Re: Is a demountable the right choice for me?
Posted: December 8th, 2016, 9:22 pm
As I mentioned above, I have been pleased with my 2007 Ranger supercab.
Jim noted that his Ranger has plenty of power, and if you look at the 2007 it is significantly more powerful than Jim's - so that should give you a fairly comfortable feeling.
Supercabs are more difficult to find than double cabs, but as I said before, if you don't need to carry extra adults regularly, the ability to load the camper further forward of the axle makes a big difference to weight distribution and reduces bending stress on the chassis. Whether you go for a supercab or double cab, make sure you get a camper that is suitable for it - you don't want lots of camper hanging out of the back of the pickup. So a supercab will allow you to safely carry a bigger camper than a double cab. The trick is to look at a camper on a pickup truck and in your mind's eye try to visualise where the centre of gravity of the camper is (find some pictures of campers and practice - you'll soon get your eye in and be able to spot ones with poor weight distribution - they just look wrong once you know what you are looking for). You want that centre of gravity over the rear axle, or ideally slightly ahead of it. You will find that in most cases it is probably slightly behind the rear axle. If when you look it appears to be way behind the rear axle then that is putting too much stress on the chassis and risks cracking it. If the camper looks about right on a supercab, then it will likely be wrong on a double-cab (CoG too far aft).
Solar: This is a good idea. If doing it don't mess around. You're going to have to drill holes, fit cabling, buy a controller, etc. So there is no point putting a small wattage panel in and then going back and adding another one when you find it is insufficient. I have 2 panels totalling 160w. I suggest something similar or greater than that. Remember that my panels will generate 160w when clean, at mid day, on the equator! If a bit dirty on a partially cloudy day up here at 52 degrees north in late afternoon in September you'll be getting a fraction of that.
Things you need:
Really thick cable: Don't be fooled by saying "oh, it is 10 amps, so this 2-core mains cable will be sufficient". The amperage rating of cable is to ensure the cable does not get so hot at the rated amperage that it starts a fire. But mains cable is thin enough that it will cause a resistive loss, even if not so much that it gets the cable hot. And you cannot afford to squander your hard won solar power on inefficient cables. Proper solar panel cable looks closer to starter motor cable in diameter (OK, maybe not that thick but you know where I am going) - to minimise the resistive losses. And while you are at it, keep that cable run as short as you can. Double the length of cable and you are doubling the amount of power being lost through the cable.
You need a solar charge controller. Get an MPPT one. These eek the most power out of the panels, while the cheaper PWM controllers waste power because they cannot convert it due to their simpler electronics. I have a very good CTEK D250S DC to DC charger. It is an excellent piece of kit - one side connects to your truck (without needing a charge relay), a second side connects to the solar, and the output goes to your camper battery. It then optimises power coming from the truck alternator and solar and feeds it through a built-in multi-stage intelligent battery charger to your camper battery. If the truck isn't running it doesn't drain the truck battery. If the camper battery is full and it has spare solar it charges your truck battery from the solar . About £200, but worth it.
Isolator: Fit an isolator so you can disconnect the solar power to the solar controller, in case you need to do maintenance on the system during daylight.
Battery: If you can fit 2 batteries in parallel then perfect. Ideally a couple of hundred amp hours in total. Don't mix battery types, sizes or ages. Get at least a "leasure battery", but expect to have to replace every few years. Proper deep cycle batteries are expensive, as are AGM batteries, but can be discharged more deeply and more often.
Battery monitor: Without one of these you have no idea of how much charge remains in your battery. And if you don't know the state of charge you are in danger of either overestimating and running the battery below 50% charge and killing it (unless it is an expensive AGM or lithium), or underestimating and sitting in the dark even though you had plenty of battery power. You can buy a cheap battery monitor that just reads voltage (or just read the voltage using a voltmeter and work it out), but for those to work you need to turn off everything that is pulling out of or charging the battery. If it is daylight the solar will be pulling the battery voltage up and will therefore cause the battery to look fuller than it is; if you are running lights etc then they will be pulling the voltage down. A better bet is a device like the Victron monitor I use (about £100). It measures the amps going in and out of the battery, and once programmed with the battery size can keep a track of its state of charge. So whenever you look at the display you can see how much power is left and therefore if you need to ration your use of electricity. Knowledge is power
Consider what is using your battery power: Change any incandescent bulbs in the camper to LEDs. Avoid running stuff off inverters unless you have to. Consider if you need to charge camera / phone batteries now, or wait until the truck is running tomorrow. If you can do something using propane rather than electricity, use propane. But the big killer is compressor fridges. I like compressor fridges - they work like your fridge at home, get cold quickly, maintain a temperature even in the hottest climates and work even when parked at 30 degrees. But they draw a lot of current - maybe 6 or more amps when the compressor is running. A propane fridge, as traditionally used in caravans, lacks the above advantages, but won't drain your battery.
