RE: Field Charging
For those on a budget, I have to recommend the Harbor Freight 800/900 watt generator. No, it doesn't have an inverter, but for the majority of power supplies that's not a problem. I can charge two 5S 5000 packs at 10 amps with no problem. And that's really as fast as you need, if there is time in between your flights for someone else to get a flight or two. I'm pretty sure it would do 12 or 15 amps but the chargers I take to the field will only do 10.
Now, here are some lessons learned with my HF. I bought it in 2009 for the Nats, but I really didn't start using it a lot until about a year ago. At first, it could handle a good load. But it seemed to slowly lose the ability to charge at higher rates. Also, it would oscillate a lot. Well, I tried a number of things electrical, but it just continued to get worse. One day I decided to take it all apart. Keep in mind, the engine is just a 2-stroke, so it is really simple to disassemble. The first thing I found was the spark plug had corroded. About 1/2 of the tip was gone. So I got a replacement plug from an Ace Hardware store. Then I found the real culprit. The engine had so much carbon deposits on it that the exhaust port was almost fully closed over. You couldn't have stuck a pencil through the hole that was left. It was a simple job to remove the carbon build-up. On the head and the top of the piston I used a dremel wire wheel. Run the tool at about 1/2 speed and the carbon comes off easily. You may need 2 or 3 of the wheels to get everything done. On the exhaust port I just picked away with a x-acto knife being careful to not scratch the liner. On the side of the piston I used a knife to get the big deposits, then used some 800 paper to get the rest off. The rings come off the piston pretty easily, so take them out when you do the work. Make sure you put them back the same way, the top ring on top.
Also, the alternator had accumulated a lot of dust. I blew out as much as I could and it was quite a lot. When I had been using it it was in front of my van on our dirt parking lot. You may not have the same issue. But I am going to get a stool or a small table to get the generator off the ground.
There is also some adjustments that are not outlined in the manual. There is an adjustment screw on the side the fuel valve is on that adjusts the governor action. I found that adjusting this helped the engine to run steady. There is also an idle adjustment that can keep the engine from getting too slow when the load reduces.
With this maintenance it is now running like a champ. And seeing as how you can sometimes find these for sale at HF for $80, it's hard to argue with it. When I took it apart I was pretty impressed with the quality of the parts. The engine is not built cheaply, it is actually pretty good.
One other thing. Since I had a lot of it I was using Amsoil for the fuel mixture. I wasn't running it at 100 to 1, I was doing the recommended 50-1. So that may have been the cause of the excessive carbon build up. I am now using the amsoil at 100-1 so we'll see how that works.
It is not a super quiet generator like the Honda, so I have a 50-foot extension cord and I put it in front of my vehicle to block some. I've been thinking of making an after muffler just for grins to see how that would work. Heck, it's a 2-stroke! Maybe I'll make a tuned pipe! Who says I'm through with IC engines for pattern?
Hope this helps!