul 2006 14:38:35 -0400, wrote:

On Thu, 13 Jul 2006 13:30:51 GMT, wrote:

Greetings,

I have a Westerbeke 4.0KW gas genny in my boat, and I'm experiencing
the following: The genny runs like a sewing machine, and when first
started, the voltage settles right at 115. When a load is presented
(A/C for example), I'll get the typical drop from the load while the
genny adjusts, and then the genny will settle back to around 115. All
is well at this point. The problem is, when the load is removed (when
the A/C cycles), the voltage rises to 150 and stays there. I notice
an increase in engine speed as well.

My initial thought is that the voltage regulator might have gone
south, but I don't know if this would explain the rise in engine
speed. I guess if the regulator doesn't control the voltage, the
engine speed will rise accordingly to satisfy the higher voltage, but
I'm no electrical engineer, so it's just a guess.

Any input would be greatly appreciated! I'm planning an anchor-out
this weekend, and with the rains and heat/humidity in FL, I can't be
without A/C!!!

This is an alternator so engine speed only affects frequency. The
regulator may in fact be bad but if it really increases engine speed
there is another problem. I would suggect getting it looked at by
someone with the tools to see what is really going on.

You don't get the power for free, so under load the gas engine driving
that alternator/generator must increase its throttle setting to keep
up with the increased demand. When the demand goes away, the throttle
evidently isn't closing back down, and the engine speed increases
without that extra load on it. If poorly regulated, that can increase
the voltage output as well. Think of your car idling with the lights
on, the rev it up... the lights get brighter. Conversely, keeping the
same engine speed turn the headlights off, and the voltage will rise.

Does the engine speed ever slow back down on its own? Could it be as
simple as a broken/missing throttle return spring? Or maybe a binding
throttle linkage.