Steve.
Jim noted that his Ranger has plenty of power, and if you look at the 2007 it is significantly more powerful than Jim's - so that should give you a fairly comfortable feeling.
Supercabs are more difficult to find than double cabs, but as I said before, if you don't need to carry extra adults regularly, the ability to load the camper further forward of the axle makes a big difference to weight distribution and reduces bending stress on the chassis. Whether you go for a supercab or double cab, make sure you get a camper that is suitable for it - you don't want lots of camper hanging out of the back of the pickup. So a supercab will allow you to safely carry a bigger camper than a double cab. The trick is to look at a camper on a pickup truck and in your mind's eye try to visualise where the centre of gravity of the camper is (find some pictures of campers and practice - you'll soon get your eye in and be able to spot ones with poor weight distribution - they just look wrong once you know what you are looking for). You want that centre of gravity over the rear axle, or ideally slightly ahead of it. You will find that in most cases it is probably slightly behind the rear axle. If when you look it appears to be way behind the rear axle then that is putting too much stress on the chassis and risks cracking it. If the camper looks about right on a supercab, then it will likely be wrong on a double-cab (CoG too far aft).
Solar: This is a good idea. If doing it don't mess around. You're going to have to drill holes, fit cabling, buy a controller, etc. So there is no point putting a small wattage panel in and then going back and adding another one when you find it is insufficient. I have 2 panels totalling 160w. I suggest something similar or greater than that. Remember that my panels will generate 160w when clean, at mid day, on the equator! If a bit dirty on a partially cloudy day up here at 52 degrees north in late afternoon in September you'll be getting a fraction of that.
Things you need:
Really thick cable: Don't be fooled by saying "oh, it is 10 amps, so this 2-core mains cable will be sufficient". The amperage rating of cable is to ensure the cable does not get so hot at the rated amperage that it starts a fire. But mains cable is thin enough that it will cause a resistive loss, even if not so much that it gets the cable hot. And you cannot afford to squander your hard won solar power on inefficient cables. Proper solar panel cable looks closer to starter motor cable in diameter (OK, maybe not that thick but you know where I am going) - to minimise the resistive losses. And while you are at it, keep that cable run as short as you can. Double the length of cable and you are doubling the amount of power being lost through the cable.
You need a solar charge controller. Get an MPPT one. These eek the most power out of the panels, while the cheaper PWM controllers waste power because they cannot convert it due to their simpler electronics. I have a very good CTEK D250S DC to DC charger. It is an excellent piece of kit - one side connects to your truck (without needing a charge relay), a second side connects to the solar, and the output goes to your camper battery. It then optimises power coming from the truck alternator and solar and feeds it through a built-in multi-stage intelligent battery charger to your camper battery. If the truck isn't running it doesn't drain the truck battery. If the camper battery is full and it has spare solar it charges your truck battery from the solar . About £200, but worth it.
Isolator: Fit an isolator so you can disconnect the solar power to the solar controller, in case you need to do maintenance on the system during daylight.
Battery: If you can fit 2 batteries in parallel then perfect. Ideally a couple of hundred amp hours in total. Don't mix battery types, sizes or ages. Get at least a "leasure battery", but expect to have to replace every few years. Proper deep cycle batteries are expensive, as are AGM batteries, but can be discharged more deeply and more often.
Battery monitor: Without one of these you have no idea of how much charge remains in your battery. And if you don't know the state of charge you are in danger of either overestimating and running the battery below 50% charge and killing it (unless it is an expensive AGM or lithium), or underestimating and sitting in the dark even though you had plenty of battery power. You can buy a cheap battery monitor that just reads voltage (or just read the voltage using a voltmeter and work it out), but for those to work you need to turn off everything that is pulling out of or charging the battery. If it is daylight the solar will be pulling the battery voltage up and will therefore cause the battery to look fuller than it is; if you are running lights etc then they will be pulling the voltage down. A better bet is a device like the Victron monitor I use (about £100). It measures the amps going in and out of the battery, and once programmed with the battery size can keep a track of its state of charge. So whenever you look at the display you can see how much power is left and therefore if you need to ration your use of electricity. Knowledge is power
Consider what is using your battery power: Change any incandescent bulbs in the camper to LEDs. Avoid running stuff off inverters unless you have to. Consider if you need to charge camera / phone batteries now, or wait until the truck is running tomorrow. If you can do something using propane rather than electricity, use propane. But the big killer is compressor fridges. I like compressor fridges - they work like your fridge at home, get cold quickly, maintain a temperature even in the hottest climates and work even when parked at 30 degrees. But they draw a lot of current - maybe 6 or more amps when the compressor is running. A propane fridge, as traditionally used in caravans, lacks the above advantages, but won't drain your battery.
Steve.