High Output Alternator Repair

[supersailor]

Flat serpentine belt and pulley kits are also sold for these engines. I noticed them while shopping for my new "high output" 90 amp alternator. I think one of the places was AC/DC Electric.

Holly cow! You must have an electronic "forest" on board to use all that power! At full output that alternator will absorb a lot of horsepower.

 

[Jenkins]

How much power I wondered?

150 amp *13 volt = 1950 Watts = 2.6 hp

an exhaustive search on the web (looked at one document) suggests 50% might be a reasonable figure for an alternator efficiency.

so, about 5.2 hp!

peter

 

[footrope]

Designed for endurance rather than large continuous loads

Flat serpentine belt and pulley kits are also sold for these engines. I noticed them while shopping for my new "high output" 90 amp alternator. I think one of the places was AC/DC Electric.

Holly cow! You must have an electronic "forest" on board to use all that power! At full output that alternator will absorb a lot of horsepower.

We have a forest of wires behind the AC and DC panels, but you can see the trees. I attached some sample photos. There's no hot tub or anything, but the PO had a goal of going two days and nights away from shore power without charging the batteries. Using a mixture of halogen, incandescent and fluorescent lighting, a radio, the shower (water pressure pump, shower bilge pump) and domestic water for two days would put some demands on the storage and charging system. They liked their quiet as much as the rest of us. His solution was the extra house batteries and the large alternator.

The batteries are 13 years older now and we have added the diesel heater, which pulls about 3 amps at full fan speed. These days we really have to run the engine about every 24-30 hours. After two nights at anchor we are usually ready to move on anyway so the charging is sometimes done while motoring or motor sailing to the next overnight spot. Future plans call for some solar help and completing a conversion to LED lighting.

Vintage 2003 brokers photo. Nice AC and DC panels.
1990s Raytheon radar and chart plotter.


Behind the DC Panel. Labeled, waterproof, tied neatly.
The boat cables I added during the nav update are labeled on the white cover.


NMEA 0183 Signal patch strip before nav update. Note the ground bus on the left.


NMEA 0183 Signal wires patch strip after the 2014-15 nav update

 

[footrope]

Footnote on the Transient Voltage Suppressor (Diode)

I just put the boat back in the water after a month in a boatyard for bottom paint, keel epoxy barrier coating repair and rudder/steering system work. Along the way, during the steering system work in the binnacle, I shorted the compass light wires together while the switch was turned on. That blew a 1 amp glass fuse that also powered my Ample Power Battery Monitor (Electrical System and Amp Hour Monitor - ESAHM). At the time the battery monitor lost power I didn't know where to find the fuse. Searching through the installation guide and the installation schematic for the monitor, I found a reference sketch of an alternator and how to connect it to shunts, etc.

The TVS diode is called a "Snubber" in the attached cropped image from the schematic. It is not mentioned in the guide itself. I figure the PO, an electrical engineer, spec'd it himself and installed it. This closes the loop, for me, on why the component is in the system.

 

[Kenneth K]

I was thinking along the same lines as Jenkins--must be a lot of hp to drive that. He came up with 5.2hp (at 50% efficiency). If you could find the manufacturer's efficiency chart for your unit, it could give you further guidance for your battery charging regime.

A generic chart I found online shows typical alternator efficiency rising from 40% at 1000rpm to 55% at 1500rpm, and gradually dropping off to 45% at 3000 rpm (alternator rpm). At first glance, I thought that would give a horsepower range of 6.5 to 4.3 to 5.8 (as I stated in my original post). However, alternator output, and therefore horsepower-to-drive, drops considerably at lower rpms, so maybe its a wash in terms of hp required to drive. Anyway, if you had the chart for your alternator......might be nice to know.

If you're driving both your alternators at the same time, the effects will be even greater, and there would likely be some similarities in their efficiency curves.

(http://electronics.stackexchange.co...so-inneficient-relative-to-other-applications)​

Good for you for taking on such a guts-and-bolts project. It must feel great when you flip the switch and the light comes back on.....

Ken

 

[footrope]

Thanks for the link. The horsepower consumption calculation I could make is hampered by the fact that I don't know the make and model number of the large alternator. I have been told by the shop that it is a Powerline, so I could probably make a guess. For now, I have other items related to motoring speed and engine cooling that have to be resolved.

1. I need a new tachometer. The current one is so sluggish, particularly in cold weather (40 deg F) that I can barely use it up at cruise RPMs. I used to set it by boat speed with the older nav gear. but ...

2. I need to calibrate my new boatspeed system. I did not do this last year, but the recent motoring experience since the engine repair has shown a need to verify whether it is even close. See #1.

Another by-product of getting the boat out of the slip in winter due to "necessity" is that we re-discovered that if we dress right, we can be comfortable on the water even in 40 degree weather.