My biggest concern with the generator in the back of the truck approach has been the sound. While perusing the internet today, I saw someone who built an enclosure for their generator, conveniently a Honda EU2200is (the quietest generator I looked at, and a potential option 3 in the last post). In their video, it was clearly a lot louder than the numbers lead you to believe. If someone is parked next to me, I don't want them to complain or call the cops or anything if my generator is running. So I ran some tests when I got home.
I tried to use the lawn tractor to do the measurements. But it didn't feel like cooperating. The battery was mostly dead.
Instead I used the pushmower. It started up unhappily.
At 8 large steps away (roughly 24 feet) the mower turned in 56dB. My curiosity peaked since the larger generators turned in that ballpark under low load, and the mid size generators turned in that range under full load. So I approached the mower to see what it measured as I approached it. Standing next to it turned in 65dB. This raises the question: would I be willing to run my pushmower in the back of the truck while parked?
To satisfy my curiosity, I also checked my truck. It measured a 48dB standing right next to the hood, and 40dB at ~25 feet (or on the other side of the car). So everything I looked at would be significantly louder than the truck. The smaller ones were 48-50dB at low consumption at ~25 feet.
Slightly confused by the numbers I was seeing, I also checked the example of talking being 60dB. That example is very misleading. It did measure 60 if the phone (my sensor) was 2 inches from my face and I talked directly into it. Even at just arm's reach though, it drops to low to mid 50s. A "typical" conversation is probably between 50 and 55dB if you are a participant.
After all the testing was complete, I decided to do something about the tractor since I probably ought to mow before I go down to KY for Memorial Weekend. So I put the charger on it and jumped it. It fired right up, and its numbers were comparable to the pushmower. Interestingly, at ~25 feet, the different between low throttle and high throttle was only a few dB. Sitting on the tractor, the difference is a lot larger though. It is good to go though, I left the charger on it for a few hours.
I also researched a few ways to make a generator more quiet (that was how I came across the video with the EU2200i). Some of them were pretty straightforward: put it in a sound absorbing box (make sure there is adequate ventilation!), put a car muffler on it (an interesting idea actually). Some were odd, like run the exhaust into a bucket of water. I looked at some of these ideas, and they do sell exhaust kits for the Honda EU3000is that bring out a pipe after the built-in muffler so you could in theory put an aftermarket muffler on it (or put it in water). If that is as effective as the internet claims (they claim a solid 10-20dB drop), I am a little surprised that nobody makes a generator with a car muffler on it given that noise is the number 1 complaint with generators. It might even be enough to make my current generator palatable.
One other option I briefly looked into was just putting a big-ass inverter on my truck. I was willing to run a bunch of power off the alternator as an additional charging source for the solar setup, why not just idle the truck (plenty quiet enough) and run a big-ass inverter? They make 2-2.5kW inverters I could hook directly into the battery circuit and mount under the hood. It wouldn't be hard to carry extra gas (my truck has a wimpy and tiny tank on it). Then I looked up the alternator, and the wuss of my truck extends beyond the tank. The OEM rebuilt alternator for my truck is only a measly 130A. That is sad. The Buick had that on it. The white truck with its V6 had that. The Dodge had a 160A on it. So drawing 2.5kW off the electrical system in the truck would be a very bad idea. Just out of curiosity, I wonder what the idling noise rating of a semi is, since that is where I would be parked, in the trailer section. Perhaps later today I will investigate.
Since I wouldn't be willing to run a lawn mower in the bed of the truck because of noise, I am left with only options 1 and 3. Either way, if I did go with a generator (as opposed to just putting a monster alternator and gas tank in the truck), It looks like a soundproof box will be required. They don't look complicated to build though. Adding a car muffler would likely drastically reduce the portability of the generator, so that option is out.
UPDATE - Adding a muffler actually looks really easy on the 7000, and Matt knows people from his work that use them for testing and say they are quieter than the numbers suggest, so I might dig a little bit more into it before I axe it.
Hmmm.
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