pieter

I built a small one for motorhome use, have a look here. Pieter

Have a look here, it mentions : "Kereosene powered refrigerators need their wicks adjusted weekly and their exhaust flues cleaned regularly because of soot build-up from the relatively dirty fuel. Kerosene refrigerator manufacturers do not make their own wick-type burners. Aladdin® supplies all of their kerosene burners, so replacement parts are readily available. Model number is on the side of the burner or on the knob. Replacement parts are available directly from AladdinLamps.com ". So you might be able to source a burner there. The question then remains is whether the flue of a gas fridge (made for a clean fuel) will be suitable for paraffin. Pieter

I had one of those when working in Nigeria, worked a treat, even with sizeable freezer compartment. Expensive, though.

OK, just checked my rectifier. It is rated at upto 1000V, so that might be the reason I had no problems, rather than the voltage not sky-rocketing. Sorry for the confusion. Get you know! Indeed component choice will be crucial.

No can't get to both sides of the windings, although there are motors where you can (which means you could make them switchable between star and triangle), but they were much more expensive. Interesting idea about the solenoid. Can you get solenoids with a variable movement/output? For some reason in my mind they are associated with on/off, i.e. one position or the other but nothing in between. I am sure you are right re alternators, but the brushless motor and rectifier do fine without load.

The heatsink you see on the pic is the rectifier, it has no regulator (as yet). I regulate by manually adjusting rpm to give me the voltage I need. I think effective automatic regulation would need to include a servo to adjust the throttle. It seems very ineffective to have the engine run at full power all the time and just burn up the excess energy as heat. Pieter

The only figure I have so far is Honda's quoted consumption of 340 kg/kWh, which is just under half a liter per kWh. Haven't used it enough to have my own figures. Agree about the noise. Not convinced about the alternator giving a better output. Hi, The motor was £57 inc postage, the rectifier £6 plus £5 shipping from Hong Kong. Yes, it is a four stroke, so noise a bit more bearable than two stroke. The coupling was off Ebay,but you can get them here as well. The reason I went for a flexible coupling is exactely because of the point you make about the bearings on these little motors possibly not being very robust. I cannot comment on long term reliability yet, but on the forum I got the idea off one guy has been using his (slightly different construction) for I think hundreds of hours. 6.5 hp is much more than you need for 65A. I do agree that if you live on board fulltime and a generator is your sole or main source of recharging the batteries than this is not the solution for you. For me it is ideal because it is only for occasional use in addition to solar and mains hookup.

The NASA doesn't stop at zero, but starts to count up from there, which is one way it goes out of sync. E.g. I have solar panels and after the van (sorry, no boat) has been left for a few weeks unused you will get a pretty high positive Ah count. If you don't reset this to zero but just start using the thing from there, you will obviously get a totally inaccurate result. However, I find the NASA very usuable as long as it gets reset when you know you have a full charge and you start using/discharging the batteries. So, the crtics are right in that it is not a fit and forget device.

Thanks for your replies. The motor I used is a Turnigy 5065 Brushless 270kv, but I suppose any make will do. You would have to match the kv value (not kV kilovolt, but stands for rpm/Volt) to the rpm your engine does. I went for something that generated the required voltage for my batteries (14.4 V) at near the max torque rpm of the engine, assuming that it didn't need the (higher) max power rpm to generate the kind of currents I was after, which worked well. It is indeed quite noisy. I don't know how noisy or quitet the suitcase generators are, but this might indeed be noisier. Maybe the next step would be some sort of sound absorbing housing? Pieter

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

Thanks for confirming my suspicions. On the motorhome forum I read many people swear by B2B chargers, but I also came to the conclusion that the advantage mainly holds true for older alternators. Hadn't heard about issues with modern ECU managed engines.

Does this mean that a B2B charger (like Sterling) which relies on a higher voltage isn't really that effective? I thought of getting one (for a motorhome, sorry, just spying here), until I noticed that my alternator voltage isn't much lower than what the Sterling supplies. But looking at your comment, even the slightly higher voltage, whic would take the battery into gassing, wouldn't help much.

Works a treat with proper aerial. Try to get one with 2 tuners if you want to record a second channel whilst watching.

The load is normally a supply that gets switched off when the voltage drops below a certain value, to protect the battery from deep discharge.