After weeks of research and reading lots of Electronics “nerds” heated arguments of various forums across the globe, I’m beginning to see the light…   :D

Well, apparently while it looks like a simple choice between three numbers (12,24 or 48 volts), if the wrong number is picked, it can made the difference between “great” and “bloody hell”.

Now the motorhome as it stand, has the basic common design of two 12 volts battery in series for a 24 volts system, and it only seemed logical to continue to build on this path, therefore build the rest of the system (the motorhome side) on 24 volts. It does make sense, but is it really the best choice?

Is there anything in a motorhome construction that really dictate a specific voltage?
Why there are so many vehicle out there with 12, 24, 48 volts (and a mix of all three), instead of only one voltage across the range.

The answer become apparent as you start to investigate what the actual vehicle is used for. So to answer the previous question, yes there is. That’s good. So my voltage it is dictate by my intended purpose of the vehicle…. if it was only that simple…

Unfortunately, like everything else in life, it eventually become a mix of compromise between cost, performance and availability. I would like for the moment to concentrate on the availability. What we are looking at here, is the availability of devices that work on a specific voltage. Yes I know that we eventually will need to use voltage regulator and power inverters, but for the sake of the exercise I just would like to also to look at what are the best appliances to use in a Motorhome, their cost, their power consumption and their efficiency.

To recap, what we need here and in this order is to find out (based on our needs):

  • What appliances we’ll use
  • What appliances do work best in our environment and at what voltage they work best.
  • What appliances are available for the given voltage

Hmm… so, the voltage should be chosen based on what we use the vehicle for, plus what appliances do work at such voltage and if they work at their best, plus the availability of such appliances and their cost.

I think the best way to address all this would be to start to make a list.

What do I need, want or would like to have in my vehicle?

Big List:

Computer, Washing Machine, Fridge, TV, Dishwasher, Dryer, Air conditioner, Hi Fi Stereo, Microwave, Coffee maker, Toaster, DVD player, Hot Water system, Heater, Water pumps, Lights…

Old on.. That looks more like a house list than a Motorhome. If I got to take the same crap with me, may as well I can stay home…  ;)

Lets Cut the list to a more realistic one.

Laptop, Washing Machine, Fridge, TV, Dishwasher, Dryer, Air Conditioner, Stereo, Microwave, Coffee Maker, Toaster, DVD player, Hot Water System, Heater, Water Pumps, Lights…

Ok Ok, this is not working…

Well the washing machine is 240 volts as it is the Air Conditioner, the Microwave, the Toaster and Coffee Maker. I will need a Generator for these items, as I don’t think it will be fun to look for a 12 or 24 volts washing machine (way too small and way too expensive) for example, so may as well they can come off the list. Furthermore there are also appliances like the Heater and Hot water system that do come in an alternative fuel, so they can come off the list as well.

That leave us with a realistic lists of:

Laptop, Fridge, TV, Stereo-DVD player, Water pumps and Lights.

Now we are talking. This list is realistic and it also does offer choices as far as voltage goes. Two things to still keep in mind are: Does this device come in my selected voltage and more importantly, what is the power consumption of this device at that specific voltage. To clear thing up here a bit we need some numbers again.

For the sake of this exercise we will pretend that I have a choice of Fridge that work either at 12 or 24 volts. The power consumption is set at 200 watts.

Without going into excruciating mathematical details it is sufficient to say that this Fridge at 12 volts will required 16.6 ah while the same Fridge  running at 24 volt would required only half of that or 8.3 ah. It may doesn’t seem a problem now but it does become more apparent when we start to talk about the battery, their capacity, their charging rate and their duty cycle plus the other components required to complete the electrical system (fuses, inverters, regulators, wire thickness…)

Just from this little example we can clearly see that the higher the voltage we chose, the simpler and more effective the system becomes.

Now, considering that my vehicle already has 24 volts installed, like I said in the beginning, it just seem logical in my opinion to continue on this path. Using 24 volts should allow me to use my appliances and my solar system in a more efficient manner…

These are links to other sites where people have asked the same questions regarding best choice of voltage for a Motorhome

More info to follow…  8-)