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Old 09-13-2016, 10:20 PM   #1
rgano
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City: Southport, FL near Panama City
Vessel Name: FROLIC
Vessel Model: Mainship 30 Pilot II since 2015. GB-42 1986-2015. Former Unlimited Tonnage Master
Join Date: Oct 2007
Posts: 3,443
NexGen 3.5 KW Generator upgrade in 30 Pilot II

The Nexgen 3.5 in my boat, like just about everything else, was installed before the danged deck mold was added with no regard for eventual maintenance. So, when the crappy 12-volt Jabsco cooling fan for the electrical end quit recently (engine hours about 200) causing the wiring to it to burn up and fill the boat with smoke (because some fool never placed a fuse in the circuit), I was faced with having to remove the generator from the engine compartment in order to remove and replace the fan as well as its aged and holed plastic duct hose. I had to cut the exhaust hose and seawater hoses going to the siphon block because I could not gain enough access to their hose clamps. These were upgraded to better material and lengthened upon re-installation to allow generator removal in the future.

While others with this generator have told me it runs fine with the fan off, Nexgen says it will shutdown under a load without the fan running due to thermal overload. I am not interested in challenging what the manufacturer says, nor do I want to damage the long term health of the generator due to consistent overheating. I am, however, interested in NEVER having to replace the fan again.

The biggest part of the upgrade concerned changing the cooling fan from 12 VDC to 120 VAC, something that Nexgen told me would be a more dependable feature. Their reason for not doing this was the added complexity of a 120-VAC fan. The generator has no 12-Volt windings; so the battery charger needs to be run to prevent the fuel pump and fan from running the battery down over time. The fan is clearing a lot bigger load than the itty bitty fuel pump, and thus the battery charger can be run at a lower power factor or not at all.

Concern over possible improper voltages hitting the 120-VAC fan's motor during generator startup, lead me to investigate two options to start the fan after the generator had reached stable a running condition; running wiring to and installing a separate switch at the main power panel or installing a time delay relay back at the generator. I chose a time delay set to 30 seconds. With no room in the generator's sound shield, I chose to mount the relay on a small shelf I made out of formed plexiglass on the engine compartment aft bulkhead.

New fan is a Vents VK 100 fan rated at 162 CFM. Nexgen said to get a fan rated at 165 CFM to 250 CFM, but even the Jabsco 12-Volt POS was not rated for much more than 100 CF.

Time delay relay is a Schneider Electric model TDRSOXP-120V.

The old holed and cracked plastic hose air duct was replaced with aluminized flexible dryer duct.

Total cost of parts around $450, including $200 for new wiring harness and $100 for fan. Labor, including the two friend who helped me lift the generator out of and back into the engine compartment - ZERO.
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Rich Gano
FROLIC (2005 MainShip 30 Pilot II)
Panama City area
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