Sailing for prolonged periods away from shore power is going to challenge the electric power system. Cruising yachts before the 1950s would not have bothered much with batteries. Lamps were fueled by oil and if there was an engine it would have a lethal but always exciting starter handle. A modern fully gizmoed cruising yacht has more demands for electrical power and the prospect of running the engine for three hours a day just to top up the batteries is an anathema to this boater.
Typical alternator wiring diagram
There are solutions.
- Upgrade the alternator
- Add more battery capacity
- Introduce alternative power sources, wind and solar.
- Install a smart regulator to control the charging process.
The first two really go hand in hand, increasing the capacity of the battery capacity by adding a third battery is a good idea but the charging time will increase proportionately. To keep the charging time the same the alternator needs to be upgraded. Since delivery, the boat has increased its battery capacity by 30% but the original 50Ah alternator is unchanged. To keep up with the new battery configuration I have no choice but to upgrade the alternator.
Alternative power sources seems like a good idea. They can deliver a trickle charge when the boat is not in use so the batteries are always topped up, ideal for weekend sailors. This would be useful but for the fact I will be using the boat every day. Even at anchor there will be consumption from lights, water pumps, radio and not least the laptop publishing the blog. The trickle charge will be swamped by the flood of demand. No, daily running of the engine can not be escaped but with the alternator upgrade at least the running time is reduced.
I once boiled the acid in one of my batteries. I had been on shore power overnight so the house batteries were fully charged. The engine had not been run for a while and since the starter battery was on a different circuit it wasn’t charged overnight. I then went sailing and had to use the engine a lot. The alternator charged all three batteries and the starter battery drew a lot of current while the house batteries were full and simply got too hot. No real damage done, other than a wrecked battery, but a lesson hard learnt. A smart regulator would have delivered power only to the batteries that needed it.
I will be visiting the annual London boat show next week so I hope to get some good insights into the best solutions. This is a great opportunity to get around different suppliers and pose the same question. I doubt I will get the same answers but I reckon I might just place the order for the alternator and regulator.
Hi Dave – Caron gave me your website. My partner, Liz and I are alsp planning a round UK sail starting next year so we have had similar dilemmas with regard to alternative power sources. We have been looking at Duogen which is both a towed and wind generator. Towed will produce 5-6amps at 5 knots which is pretty good. We have also been looking to add another battery so we have 3 domestic and will upgrade our alternator as well. Smart regulators seem to be the way to go. We have also started to swap out our halogen lamps below decks for LED. I’d be interested to know what you end up buying. Solar panels don’t give you much other than a trickle charge and only really work in summer with long days. You can get ones that work in daylight rather than sunlight which is essential in the UK!
By: Jo Fraser on January 21, 2010
at 4:06 pm
Hi Jo,
thanks for the message, I’ll look into Duogen. I have just 9 weeks to go so panicy feelings are beginning to set in! I’ll do another post about the electrics upgrade. I hope you enjoyed the site. I’m planning to buy a camcorder and make some films of my adventure posting clips to YouTube. — should be good for a laugh!
Dave
By: davequarrellsailsuk on January 21, 2010
at 5:21 pm