| Upgrading the Electrical Power System on Eaux Vives |
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Power to the People! Upgrades to Eaux Vives' power systems What was there?
Eaux Vives original equipment
To get maximum use of your batteries you should try to run them between 85% and 50% charged. (The last little bit is accepted too slowly and cycling below 50% will dramatically shorten battery life). This allows us to draw down (and replace) about 126 amp hours (.85 * 360 - 5 * 360 ). Running the engine for an hour twice a day won't really replace all that power because the batteries will not accept the 50amps the generator could supply. If we limit our power use to about half of that (60 amp hours), we are in pretty good shape. Eaux Vives with the two of us aboard, not reading late at night but taking regular showers, well within that range. We could run nav lights, pumps, radio and read after dark a reasonable amount. What was wrong?Our aging refridgeration system was leaking coolant and salt water constantly and the was deteriorating with constant "Island" patching.. Not only did it need constant repairs, it had a habit of spewing saltwater on the engine. It also had food rising and falling in temperature twice a day. Plus, we had to be on the boat regularly and listen to the racket a diesel engine makes. We decided to change to electric refrigeration. As Don says: "its a lifestyle issue!" With an electric compressor drawing about 5 amps and on about 1/2 the time, the one device will require 60 amp hours a day by itself. The advantage is that food doesn't spoil so fast (temperature is held constant rather than cycling all the time). We don't have to run the engine when power is available or when we want to leave the boat. In our case, The disadvantage: we needed more power both generation and storage.
You can get power from
In the Caribbean 110V 60Hz power is not always available. Eaux Vives originally came equiped with a charger with a feroressonant circuit for converting from AC to 12.5 volts DC. These are very hardy devices but the resonant circuit is tuned to the frequency of the power source to produce the correct power to recharge your batteries. We would rent a transformer (a great rusty hulking thing which easily weighed 50 pounds) and somehow get it to our slip (or even harder, to our corner of the boatyard). We would plug it into the marina's power and plug our boat into the transformer. While it would provide power to run a drill or the lights, it was not actually charging the batteries since it was running at 50Hz. We have since bought one of the Newmar smart chargers which will recharge the batteries according the the charge curve recommended for Gel Cell batteries and does not care about the frequency of the incoming current. While in Castries, St. Lucia we purchased a 2:1 transformer. These are readily available for home use in 220 V islands. I mounted it to a board and placed the whole thing in a plastic battery box to protect it from the rain. I then made an adaptor for the 3 prong plug found on the transformer to the round 30amp boat plug. At the other end, I made one of the round blue 220V plugs and added a length of wire to serve as an extension cord for the whole thing. . Most boats have just a little more line than it takes to get over the bow onto the ubiquetous (in the states) dock box. Here, the nearest outlet is never that close and, because it is higher voltage, the extension wire on the 220 side can be considerably smaller than 100 to carry the same current.. When I plug it in, fuses blow. After rains, the pwoer is out all over the islands and sometimes just in the boat yard. Sometimes there is a big charge for power connections. Sometimes The engine is used enough to serve as a big source of power. I added a second alternator to the engine (in the location previously occupied by the compressor for the engine driven refrigeration. I was unable to find any documentation at all on our alternator and took it to Electek in St. Martin to have its internal regulator removed so that I could attach it two a smart regulator from BSR. This regulator gives a little pause for the engine to come up to speed before phasing in the alternator to avoid a shock load on the engine. It then goes through a bulk charge, absorbtion and float charge cycle based on all sorts of occult calculations. It monitors battery temperature and alternator temperature. It has really cool secret code display that will amuse you and your friends for hours. We bought the Honda 2000 generator and just put up with the noise when the wind and the sun fail us. It is cheaper than running your engine and we need to carry gas for the dinghy anyway. Its quiet enough that it does not disturb the neighbors and stores in the lazerette easily. It does not heat up the interior of the boat as I run it sitting on the step through transom. When we need to use power tools, we can run the generator for power even when we can't run the engine (such as when on the hard in the boatyard). Regardless of what the brochures tell you, wind power really starts to kick in at 15knots. This is more wind than some people are really comfortable with anchoring in. It also needs to be mounted in such a way that laundry, body parts, lines & etc. cannot fall victim to the whirling blades. We have run around the windy anchorages listening to wind generators and came to the conclusion that the Aerogen 5 was the quietest. It is also somewhat expensive as you must buy a regulator and the total package is up to 1 1/2 boat units. On the plus side, it produces a lot of power and it runs whenever the winid blows. If you are on a sailboat, that should be much of the time. We find the Aerogen very satisfactory and I am now relaxed about running the autopilot while sailing. We have caught our fishing line multiple times in its whirling blades resulting in a tangle but no permanent harm. When we are sailing in moderate trades, we get enough power for the wind generator, nav lights and instruments. At night, it keeps up with the refrigerator if we are anchored in the typical trades but would not alone recharge batteries. Solar power is the bomb. It works all day. No moving parts. No maintenance. Free fuel. What's not to like. You need to mount the panel horizontally (in the tropical zone) and the mounting should be out of any shade. Your alternative is to mount it on swivels and re-aim it all the time. Much of the time, with boat swing, wind shifts, and heel, your panels will then be tilted the wrong way and all evidence convinces me to just get them out of the shadows of the boat and mounted flat.. We have been amazed at how well it works, particularly in conjunction with other power sources. The main reason is that the batteries get a nice trickle charge over a long period of time which can help condition the batteries and fill in that last 15% of the .batteriy's charge capacity. We get about 9 amps between 10am and 4pm on sunny days. Power Management
I bought a regulator for the solar panels which controls the flow of power into the batteries. We have gel cel batteries and must be careful not to cook them. Unlike wind generators, the solar panels will not be damaged by not having a load on them so these solar regulators are fairly light weight devices. Through mysterious powers unknown to me, many of them claim to get more power out of the sunlight that falls on your panels. OK. I wouldn't spend extra for this feature. Some wind generators have internal regulation, the Aerogen does not. All wind generators must have some way of protecting themselves against damage from too much wind. They have permanent magnets and so the coils are rotating in a fixed strength field. (Your engine alternator has electromagnets whose strength can be altered by the regulator) For this reason, power output by your wind generator will rise exponentially with the wind speed. The regulator cannot make that power vanish it can only manage it. A regulator can let power flow into the batteries at the charge curve that they like. It can protect the batteries from being cooked by shunting excess power to a couple of large resistors. In high winds, when the batteries are fully charged, the resistors will heat up and even buzz a little. This is better than heating your expensive batteries and making them vent steam. I have friends whose batteries were ruined in a single windy day on an unattended boat. In all cases, you should turn the blades out of the wind. Very high winds can destroy the mounting of your alternator, burn out its bearings due to exessive heat. There is one brand of wind generators which "feather" the blades to reduce output in high winds. They are very noisy and are not appreciated by anyone down wind of you and will still need to be hand turned out of big winds. Best suited for large farms. Eaux Vives has two alternators. One is internally regulated and supplies only the house battery. The second powers only the house battery bank and runs through a BALMAR regulator. I carry jumper cables if I need to combine the batteries for some reason. The engine is running right after the load of being started and the engine battery output goes from very high (30amps) to very low (>5amps) within 5 minutes of engine start. Usually I run the engine because we are uping anchor and will run it until the windlass has done its work. We no longer run the engine to make power. The resultsWe now have a system with three 4D house batteries for roughtly 540amp hours of storage. Roughly one third of this is usable (as per the calculations above) for about 180amp hours. This would leave a couple of still, cloudy days to pass without undue concern. Under normal circumstances, we have enough power to run the refrigeratior, lights and instruments as desired. We even watch movies at night and can run on the auto pilot without concern. We are enjoying the fact that the refrigerator provides us with cubes of ice with which we can impress our less fortunate neighbors and particularly enjoy the fact that the freeze/thaw cycle is gone. We are no longer spoiling as much food and we no longer brew a messy soup in the bottom of the box. Best of all, our engine usage has gone way down. Instead of about 400 hours per season in previous years, this year we used less than 100 hours. |
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An important principle in your power system is balance: between load, storage, and generating capacity. Originally Eaux Vives had engine driven refrigeration and no particularly heavy power draws. It had lights, water pumps, shower sump pumps, a VHF radio and an autopilot. The windlass is a big draw but it is always in use when the motor is running so its not much of a factor. The original storage configuration had one start battery and two "house" batteries run through a combiner. The original source of power was a slightly underpowered 50Amp alternator. Since refrigeration was engine driven, we were forced to run the engine a couple of hours a day to keep the food from spoiling. Power, though limited, was not a big issue since the batteries got recharge in the course of cooling the food. A system simple to fix and operate as befits a charter boat. A more subtle advantage is that the engine will be run to temperature regularly and will normally be run under load. Diesels hate being idled with no work to do and they don't like multiple starts without getting up to temperature. My only suggestion to improvements to this setup would be a somewhat larger alternator and the use of a solenoid switch to combine the batteries (attached to the oil pressure sensor) to avoid the voltage drop across the diodes that make up the "combiner". Gel Cell batteries also appreciate a more sophisticated charging sequence than the internal regulator for the alternator could provide. An external regulator might marginally lengthen batter life under this regime. 
The link 10 is a major source of amusement to me. It will tell you the net of current flowing into/out of your batteries. It attempts to act as a kind of gas gauge by tracking how long and how much power you have been taking out. This number, shown at left, is the total of the draw of all your running devices plus the total input of all your power producing sources. Since it cannot know exactly how much of the power flowing into the batteries has actually been absorbed by them, the gauge can drift a little bit off. In our case, it appears to err on the low side. If it senses that the batteries are not absorbing more power and are at full voltage for an extended period of time, it will actually just reset this running total to 0 amp hours drawn. The little red light/green light display serves as an eye catching idot light on how "full" the batteries are. Its main use is to alert you to excessive power draw. As in "Honey, the solenoid on the propane tank must still be on." Read my essay: