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Electrical PuzzlePlease help if possible

M

mcaboyd

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"I have a 2002 38' Regal w

"I have a 2002 38' Regal which has a persistent yet intermittant electrical problem (with apologies in advance that this is not specifically engine related but this is the brightest bunch of people I know!). When (and only when) the boat is used for 10 or 12 hours or more, and often 80% of this time spent at anchor with the Kohler generator running for several hours, the 60 amp circuit breaker at the main switch for my house battery trips.

So far I know the following:

-no 12 volt circuit is drawing excessive current per the ampmeter and combined they are no where near 60 amps

-I have switched breakers with the engine batteries and the issue still occurs

-I have made sure that the generator was not powering the battery charger with the thought that perhaps the charger, combined with the alternator on the Kohler combined sometimes but not always with the alternators on the Mercruisers was causing excessive charging current to the battery.

-There is no evidence that the wiring to the breaker (which is not massive or extremely heavy gauge) is getting hot, melting etc. as I would have expected with wire of this gauge and the thought of 60+ amps.)

-The issue has occurred with two different house batteries over the three years I have owned the boat and happens virtually every time I am out for more than a few hours.

-Unlike the breakers on each of the engine batteries which have one heavy (i.e. auto battery sized gauge) wire going to each side, the house battery breaker has an additional smaller gauge wire (i.e. 20 gauge) on one side.

The problem only seems to occur when the generator has been used. The panel is always very warm after such voyages but I think this is easily attributed to the fact it is located in the highest pocket in the engine room and would naturally trap heat behind it (it is accessed from within/under a cockpit seat)

In the three years I have put up with this while trying to fix it I have replaced the one smaller gauge wire mentioned above from the main house battery switch to the breaker which appeared too small a gauge with no improvement. I have never experienced the problem when the generator was not run on a trip though most trips of 10 hours plus do involve some use of the genny even if it is short. I have never experienced the problem when at the marina even running all 12 volt systems for days or weeks on end, hence my thought that the issue is related to charging.

Hopefully someone can shed some light on this puzzle. I am willing to try anything.

Thanks so much-Michael"
 
"Michael,

Are all circuits


"Michael,

Are all circuits fed by this breaker fed also by sub-breakers (not wired directly through this breaker with no other circuit protection)? If so, are any of these sub-panel breakers tripping?

These are thermal breakers, which means they trip at a set temp. That temp may be caused by the electrical current flowing through it but it may also be effected by the surrounding air temp. A 60 amp breaker will carry 60 amps at 70 degrees, but if it is in an environment that is 150 degrees, such as next to the genset exhaust or in the engineroom, it may only require 20 amps of current to generate the additional temp required to trip it.

Finally question, are you able to detect any type of spike on current or dimming of lights prior to the breaker tripping?

Hopefully by answering these question we will be able to pinpoint your problem.

Good luck,
Rick"
 
"Rick,

Thanks so much for y


"Rick,

Thanks so much for your suggestion which may hold the key to my issue. There are sub-breakers on everything I am aware of with the possible exception of bilge pumps though I have checked to make sure this was not the cause. None of these has ever tripped. However your comment about temp. is very interesting and is something I did not realize. Due to the position of this panel on my boat it is in the highest point in my engine room and is basically housed in a small area created by the hollow in the end of a cockpit seat between the outer wall and the interior wall of a cockpit compartment. As such it gets very hot when the boat is used for extended periods (which is of course when my problem always occurs).

The way it works it that this panel houses three large Guest battery switches and the corresponding 60 amp breakers for each all of which are accessed by removing a cockpit cushion so that the switches etc. are viewed/utilized from inside the underseat compartment.

I will remove the panel tomorrow as there are only eight screws holding it in and allow it to vent the heat to see if this makes a difference. I am sure it is at least 150 degrees if not higher in this "box" as I am in Florida in it is usually over 90 degrees without the benefit of two 8.1 HO Mercruisers and a generator running. It may be that the generator tie-in I have noticed is simply the added heat or just the prolonged heat without a break that pushes things over the edge.

I have no doubt that in addition to the heat I am usually running between 20 and 30 amps through this circuit and also sure that spikes from water pumps, vacuflush pumps for two heads or even the current sucking vent fans that can be switched on in the head will push this figure ever higher.

Thanks once again...I am optimistic and excited to give this a try. I will let you know how it goes!

Warmest regards, Michael"
 
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