The weight savings in wire alone will be about 7lb. ![]() The 24V version will require 8 gauge wire. Assuming a 10 percent voltage drop, the 12V version will have to be supplied by 2 gauge wire. Imagine installing a beefy 1,800W windlass on a boat where the wire run will be 48 feet (24 feet up and 24 feet back). Items like windlasses, large watermakers, bow thrusters, and large inverters draw so much power (and may be located far from the batteries) that using adequately-sized 12V wiring becomes impractical. The justification for using 24 volt equipment on your boat gets more compelling as the size of the DC loads increases. Applying the equation V (voltage) = I (current) x R (resistance), we get V = 20 amps x (30' x 0.00175) = 1.05V, which is less than 10% of our 12 volt circuit). Our catalog lists the resistance as 1.75 ohms per 1000', or 0.00175 ohms per foot. (As a brief aside, we can calculate the voltage drop in this circuit if we know the resistance per foot of 12 gauge wire. Looking at the intersection of 20A and 30 feet, 12 gauge wire is recommended to keep the voltage drop under 10 percent. Since we’ve got a 50 footer, let’s say that it is 15 feet from the battery to the pump, and 15 feet back from the pump to the battery, for a run of 30 feet. Larger wires have less resistance, just as larger hoses have less resistance when pumping water. But there’s one more thing that we have to know before selecting the correct wire: how long is the run from the battery (or switch panel) to the pump, and back? Every foot of wire adds a small amount of resistance, and resistance causes voltage drop. The American Boat and Yacht Council (ABYC) E-11 standard recommends no more than a 10 percent voltage drop for this type of circuit and points the installer to Table X, where the recommended size of wire can be determined. In the case of a bilge pump, we obviously want it to pump as much water as possible, and incremental voltage drop will cause lower performance (less water pumped). In a boat with a 12 volt electrical system, this pump would draw 240 watts ÷ 12 volts = 20 amperes of electricity. Bilge pumps of a given capacity will use a DC motor that consumes a certain number of watts to operate in this case, we’ll assume the pump consumes 240 watts. ![]() No component is immune from contributing to this phenomenon, but voltage drop can be measured and managed, and correctly-engineered boats do not usually suffer from it.įor example, let’s imagine a simple electrical circuit with a battery, bilge pump, wires, and a switch (and for the moment, let’s assume that the switch has no resistance and does not contribute to voltage drop). Voltage drop occurs due to the electrical resistance in wires, connectors, switches, and other conductors in an electrical circuit. ![]() That’s because it becomes increasingly difficult to avoid voltage drop-the nemesis of boat wiring systems-which can make electrical devices function less efficiently than you’d like. The main reason for this is due to boats having used automotive- and industrial-based components which are also based on a 12 volt standard.Īs boats get larger-say in the 50–60 foot range-and operate DC loads which require more power with wire runs getting longer, 12 volt systems start to become inadequate or at least challenged. That is, they use a battery that has a fully-charged potential of 12.6 volts, and the loads and charge devices that are installed on the boat are designed to operate between roughly 12 and 14 volts. Virtually all boats under 40 feet or so that have an electrical system operate at a nominal voltage of 12 volts.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |