turtle with a set up like yours what all can you run in a decent amount of time? Can you run a space heater off that all night? Or maybe a tv ? Just wondering how it would compare to a generator if it would be worth it when the time comes for me to step up to buy one or the other.
No, you cannot run a space heater for even 8 hours off of a battery bank, unless the battery bank is just stupid huge. A 1500 Watt space heater will draw 12.5 amps, but that's 120-volts AC current, not 12-volts DC current as via an inverter. When using that through an inverter, since 120 volts divided by 12 volts is 10, then the 12.5 amps becomes 125 amps, plus another 10% that gets lost in the inversion process, for a total of 137.5 amps that get removed from the battery. Times 8 hours and it's 1100 amp hours, and since you don't want to ever draw the batteries down below 50% DoD (Depth of Discharge) then you're looking at a 2200 amp hour battery bank and about 1200 pounds of batteries.
Here's a similar discussion regarding the rooftop RV air conditioners that applies to heaters, as well.
http://www.expeditersonline.com/forum/truck-talk/30729-battery-powered-c-2.html#post404859
Without question, the most efficient and cost effective way to keep warm in a van or truck is with an Espar heater. There are other ways, but none are as efficient nor as cheap in the long run.
Ideally, you'd want a generator and a battery bank, along with an Espar heater, with the generator being used for air conditioning and for recharging the battery bank at the times when the vehicle's alternator wouldn't be charging them. But which way you go really depends on your amp hour requirements, i.e., what all do you want to run, and for how long, between fully recharging the batteries.
From my batteries I run the Espar heater, a Fan-Tastic roof vent fan, a laptop computer with 2 external WD Passport hard drives and external powered USB hubs, a printer/scanner/copier, a flat screen TV, a satellite TV tuner DVR receiver, a small AA/AAA rechargable battery charger, five florescent lights (one 12 Watt and four 8 Watt, rarely is more than one on at a time, tho), a three-speed desktop fan that I run sometimes in the summer, and the big one - the Microfridge refrigerator/freezer/microwave.
The satellite receiver is an amp hog, even when turned off. It draws about 5 amps on or off, so I have it plugged into a remote power cord where I can flip a switch and completely kill the power to it when I'm not watching it. The TV draws nothing when turned off.
The Espar heater draws as many as 8 or 9 amps when first starting up, but that only lasts a few minutes, and over the course of a 12 hour run time it draws an average of about 2 amps per hour, so it can be run off the cheap 12-volt Walmart marine batteries with no problem.
The Fan-Tastic roof vent fan draws 1.8 amps on low fan speed, 2.2 on medium, and 3 amps on high speed. The laptop doesn't draw much, even with the external hard drives, maybe 3-5 amps max.
So you can see, while the amps can and do add up, if you don't have a satellite TV and the frost-free freezer/fridge/microwave, and still had everything else I've listed, you can get by with two of the Walmart Everstart Marine Max batteries, although Trojan golf cart batteries would be way better.
But the
MicroFridge® Combination Appliance: Model 2.9MF-7TP Microfridge has a normal operating current of about .9 to 1.0 amps AC (which is 10 amps DC from the battery) when running, and .8 amps AC (8 amps DC) when in defrost mode. It is sometimes in defrost mode at the same time the other 10 amps are being drawn, so it sometimes draws 18 amps or so. Most refrigerators (in a home) will only run about 8 hours a day overall, and the rest of the time it sits there and just stays cold, depending on how often you open the door. In the van, the fridge runs about 16 hours a day, because in the summer it's naturally hotter, and in the winter the Espar heater is blowing right at the fridge (no real way around that in my particular setup).
When the microwave is running, the Microfidge is specifically designed to shut down so as to not draw more than 11-15 amps AC. It's a small, low power microwave (700 Watts), which means a lower amp draw, but for quite a but longer. If it says 4 minutes on the package, as with a full-power microwave at home, it ends up being 8 or 10 minutes on my microwave. The cooking power isn't the same as the Wattage draw, of course, and the microwave draws 10.9 amps on startup (110 amps DC), or 1300 Watts, but will settle down quickly to about a 700 Watt draw, or about 58 amps. For 8 or 10 minutes, that's hard on a battery, really hard on a hybrid marine or truck battery, and devastating to a normal cranking battery. A regular full-power microwave will draw about twice as many amps, but for half the time. High amp draws are for true deep cycle batteries, not the hybrid kind.
But overall, including the fridge, I average about 11.5 amps per hour over the course of a 24 hour day, sometimes as low as 4 or 5 amps, sometimes as many as 20 amps (not including the microwave). It's a hard row to hoe for a battery bank.
In my case, that's about 275 amp hours per 24 hours (actually, with the Peukert Effect or a battery bank this large and that amp draw, 11.5 amps is really more like 9 amps, so the amps drawn from the battery in 24 hours is actually 216 amps). With a 610 amp hour battery bank, and a 50% DoD, that means I'll have 305 amp hours available for 24 hours without having to recharge before I get to the 50% level. If I unplug the fridge for an extended period of time, then I could go more than 100 hours before I got down to %50 DoD.
So those without any high amp requirements, a couple of golf cart batteries, like the T-145's, would be perfect. They would run everything I've stated above, except for the fridge, but you could also run a microwave once in a while, and use one of those electronic Igloo coolers that draw about 5 amps DC.
