Inspired by a thread on a German motorhome forum (link, 34 pages when I last looked!), I decided to have a go at building a 12V petrol engine powered generator when I saw a suitable Honda engine on sale for below half price.
I am a motorhomer, normally just spying on you lot for interesting technical bits, but thought maybe someone would find this of interest. Obviously, for those of you with big (or even smaller) generators to run mains equipment like washing machines, this has no relevance, as it is only able to charge batteries, not generate mains.
The basic setup is very simple:
- a small petrol engine (normally used in strimmers)
- linked to a brushless motor as used in RC models; these work as generators when driven
- a 3 phase rectifier
- I added a voltmeter, but that is not strictly necessary
This gives a fairly light generator capable of I would guess 30A, although so far only tried it on slightly discharged batteries and got 15A.
The clutch is removed from the strimmer engine, and replaced by a flexible coupling.
A mounting plate is used to fix the motor.
The recitfier can be seen here.
It gives me a bigger charge current than a 230V generator driving the van's battery charger would. Obviously it doesn't give me mains electricity, but the main reason for me to have a generator was to charge the batteries, and this does that with a quality Honda engine, for a fraction of the price of a Honda generator.
As mentioned at the beginning, not my idea, but maybe slightly different implementation. You could do the same by coupling an engine to an alternator, but this would be less efficient and heavier (admittedly more an issue for a motorhome than on a canal boat).
Plus it was an enjoyable project.
Pieter