I planned on powering the TV, lights and possibly computer off a small inverter. I know the POS Onan generator in the Class C wasn't smooth enough to power my desktop computer. Every time it surged slightly, the computer shut down.
You're not going to get away with a "small" inverter if you want to do all that. Be thinking 1000watts continuous or more depending on what kind of lighting you're talking about. You're better off running dc lights off your house battery bank (isolated via diode from bus batteries hopefully so you can always still start the bus) directly. Get some LED lighting, in many cases there are direct replacements for bulbs that fit the fixtures you probably already have in your bus, and you can run them damn near forever off a couple deep cycle batts.
The onan generator isn't a POS persay (maybe it is, idk) its just not designed to produce a pure sine wave that electronics usually require. When you're charging a laptop off 110v, most of that "dirty power" is hidden by the 110vac to ~14-18vdc step-down and the fact you're charging a battery not providing power directly to the cpu. If you want to power a conventional desktop cpu, you'll want a dc-to-dc power supply as they're more efficient than stepping up from 12vdc to 110vac then back to 5-12vdc. Check out mp3car.com for more info on dc to dc power supplies (as someone suggested above.) If you'd like to run whatever you want off your genset, you can run whats called a power conditioner. This will smooth out the irregularities in the power being generated. A standard computer ups will also do this to a degree.
Laptops I have seen usually charge the batteries from about +18 volts DC out of the charger, and would need a DC-DC step-up converter to run them on mobile DC. Getting a small (~100 watt) Radio Shack or similar inverter to power the AC charger is usually simpler and cheaper. Just turn off/unplug the inverter when not in use.
You may have different experience, but I've yet to see a single laptop which would run off a 100 watt inverter. You'd typically need something in the 250-400 watt range. Make sure you test it out first or keep your receipt. You could do the math but these things are plagued by inefficiency and false claims, so ymmv.
Providing the -12 volts for a desktop is the toughest, as you would need a DC-DC converter, and cannot just regulate down the positive battery voltage. But I think the -12 volts was only used in old serial and maybe parallel ports, where the digital ones and zeros were sent as plus and minus instead of on and off. A 9-volt transistor radio battery might be enough to supply the reverse polarity if you needed that for a port. The new USB ports have 5-volt power, but I don't know the signal voltages. I would suspect a desktop would run just fine on the +5 and/or the +3.3 volts, or maybe that plus the +12.
Wait what? -12? Negative voltage doesn't exist, its just shorthand for saying the polarity is reversed. In a DC system you have positive direct current and ground. That's it. Ones and zeros have always been ones and zeros. They're either on or off, electrically speaking. Polarity only relates to how the wires are hooked up, and most modern electronics feature biased polarity, meaning they'll figure it out for themselves and either not work at all until you correct it or work just fine.
Building step-down regulators to run a desktop off of 12 volts is somewhere way, way down my list of theoretical projects for when I get a "round tuit." But if I get to it at all, I will likely only get as far as converting an ancient IBM Thinkpad laptop with a failing display that sits in my junk box. I would use it as a CPU with external monitor, as I know from experience that 12 volts to the battery clips will run one of these units. I can get an
adapter that uses a camera memory chip to replace the ancient hard drive for storage.
dc-to-dc power supplies already exist, and are designed specifically for the problems that vehicle computers face, namely remote switching by a key/aux switch, surviving low current states during cranking the starter and dealing with highly volatile power fluxuations. No sense reinventing the wheel when its been done elegantly already.
This howto is definitely in need of some construction
Maybe I'll work on something later when I'm a little more solid on my pv knowledge.
