Portable generators like Honda and Yamaha are great quality machines and they do their job very well. Cummins Onan ‘confined space’ generators don’t directly compete with portable generators as they are designed for a totally different application.

Portable generators

Portable generators are just that, portable power solutions designed to be light, compact and portable. They excel at this job. They don’t work well in confined spaces, they are not designed for this and installation usually become messy. I have seen many ‘portables’ tucked into lockers with various vents and fans to help keep them cool. Then there is an exhaust issue and the associated heat from them. The cost of all these modifications usually offset the extra cost of fitting a ‘confined space generator’ not to mention any reliability, warranty and fuelling issues that stem from such modifications. Not all portables are electric start either.

Image: Honda EU30iS (3kw) portable generator mounted in a locker on a motor home. The Honda relies on additional modifications; a locker fan to achieve the required air changes to remove ambient hot air. Unfortunately it isn’t sufficient to keep up with the heat produced so the temperature in the locker increases to unsustainable levels. Also fuel filling is a definite issue especially when hot.

Cummins Onan generators

Cummins Onan ‘confined space’ generators are designed for tight permanent vehicle installations and can be run while the vehicle is moving. They have their own internal cooling fan which draws fresh cool air through the unit past the electronics, engine and exhaust (in that order). All heat and exhaust gases are discharged out and away from the cooling and combustion air coming into the unit, so the operating air temperature stays constant. You may not realise that as combustion air temperature increases, engine performance drops away hence a drop in KW output. Cummins Onan generators are designed to run in temperatures up to 49 Deg C. In addition, they have fault self diagnostic ability via the stop/start switch (KV2.3 not included). The small light on the switch will flash a code which can be checked against the manual to find the fault for an easy remedy.

Cummins Onan generators also come with their own starter motors, fuel pumps, mufflers & spark arrestors. Depending on the required fuel type, the fuel supply for the generator can be sourced directly from the vehicle's fuel tank - simplifying the installation. If the vehicle is diesel and a petrol generator (KV2.3 & KY 3.6) is required then a small cheap motorsport style fuel cell can be used. These are safe in a collision (won't split or explode) and come with fittings, fill cap and a rollover safe vent (see photo). The cost of fuel cells is about NZ$250-350 depending on size and they are available from most speed shops.

Image: Cummins Onan generators can be installed into a locker without compromising performance. We did an ambient air temperature test; the external air (outside box) and the intake air (at inlet vent on the generator inside box) differed by only 2 degree. Next to the generator is a fuel cell however the generator can draw fuel from the vehicle's fuel tank.

When it comes to permanently installed generators in vehicles, only Cummins Onan are designed for this use. I don’t think portables make the grade even when modified.

Benefits of Cummins Onan generators for permanent vehicle installation;

1. Compact and only requires 30mm ventillation around the unit without compromising performance.
2. Internal cooling fan efficiently draws cool fresh air through the generator taking away heat from electronics, engine & exhaust.
3. Electric start. As an added bonus we also supply the optional remote start as standard on all units.
4. Built in fuel pump allowing fuel to be sourced directly from vehicles fuel supply.

Below are a few images of Cummins Onan generators installed in mobile applications.