As I originally intended when designing the engine for my sailboat, I was going to put a gas generator in order not to depend on shore outlets in long crossings. The batteries on my boat are enough to go on the engine only for 64 km (I found out in practice, more details here). But it happens that there is more distance between the shore outlets or in bad weather conditions make it necessary to use the engine for more than economical run - then there is a need for a onboard generator.

I chose from two options, about them below.

Inverter Generator

1.6 kW inverter generator

1.6 kW inverter generator
Put the standard inverter generator (1.6 kW) and connect it to the battery through the charger.

This option had the following benefits:

  1. He took and bought it - it remains only to install it inside the case and make him exhaust and cooling.
  2. The charge is controlled by the charger - no need to monitor the voltage on the battery to turn off the generator in time.

And such disadvantages:

  1. Initially expensive, because such generators cost a lot.
  2. Relatively low power (since there are a lot of losses on many energy conversions gasoline -> 400V DC -> 220V AC -> 36V DC battery)
  3. General lower reliability due to the large number of electronics.

Gas engine

Engine 6 hp, gasoline

Engine 6 hp, gasoline
Use the gasoline motoblock engine, connect it to the generator and charge the battery through rectifier.

Benefits of this option:

  1. Initially cheaper. Such engines are relatively cheap.
  2. More power than an inverter generator of comparable weight.
  3. Less energy conversion and therefore more efficiency of the entire system.

Disadvantages such:

  1. More work for installation.
  2. A smaller ICE resource than in an inverter generator.
  3. It is necessary to monitor the voltage during charging in order to turn off the generator in time. This can be eliminated by adding a not complicated circuit that shuts down the generator when the defined voltage is reached, but I have not done so yet.

I chose the second option, because it was more interesting to me. Tinkering with cooling and exhaust had a good time. The pipes used to supply air to the internal combustion engine and to remove hot air outside the boat, as well as a water lock in which hot exhaust and sea water were mixed, after which this mixture was pushed outside the boat behind the stern (wet exhaust).

In the end it turned out like this:

And it worked like this:

And another video on which you can evaluate the noise level:

The generator worked in two long transitions, in the first 5 days it worked for 8 hours, in the second - 10 hours for 6 days.

Conclusions on the operation of such a generator:

  1. A good inexpensive option for the "dokatka" in the case of a long (over 65 km) transition in calm conditions.
  2. Pretty reliable and easy to maintain. There were no special problems with it - a very simple design.
  3. The need for it work in a long transition is only about 2-3 hours daily. The rest of the time the boat goes quietly on batteries.
  4. It releases a lot of heat - it is difficult to remove all this heat outward by air cooling way.

In order to be able to quickly charge the battery in a couple of hours with high power, the battery must be of a lithium type. A lead battery needs to be charged for 8 hours, so this type of hybrid with lead batteries is not relevant. Lithium normally refers to a full charge in 2-3 hours, it is not harmful to it.

What I want to do in the future

I want to try to use a diesel engine instead of a gasoline, because it has a longer resource compared to gasoline and less heating during operation, which will simplify the heat removal from it by air. In addition, a diesel engine for a walk-behind tractor is not much more expensive than a gasoline one.

I considered the option of a water-cooled engine, however, this will not be a budget option, so I will not try it yet.

About the conversion of the generator to a diesel engine will be in the next article, thanks to everyone who read :)