I disagree. I don't think it's insane at all. Inverter gens go AC->DC->AC and people swoon over those gens' "efficiency". When the truth is, they aren't efficient.
So it's a matter of perceptions vs. reality. Perceptions wins.
Efficiency is a Holy Grail. To me it makes sense to chase down that last percentage point of efficiency for a fixed base operation like a house or utility grade solar installation.
But a vehicle? Puh-leeze. Doesn't much matter. There ain't nuthin' efficient about the solar, alternator, generator or anything else about a vehicle/boat/RV electrical system to begin with. How many hours the truck gets driven is more important.
And look at what we're talking about here - storage of electricity anywhere from 3,300 watt*hours up to 20kwh.
A few wasted watts here and there isn't important. What IS important is trying to fill up that electrical black hole.
Solar? 1kw of solar vs. 20kw of battery? Do the math. And that's assuming the truck has enough room to install a solar array *capable* of producing 1kw when hot. Prolly need 1.3kw or more of PV modules installed. MORE if they don't tilt & track.
25a 12v-48v converter? 20,000w ÷ 48v = >400a. 16 hours drive time. At least. 16 hours non-stop 100a load on a 12v alternator? Good luck with that.
Generator? Say a 3kva genset. Supplies maybe 30a @ 120v. 300a @ 12v. 75a @ 48v. 75a x 48v = 3,600w. 20,000 ÷ 3,600 = 5.5 hours.
So okay, we can forget solar. Can pretty much forget the alternator. We're going to need a 3kva generator (minimum).
Gotta run a 3,000w generator - at full load - for over 5 hours to recharge.
So why worry about AC-DC-AC conversion efficiency? It's a complete non-issue.
Hi dwh. I think you're spot on. However... none of it matters because the future is not solar, generators, alternators or anything else. The future is simply LOTS of battery power and charging it from what will eventually be a supercharger on every single street corner of the entire country.
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Just look at how dense batteries have gotten. The LG Chem RESU one's above have a useable capacity of 8.8kWh and weigh 165#. That works out to
53 watts per pound. Technology is going to rapidly increase however, and it is very possible that 10 years from now, that density will be doubled. So let's just assume for fun sakes that they do double it, and 10 years from now, you've got 103 watts per pound.
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Assume 1000# of batteries in a expedition camper. That may sound like a lot, HOWEVER, that camper no longer has any of the following.
No more: Solar panels, generator, AGM batteries, propane tanks (full), or heavy propane appliances (replaced with lighter electric). This would easily save a lot of weight. It's not uncommon for some campers out there, like earthroamer, to have (4) 255ah AGM batteries, which weigh 700# alone.
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Now those 1000# of batteries would put out 106kWh of power. And that power bank could be charged in about 45 minutes using a supercharger to 80%, or a bit longer to 100% (the Tesla superchargers put out 120kW).
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A 12,000 BTU air conditioner running 24/7 would only use about 12kW a day of power. Even with other electrical loads, the above camper could stay off grid for almost a week.
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Not to mention, solar panel technology WILL improve and one could still add solar panels to their rig if they wanted (probably makes sense).
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Even if you cut the weight in half, at only 500# of batteries, you still have 53kWh.
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Basically, in summary,
the days of generators, lead acid batteries and propane in RV's are numbered (and potentially solar panels if their efficiency cant keep up). In 20 years, finding a propane RV stove will be as difficult as it is to find a VCR today. Mark my words.
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But the future is basically here now. Even with today's densities, it is still possible to hit 53kWh with 1000# of batteries.
