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Thursday, 3 December 2009

TURNING GAS INTO ELECTRICITY - Using a gas powered Generator

I see no hookups!

This article was first published in MMM magazine in May 2007. I have revised it slightly to include further experiences with the gas conversion to our Honda generator and some more photos.

One of the well known challenges faced by motorcaravanners, who like us shy away from the well beaten track, is that of extending battery power to maintain required services, particularly in the winter season.

Until a boffin somewhere develops an inexhaustible 12V battery there will be only four basic options to counter this:

(1) Never camp more than 20 yards from a mains 230v outlet
(2) Weigh down your van with extra batteries, and/or –
(3) Invest large sums in a set of solar panels
(4) Buy a noisy, smelly generator!

The two other options; the wind powered generator and the fuel cell, are not for the lazy at heart or shallow of pocket, respectively. Wind turbines are constantly noisy, difficult to store, require a secure pole to mount them on and lots of attention if it gets too windy. Fuel cells cost upward of £3,000 and require methanol to run, at around £30 per 5 litre can – which of course is not readily available at your local garage.

For us, option (1) is generally a non-starter because we just like to be out in the sticks, though of course some CL’s fit the bill, and also provide a 230V hook-up.

Option (2) is out because we don’t have the room or spare payload. However, there is considerable gain to be had from better charging equipment over and above the standard alternator – Sterling or CTEK Battery to Battery (B2B) charger, for example, and also ensuring that the leisure battery is well insulated from the cold.

Sterling Power - a good source of DC info and products

CTEK - a fine range of 12V chargers and equipment

Option (3) I am a late convert to solar panels, but they are only of significant benefit in sunny climes – a case of diminishing returns when you need them most. For us they are an indispensable aid to autonomy, but not a guarantee of autonomy. When the battery breathes its last on a bitter, snowy night in the French Alps, a solar panel is as much use as a chocolate fireguard!

A solar panel's not much use in this!

Option (4). There are some who say (Sue might be one) that I am just a sad old retired seadog who is lonely without a generator to play with – well, who am I to argue?

Our generator in action in Albertville, France

My vote goes to the little red Honda, the EU 10i, which we bought in 2004. Shop around and it can cost less than a solar panel and installation. If necessary we can run our 500 W fan heater on it and (don’t laugh) our 800W mini vacuum cleaner.

It’s easily handled and extremely quiet – situated underneath the back of our ‘van it is barely audible to us inside when just charging the battery. It uses "inverter" technology which means it outputs a pure electrical sine wave (just like the mains supply) and so can be used safely with modern chargers, TV's and laptops.

Honda Generators

Before anyone pops up and says “what about the poor campers outside having to listen to it”? I entirely agree, which is why I have invested in a solar panel to avoid disturbing the peace on balmy summer evenings. However, when up a mountain it is generally only the wild life we are disturbing, and as they are used to cars and ski buses all day long, piste bashers at night and avalanche blasting in the early morning, it's unlikely they are going mind too much.

There's nobody else here but the animals

On the other hand, on a popular winter aire you just have to put up with the noise as everybody is at it (running generators, that is).

A crowded aire at La Rosiere - my generator's bigger than yours!

One more thing. I wanted to avoid carrying a third fuel, i.e. petrol (as well as diesel and gas) around with us. It is illegal in some countries to carry loose containers of petrol (that could include the generator), and always on a ferry. That it because is potentially dangerous to our own health and safety, as well as others. Petrol under the bed? No way.

So began the investigation into gas powered alternatives. I discovered that these fall into two camps, the replacement of the existing petrol jet with a gas jet “spud adaptor” (the Brown Power solution) or the fitting of a venturi flange or collar into the air intake (used by Edge Technology and others). The advantage of the venturi is that the engine can instantly be changed back to run on petrol and is effectively “dual-fuel”.

The disadvantage, so I was told, is that the little Honda engine doesn’t run as sweetly with this conversion – though this is the method used for vehicle conversions. As I had no intention of running on petrol, I played safe and opted for the replacement of the petrol jet with the gas version.

Both systems require a gas demand valve or fuel controller which, it has to be noted, are smaller than a can of petrol. You may baulk at his extra bit of kit as being too much hassle, but I have a stainless steel snap connector fitted to the hose, so I can quickly connect it to the BBQ connection under the ‘van.

Note the aluminum mounting plate to keep the demand valve upright

The under-the-van connection might seem a bit of a fiddle, but in snowy/icy climates it avoids the danger of the connectors getting frozen up in snowy/wet conditions. I have never had any problems despite repeated connections and disconnections at well below freezing – keeping them dry is the answer.

The priming pin is in the middle of the face of the valve

The generator also has a snap connector fitted to its hose. Setting up is therefore just a case of plugging the demand valve into the outside BBQ connection and plugging the generator into the demand valve – quicker and less hassle than getting the petrol can out really. A couple of squeezes to the pin on the demand valve are required to prime the system, then a few pulls and it’s away. The choke is not used, nor do I bother with the fuel shut off.

To shut down, a valve on the BBQ connection is closed. Then the hoses are swiftly separated, the generator goes under the bed and the demand valve into the gas locker.

