With winter on its way we’re starting to lose solar efficacy and need to think about how we’re going to get power whilst we are parked-up. We could plug-in, but we seldom go to places where this is an option. A wind turbine works, but only if it’s windy. How about a generator? How does that compare against running the vehicle engine to efficiently charge our leisure batteries?
For comparison I chose the Honda 1000i generator. It is quite small and light, so would potentially be the most practical generator for us. This generator has a maximum continuous rating of 900 watts. Our mains voltage battery charger has a capacity of only 600 watts and outputs approximately 40 amps. This would be a limitation on the generator, so there would be little point in getting a bigger generator unless we were to also buy a bigger battery charger.
The Iveco Daily 4×4 is designed to be operated while stationary with the engine running to power machinery from its two optional power take-offs. To assist in this, the cruise control can be used to set the engine idle speed. With the engine idling at 800 rpm, the leisure battery charges at 48 amps. However, if the idle is set to 1200 rpm the battery charge current increases to 54 amps. These figures are with the leisure battery state of charge at approximately 70%. If the battery is down to about 50%, then the charge current can increase to 80 amps – the big advantage of lithium batteries.
For the comparison I used my vehicle diagnostic computer to read the exact fuel consumption of the Iveco engine. For the generator I used the listed fuel consumption in the advertising material, factoring it down to correct it for the battery charge 600 watt limitation.
The table below shows the results:
| RPM | mg/Cycle | mg/hr | L/hr | Amps | Amps/Litre | |
| Iveco Daily 4×4 | 800 | 6.06 | 581760 | 0.47 | 48 | 102 |
| Iveco Daily 4×4 | 1200 | 5.46 | 786240 | 0.64 | 54 | 85 |
| Honda 1000i | At 900W | – | – | 0.67 | 65 | 97 |
| Honda 1000i | At 600W | – | – | 0.41 | 40 | 98 |
I was quite surprised and pleased to see that the Honda generator and the 3L Iveco Daily 4×4 engine have a comparable efficiency when generating power within these parameters. And when the batteries are discharged more than in the test above, the Iveco can supply twice the charge capacity of the generator. Needless to say, we won’t be buying a generator and will save the 13kg payload of the generator for something more important.
Update – 9 May 2021
We have been asked about the effects of idling for long periods on the DPF, so we did a test. We were parked for a few days at an altitude of 1360 m (4,462’) and on two consecutive mornings we ran the engine at fast idle, 1200 rpm, for an hour when the outside temperature was between 0C and 3C (32F and 37F). The DPF particle quantity went from 2.53g to 3.75g, an increase of 1.22g or 0.61g/hour. This is an insignificant amount, the maximum particle quantity that the DPF can hold is 60g!
Click here for our Cold Weather Overlanding page
We have now installed a Victron Buck Boost 100 amp DC to DC converter that will make idle charging three times faster! Click here to see more.
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