Athene Electric power

Electrical system

Examining a cable connection in the summer of 2016, I had to realize I could only make a vague statement where each cable leads to. This cable chaos, painstakingly created in 26 years after various additions and changes, required a fundamental renewal. One should at least approximately understand the electrical installation in one’s own boat.

The timing also suited the background of the battery replacement. So far 2 GEL batteries (a 135 Ah) supplied the onboard power system and a gel starter battery (70 Ah) the engine. The nominal capacity of 270 Ah sounds a lot, but in practice, a maximum of 50% can be used if you don’t want to ruin the batteries quickly. As 135 Ah are very tightly dimensioned, the capacity had to be significantly increased, especially for long journeys.

The redesign of the electrical system is based on the following considerations:

  • Sufficient battery capacity for longer distances, i.e. at least 500 Ah.
  • Batteries one person can lift (weight).
  • An autarkic power supply as far as possible.
  • Powerful charger with adjustable charging current for weakly fused shore power connections.
  • Inverter for sinusoidal alternating current to use the much better and more cost-effective 230 V devices on board.
  • Galvanic separation of the steel hull from the shore power unit.
  • Lowest possible electrical losses in cables and fuses.

These specifications initially led to the search for a suitable installation location. Previously, the electrical installation had been installed under several floor hatches. A little here and a little there inevitably leads to cable snarls.

Since the renewal of the electrical system should also be combined with the installation of a washing machine, only one spot on board as possible, our “bathroom” directly at the mast. Some people will think this is the worst possible space, humidity is the biggest enemy of every electrical system. The boat is generally nut dry, so is the “bathroom” thanks to a hatch for effective ventilation and an air heat

er that deserves its name. Since the manufacturers of the installed devices know the conditions on board sufficiently, the air humidity may not amount to up to 95% condensing. In practice, this means a sailing dripstone cave.

Very helpful in this context was the book by Reinout Vader, “Energy Unlimited”, which I would like to recommend. (Download)

The complete electrical system in detail: