Our boat is an entirely 12 Volt boat with 12V refrigerator/freezer and no AC genset. We believe this is the best system for a cruising boat that will not frequently be dockside. Our daily electricity usage is in the range of 140 Ah but on passage with a hard working autopilot and nav lights or at anchor watching videotapes with microwave popcorn it can run to 200 Ah.
On a sunny day our solar panels will provide 60 - 70 Ah. Though we have them on a swivel mount we often forget to position them for best alignment throughout the day. The solar panels we have include diodes between EACH cell to prevent voltage loss from shadows but unfortunately this type is no longer made.
In a windy anchorage such as the Tobago Cays or Aves in Venezuela our wind generator will provide far more electricity than we need. In a normal Caribbean lee anchorage it may provide 50 Ah though in the So Pacific it will be less useful. We find our Airmarine wind generator a good compromise between noise and power. The new model Air marine is an improvement over our previous one.
Many boats use Heart and Balmar products as they have the best marketing however we believe Ample Power makes the best equipment especially their Next step regulator and EMON monitor. We also find the Trace inverter/charger superior to the Heart. The Trace is more robust and can handle 50 cycle power as found in Bonaire & Curacao. The Next Step regulator also has the ability to control two alternators which is a cornerstone of our system.
A Second Alternator
After 5 years cruising and particularly before heading to the South Pacific where our wind generator is expected to be less useful we were ready to break down and purchase a Panda genset. Even more than the tremendous cost we were bothered by the loss of lazarette space which for us is at a premium for storing scuba tanks and gear. While the AC Panda is a marvel the DC version is very low tech in its charging circuitry. On Ventana with no AC loads it is wasteful to run an AC genset to just charge batteries. Either AC or DC would mean another major boat system to maintain. After looking at the Panda and nearly every AC and DC genset on the market and being mindful of space and weight I finally thought "outside of the box" and came up with possibly THE BEST SOLUTION of any single item on the boat- a second alternator.
By adding a second alternator to our main engine I saved $ 9,000, hundreds of pounds, several cubic feet of storage , eliminated major plumbing and electrical overhauls and do not have a genset needing constant care.
The second alternator is mounted in front of the engine facing backwards. It necessitated a custom bracket welded to the engine mount, a modification to the engine compartment front cabinet and a slight cut out of one companionway step. The alternator is turned by a double 1/2" pulley and is controlled by the same regulator as the primary alternator. For charging the engine is run at near idle RPM of 1300. This produces an initial output of 175 Ah which drops to 150 Ah in a few minutes when the alternators heat up. Running the engine at idle with this heavier load is better for it than a light load.
Engine running time is now 45 minutes to 1 hour per day and uses less than 1/2 gal of diesel. On a day when we move the boat we usually run the engine 45 minutes anyway just to pull anchor and motor out of one harbor in the morning and into another harbor in the afternoon. During the 45 minutes we run the engine we are also running our watermaker, making hot water through the heat exchanger, freezing our refrigerator/freezer plates and topping up batteries. (The watermaker runs fine on batteries but produces slightly more water at the higher charging voltages).
The very minor downside to our system is that we do not have the total charging backup a generator would give us but with the solar and wind we can get by. For an outlay of $ 1,500 total and a cost of maybe 150 additional engine hours per year we solved our energy problems and lost no space at all.
The primary elements of the electrical system are:
Click on any photo to see a blow-up with captions
*Subsequent to our installation we saw the IP 45- Dreamtime with an engine driven refrigerator compressor mounted on a shelf/bracket on top of the engine. We feel this to be a better solution as the alternator in this spot will get more cooling air and will face forward meaning the engine compartment extension can be smaller.
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