I have the Sportsman generator listed earlier (got mine at Tractor Supply for $150 on sale) and have no problems with it. It is fairly quiet, but not as quiet as a Honda inverter model. I use it to run my 12V 20A power supply for field charging, as well as for my camper when I don't need to run the air conditioner. It also has a 10A 12V output (for
charging a 12v battery ONLY) that can be used to keep a deep cycle battery topped off. Don't try using this output to power your lipo charger, though, as it is unfiltered DC.
[link]http://www.tractorsupply.com/sportsman-trade-2000-watt-portable-gasoline-generator-4458506[/link]
You can't charge a deep cycle battery in 15min from you car alternator, or any other charge source for that matter. Not going to happen. It has to do with how fast the battery can accept a charge. At the very minimum it will take 4 hours to go from about 50% charge to 85% charge. (AGM batteries can charge faster than the common flooded wet-cell batteries). The last 15% charge may take 12-24 hours to accomplish. When I camp, I try to keep my 12v house battery between 50% and 80% charge. Going below 50% charge shortens the battery life.
I don't recommend using the car alternator to charge a depleted battery. Don't ask me how I know. [
] I know it sounds stupid, but the instructions that come with some (most?) alternators say they are not designed to charge a fully depleted battery. There are special alternators made for things like ambulance duty, but they are not common and are more expensive.
[link]http://econtent.autozone.com:24999/znetcs/psb/en_US/2/00/86/546-3tb.pdf[/link]
As to why non-inverter generators have noisy outputs, it has to do with how the voltage regulation is done. Some generators use a capacitor circuit to regulate voltage, others use an electronic AVR to do it. Both will have some distortion, but the electronic regulators generally have a cleaner waveform. I won't hesitate to use my Champion generator with my camper or to run anything. Most electronic power supplies are designed to handle distortion and transient surges (to a certain degree) without damage. The most likely way that a generator will damage electronics is if the generator's regulation circuit fails and drives the output high. The normal waveform distortion should not damage anything.
I have a WFCO converter in my camper, and I tried using one of the small inverter generators (ETQ) to run it. Did not work. The capacitor filter on the input drew too much current (inrush) when first connecting that it always tripped the output of the generator. I could use the ETQ to run my 12v 20A DC supply for my field chargers, but sometimes that would trip it as well. Once connected and running, it never tripped, it only ever tripped when first turning on the converter. I've never had that problem with my non-inverter generators. Other brand inverter generators may or may not have this problem.
Hope this helps.
Bob R.