The two biggest power draw items will be recharging the laptops, and powering the fridge. The Draws of LED lights, I pod chargers/ cell phone chargers is pretty minimal. My laptop while watching a DVD will draw over 7 amps. That is almost 3 times as much as my fridge takes when the compressor is running, and it only runs 20 minutes an hour. With my Laptop off, but charging the battery, it takes about as much energy as the fridge's compressor( 2.7 amps)
The ARB is efficient, but teenagers are not. Keeping it in a hot Van in the desert will increase it's power consumption. The more it is opened, or cold beer replaced with warm, the more it will use.
While it is difficult to be sitting in the desert and not take advantage of the suns energy to charge the batteries, I believe, since you only have 2 weeks or so before leaving, you should just concentrate on getting the AGM batteries mounted, and properly isolated, and wired to the alternator for the fastest alternator recharging possible.
That being said, alternators do a pretty poor job in bringing the batteries to full charge. It varies by vehicle, but usually when the batteries are above 80%, the alternator only makes enough amperage to keep the voltage regulator happy. This means going from 80 to 100% can take several hours of driving. AGM batteries can be recharged faster than flooded batteries, but once the vehicles voltage regulator sees 14.4 or 14.7 volts, the amps taper way down to a level just high enough to hold 14.7. This can be as low as 8 amps, when the batteries are still 60 amp hours from full.
Idling the engine to charge the batteries is pretty wasteful as most alternators need higher RPM to make around half their rated amperage, and the hotter an alternator gets, the less it is capable of producing, and the more it produces, the hotter it gets. When my engine is hot, and my batteries are still 35 to 40 amp hours from full, I'm lucky to see 12 amps flowing into the batteries. When they are within 20 amp hours, I'm lucky to see 8 amps.
Again Vehicle specific, but Once 14.7 is reached, the amps get limited.
If you really want
solar for this trip, I'd look into at least a 135 watt Kyocera panel, and either hard mount it to the luggage rack, or have a method of storing it while driving. Being able to tilt it to the winter sun makes a huge difference this time of year. I have 130 watts on my roof here in Northcounty SD and am only getting 30 amp hours a day or so, but in the summer will get about 62 amp hours, and more when I tilt it.
Then there is the issue of wiring it to a MPPT or PWM charge controller keeping in mind shorter fatter cables over minimal connections will more efficiently transfer the suns energy to your batteries.
While even a little
solar is good to offset your usage, to keep the batteries happiest, they should really get 5-13 percent of their rated capacity, so 5 amps per 100 amp hours of battery minimum if you really want the batteries to last and perform. My 130 watt panel, if tilted to the winter sun is good for 7.3 amps. The MPPT controller might add an amp to this in cooler weather.
Also consider bringing a high amperage charger like
http://www.amazon.com/Black-Decker-V...012854-2785326 and extension cord for those times when you have access to the grid. Before I had
Solar, when I'd drive into the nearest baja town, I'd stop over at a friend's Casa with some lunch, and put 50 or 60 amps back into the batteries in a few hours.
That link has been varying in price by 50$ lately.
Good Luck, and have fun South of the Border. Hopefully you will not have to hide in the van often to avoid the occasional sandblasting afternoon windstorm. But if you do, you can amuse yourselves by watching those miserable few who only have tents.
Recommendations on solar setup
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Originally Posted by AxeAngel