Storing the geny under the bed next to the heater – something I wouldn’t dream of doing if there was a trace of petrol in it – means that on a typical Alpine night of minus 10º C, I can lift the machine out of its nice warm refuge and have it up and running outside before its had a chance to protest, though the air intakes did frost up a bit at 6500 ft and minus 15ºC!

I have no experience of the Edge Technology conversion, I can only say that our set up  has been 100% reliable and worked very happily.

Minus 15 C and altitude 6500 ft - still purring sweetly

One other issue which should be mentioned is running at altitude. I raised this question before purchase, as obviously for a given jet size the mixture is going to get richer as the air gets thinner. For a standard petrol machine, the Honda manual recommends that you change the carburettor jet at altitudes higher than 1500m (5000 feet) and you could consider buying a special jet for this purpose. Without the correct jetting, fuel consumption will increase and the engine will smoke.

However, the prospect of changing jets as we went uphill and down dale would, for me, put an end to it, and no doubt I would do as other winter campers seem to do – put up with the extra fuel consumption and pollution. The manual also points out that even with the correct jetting, the engine horsepower will decrease approximately 3.5% for each 300 metre (1,000 foot) increase in altitude, so if the output from your machine is intended to run heating or other high current device that is a factor you need to consider.

When I mentioned the altitude conundrum to the technician at Brown Power, he confessed that, for a gas powered machine, no one had asked him this before. He promptly came up with the solution of fitting a small globe valve after the supplied demand valve, to throttle in the gas supply as required. Some gas converted machines have a tendency to run unevenly on light load (mine is one), and this extends into rest of the power band as the mixture gets richer. To alleviate this problem, I just take a coin out of my pocket, put it in the slotted spindle of the globe valve and tweak it until the geny sounds sweet. It seems like a crude solution but it works.

I raised my concern that I could damage my machine by running it too weak (a hazard if you changed jets on a petrol machine up a mountain and then returned to a lower level) but he assured me that the fuel/air ratio is so critical for a gas powered machine that if it is too weak, it just won’t run.

Bearing in mind that Autogas (LPG) contains a mixture of Propane and Butane, the blend of which varies according to your country of location and even the season, it is perhaps remarkable that a unit designed to run on bottled propane can be persuaded to run as happily as it does, never mind at high altitude.

One last point, the length of the hose between the demand valve and the generator is critical to performance and should not be altered.

Running on gas: Advantages

Safer – no need to store and handle another volatile and toxic fuel.
Cheaper to run – even more so if you use refillable bottles and Autogas.
More reliable, can be stored indefinitely – no need to drain tank and carburetor to avoid a build up of fuel residue.
Environmentally friendly – no danger of fuel spills, and cleaner emissions.
Extended running times without refueling – 24 hours or more.
Cleaner exhaust, plugs and oil – hence maintenance periods can be extended.
Tuning for running at altitude can be simply accomplished.

Running on gas: Disadvantages

Initial additional cost of conversion.
Cost of installation of BBQ gas point or dedicated supply.
Demand valve/fuel controller must be carried, though smaller than a petrol can.

What price being independent to enjoy mornings like this!

System types: Carburettor gas jet (Brown Power)

This replaces the original petrol jet, removing the float chamber and other parts, and once converted the engine can only run on gas. (These parts are retained and can be refitted in a few minutes if you want to run on petrol). The petrol pipe should be blanked off to prevent accidental flooding.
The demand valve uses a reduced (regulated) supply so the BBQ point can be used for both purposes.
Available from:

Brown Power - dealer and conversion specialist

PetePower - conversion, repair and useful, humourous info!

System types: Carburettor gas venturi (Edge Technology)
This is an aluminium plate or collar which fits between the carburettor air intake and the air filter, requiring some extended mounting bolts. The engine can now be run on gas and petrol (but not both at once!)
The combined fuel controller/regulator requires an unregulated supply, hence you cannot use a standard BBQ connection, you will need a dedicated, unregulated (high pressure) supply.
Available from:

Edge Technology - dealer and conversion specialist

Postscript: We recently returned from a two month trip to the Western Isles. October and November not being the warmest and/or lightest of months I anticipated that the generator was going to get a good deal of use. The snag for us was that Autogas (our usual fuel) is only available in one location, in Stornoway, hence we were going to have to use the vastly more expensive and still less readily available Calor gas.

So, I gritted my teeth, bought a 10 litre plastic jerrican in the motor accessory shop in Oban and converted the geny back to run on that smelly, splashy, toxic (to us and plants) liquid fuel.

The jerrican found a home strapped to the frame on the bike rack, but the geny, as always, had to live under the bed. Obviously I allowed the geny to run the tank dry each time, but this still leaves a spoonful or so of petrol in the float chamber. This was quite swiftly decanted back into the jerrican by taking off the inspection cover and slackening of the drain screw with a stubby screwdriver (a plastic hose fitted by Honda directs it out through the bottom of the casing).

However, despite these precautions and the additional task of allowing the open petrol tank to vent and dispel vapour before closing it up, we still got the odd whiff petrol from the machine, particularly when it was warmed up by the Truma heater next to it.
Not dangerous from an explosive point of view, or probably from the toxic, but not pleasant just the same.

I was glad to convert back to gas!

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