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A recurring theme of these articles is the power necessary to run our boats with all of the creature comforts we have become used to. As a result, the electrical systems on our boats have become complex. All of our boats have shore power connections, batteries, battery chargers and alternators on the engine. In addition, several of us have alternate forms of power generation equipment.
When we plug our boats into shore power which is alternating current (AC) we usually turn on the battery charger. The battery charger converts the AC to direct current (DC) and charges the batteries. DC is used to run everything on the boat; a few exceptions are the microwave, air conditioner and perhaps other appliances that we may plug into an AC outlet. Most modern battery chargers are “smart” in that they have complex charging and battery maintenance cycles. Each battery chemistry type has different charging and maintenance voltages, therefore you should never mix battery types in one system. The charger on Indulgence has a maximum rate of 40 amperes. A smart charger will run at the maximum rate until the battery is about 75% charged and then less until the battery is fully charged.
Great, for those of us whose boats live at the dock! What about those who are on a mooring? The shore power cord is not long enough, so we run the engine with the alternator and charge the batteries! However, the standard systems on our boats are not very efficient at charging the batteries. The problem is that while the alternators are capable of generating 50, or even 80 amperes per hour, the built in regulators shut the alternator down, so the typical output is about 20 amperes per hour. If you are like me, using 100 amperes hours per day, you would need to run the engine for 5 hours to fully charge the batteries. So, what do we do? We spend tons of “Boat Bucks” on alternative and supplemental power generating systems!
Here is some alternate and supplemental power generating systems.
- A high output alternator and smart regulator will generate 80 – 110 amperes per hour when the engine is running at low RPM. Indulgence has such a system and I can fully charge my batteries in about an hour. This system will replace the standard factory supplied equipment. Typical cost for a sophisticated system could be $1,000.
- Wind Generator: They have big (46” diameter) blades typically mounted on a pole at the back of the boat. Output will vary from 1 ampere per hour at 8 mph to 16 amperes per hour at 28 mph. At this rate it would take us 6 ¼ hours to get us the 100 amps we use, however, it runs continuously in the breeze. The down side is there is no output at low wind speeds and they make noise. Typical cost for this system is $1,000 to 1,500 with the mounts.
- Solar Cells: Solar cells are getting more cost effective, but they are still expensive and very large. A small solar is a great solution for a boat on a mooring, with nothing running, and only needs the battery topped up. Obviously they only work well when the sun is shining. However, for the magic 100 ampere hour per day capacity, we would need 2 or 3 large panels, weighing a total of 90 pounds that could mount on the dinghy davits or on top of the bimini. A perfect solution to mount the panels would be on top of a hard dodger, if you had a hard dodger! Total cost of the system would be about $2,500 to $3,000 including mounting hardware.
- Auxiliary Generator: There are two kinds of auxiliary generators: Built in and portable.
Built in Generator: This is the best solution terms of all of the power that you need. The generator can run while the boat is underway or anchored. Air conditioning, hair dryer, microwave, you name it. They are extremely quiet. However, they can typically cost $7 – $10,000.
Portable Generator: This is a good balance between cost and performance. I keep a Honda portable in my lazarette. I can charge my batteries in about 2 hours or run the engine and the portable generator for about one hour, charging the batteries and making hot water. The cost for a Honda portable is under $1,000. The 2 KW Honda is the smallest that will work on the boat. If you have a high output charger, working at peak, you may still have trouble making hot water and charging the batteries at the same time.
Battery chemistry is an involved, complex subject that is not appropriate for this article. Here are the highlights. You should only have one type of battery in your system as each type of battery has different charging and maintenance voltages. There are three types of deep cycle batteries used on our boats;
- Flooded: These batteries require maintenance in the form of refilling with distilled water. They are the least costly of all the battery types. They are rated with the lowest number of charge / discharge cycles. However, with a good charger and proper care they can last several seasons.
- Gel: Supposedly submersible with the greatest longevity. Typically three to four times the price of the flooded type. They have a higher rating for charge / discharge cycles than flooded batteries. Absorbed Glass Mat (AGM): High performance with maximum ruggedness. Roughly the same price as Gel, 3 to 4 times the price of flooded batteries. These batteries supposedly have the highest rating for maximum charge / discharge cycles. These batteries can easily last for eight plus years with proper care.
No description of batteries would be complete without including 6 volt golf cart batteries (connected in series) to get the equivalent 12 volt battery. However, the cost for two 6 volt batteries is approximately the same (depends on chemistry and brand) as a single 4D size 12 volt of equivalent chemistry. The advantage of the golf cart batteries is that they have a higher ampere hour rating (more useable power) and weigh half of the large 4D size batteries.
So, what is best for your boat? The answer is a system that is tailored to the way you use your boat balanced with your capacity for spending boat bucks. As a LISCA member you have the advantage of being in the company of boaters who have a lot of knowledge, experience with all of the systems
that we have discussed, and an unbelievable passion for wanting to help you decide what to do. I can tell you from personal experience, the most fun is to go through all of this stuff while someone else is paying! Let us know how we can be of assistance.
Special thanks to Warren Elliot for his contribution to this article. I consider him my technical alter ego.
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