For those of you with insomnia this should help.
Old phone man has articulated far better than I the requirements for a gen set. I am going to describe another system, why I am using it, etc.
There are a couple ways to get ac power, one is by an ac generator powered by internal combustion engines, wind, water, hydrogen, what ever.
In order to determine the size needed you need to know the peak load you will see, and size your ac gen set to that peak. For most of us it is when the air conditioners kick on, high load for a few seconds and then tapering off to the normal run condition, but during its operation again cycling the compressor off and on. Perhaps the microwave will be used during a compressor cycle, need to add that load along with all of the others to determine your peak load.
The reason for me repeating peak load ad naseum, as another technique using a ac inverter powered by a battery bank and/or charger to provide the dc to the inverter. In this case the battry charger can be a small diesel driven alternator that will provide dc to the batteries. The alternator needs to be sized to the average power used not the peak. The battery bank acts as a buffer to the system and provides power for the peak loads.
A far better description is at
www.amplepower.com and there are a couple of articles in professional boatbuilder magazine on this topic. (Issues are in my truck which is 1600 miles from me)
They system I have on my truck is as follows.
* A 3kw prosine inverter. Pure sine wave, with a built in 100 amp battry charger. There was discussion on this board about pure sine wave vs modified, and one thing not covered was an issue called the power factor. What you will find is it will take longer to cook in a micorwave with a modified sine wave inverter. Won't make a darn bit of difference on resisitive loads. Now the difference is in the who cares region.
* Feeding the inverter dc are 820 amp hours of agm batteries. 4 8D AGM batteries from xantrex on close out.
* The batteries are charged by 3 sources. One is the 100 amp charger driven by shore power in the inverter. The second is from an ample power genie battery charger. A single cylinder diesel turning a 175 amp alternator. (This little motor could also turn a air cond. compressor and be use like oldphoneman was discussing) The third source is from the main enging alternator. I have replaced the Delco alternator in the Volvo with an ample power 275 amp hour alternator, no 275 is not a typo.
Contolling this is a smart regualtor by ample power, and a battery monitor and controller by ample power.
The smart regualtor can charge batteries based on the particular charging protocal of the batteries. i.e. AGM batteries cannot be charged to the same voltage as normal flooded cell batteries, they wil die very early. The smart regualtor can charge the start batteries with the appropriate protocal for them.
The controller monitors the amount of current used and displays in the cab in real language how much capacity remains. i.e. 25% of capacity use.
It will also monitor each battery bank (house, and truck) and distribute the charging current to the appropriate bank. It gives priority to the start batteries.
It will automatically start the genie at a predetermined discharge level of the battery. (Software not quite there yet)
Again a far better description on ample powers site.
The reason for the agm batteries is they can handle rapid recharge rates. I can put all 275 amps off the main alternator into that bank and bring them up from a 50 % discharge in less than two hours.
I can also plug my lap top into the battery monitor and find out more than I ever wanted to know about the use, condition of the batteries , blah, blah blah.
On the rear of my bed are a shore power inlet, a shore power outlet (30 amp) and a 15 amp ground fault outlet.
Inside the compartment with the inverter is an ac distribution box, which provides the power to the cab and rear of the bed.
Going down the road I can have ac power on my fiver at all times if I want too. I will modify the fiver when I get it to put a shore power inlet in the horizontal surface under neath the bedroom, as close to the hitch as I can get.
Now why. first of all I want to boondock and this will allow me to do so. Second I am dangerous when I try to fix things so I bought what is argueably the most reliable equipment yo can buy to generate my power.
i am going to use this skiing where a loss of power can be fatal rather than an inconvenience.
Do I recommend this, heck no, I have never used it yet, it is just what I wanted to do.
Chuck