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Electric Boat Conversions
There are various ways to accomplish what you want to do. You have to choose the approach to provide a safe, reliable, electrical, charging and propulsion system that makes sense for your boat and each boat will be different.
For example assume for a moment you want to power your boat with an electric motor propulsion system and two 48 Volt battery packs. You will need low voltage power (house load) for lights, bilge pump, radio, navigation electronics, horn, etc. You can choose to have separate battery power for the 12 Volt system or run a converter from 48V to 12V for your low house load power. Your choice will depend upon how confident you are in either approach.
Some people would recommend that a separate battery for the 12 Volt house load is a good idea because if there is ever a problem with the 48 Volt electric propulsion system you still have 12 Volt power for the radio, bilge pump, horn, lights etc.
Other people would say that a well designed and properly wired 48 Volt electric propulsion motor with large battery packs and a converter is as safe as it gets and your battery packs will supply both 48 Volt power to the propulsion motors and the converter will supply the 12 Volts for the house load.
There are some issues you need to consider that are important when you convert your boat to run on electric propulsion. The 48 Volt Battery pack wires that go from the battery packs to motor and motor controller should be kept as short as possible, be of the correct wire grade and size and keep the heavy voltage wires separate from the light voltage wires. Also, make sure you have a properly wired & grounded sytem.
I suggest using 2 battery packs connecting the battery cables thru main fuses to a battery switch (1/2/all) and then run the battery cables to the motor controller keeping these heavy voltage cables together on the left or right side of the boat. This will reduce and hopefully eliminate the electrical noise in your low voltage house current. Electrical noise can effect radio reception, navigation instruments, etc. You might want to run the low voltage house load wires on the steering console side of the boat and run the Battery cable wires on the opposite side to keep them apart. Typically, if the motor controller is mounted vertical or horizontal bow to stern so the low voltage motor signal control wires can attach to one side of the controller while the battery cables can be mounted to the opposite side of the controller. This is one way to keep the 48 voltage wires apart from the 12 volt house load wires.
You can choose many different ways to recharge the main battery packs and/or house batteries with the wind, sun, generators, etc. Are you running the generator to recharge the battery packs or are you running the generator to power the electric motors while running the boat? The different answers to these questions may require different switching electronics and controls.
I believe that a separate 12 Volt house load battery or batteries with a small wind turbine and/or solar cells for recharging is a good idea. If you want redundancy for the house load power include a converter to get 12 Volts from the 48 Volt battery packs. As far as charging the 48 volt battery packs I believe that solar cells or wind turbines would take a long time and the technology may not quite be there.
Inherently, electric boat propulsion is simple and straight forward.
I hope this has been helpful.
Last edited by JCR; 11-09-2009 at 10:31 AM.