Tiny gas generator

[bm_cricket]

Hi all!
I've decided that I'm going to apply for a DMV permit this year! I've done some math and I'm fairly sure everything will run fine. One tiny little issue with my plan is this: I need more power. I've got two 24v 13.2A (maximum draw under worst case work load) motors. I've got four 12v 86Ah AGM batteries. I believe the math works out so I have about 5 hours of worst case motor draw with a little buffer so I don't over drain the batteries. I'm not going to put more batteries on my art car.. those things already weigh close to 200 pounds!

Okay, the point is, I need a small generator. It's totally possible I can ride around all week and just charge when I get back to camp, but I don't want to rely on it. I want to put a small gas powered generator. Small and noisy is fine.. even under 1,000 watts would be fine. Does anyone have a suggestion on a generator? It's just so I can get back to camp if I wind up in deep playa with a dead battery! My motors will only run well enough to drive me around if they get 24v, so I'll probably need to do some funny step-up transformer business if the generator outputs as 12v, or maybe I'll go to 110v and then back down to 12v. Wacky stuff.

[maladroit]

If noise really isn't an issue, then I suppose a very crappy $100 2-stroke would work. But I hate to recommend that anyone buy those under any circumstances. You can get some cheap 800-1000 watt generators from Champion and Generac and other random brands; the key is that if it says "Inverter" in the name and HAS a decibel rating, it's probably going to be much much better than the crappiest of crappy Horror Fright generators. But you'll pay closer to $300.

There is a 1000W Honda EU, it's tiny and adorable and quiet. It's also not ultra cheap.

In fact, the smaller you go with generators, the worse the watts-per-dollar will be. You can see double the output power with a 25% increase in cost.

[Elderberry]

Don't forget, whatever the wattage rating of the generator is, it is at sea level. The wattage drops considerably with increased elevation and temperature.

Here are some points to keep in mind when calculating how much power your generator will support when running on the playa. Black Rock Desert is approximately 4,000 ft. above see level.

Altitude and Temperature
Altitude and temperature can have adverse effects on generator output. Let’s begin by looking at the effects of altitude. Gasoline powered generators will decrease by 3.5% in power for each 1,000 feet of elevation above sea level.

Example: A 6 KW generator in Black Rock City, NV
4,500 ft. elevation
3.5 x 4.5 =15.75% decrease
Maximum output is now 4,950 watts.

High temperatures can also decrease the efficiency of your generator by 1% for each 10° above 60° Fahrenheit.

Example: A 6 KW generator in Black Rock City, NV
It’s Labor Day weekend; the temperature is 120°
120° – 60° = 6 x 1 = 6% decrease
Maximum output is now 5,640 watts.

Now let’s see what happens when you combine high altitude and high temperature.

Example: 6 KW Generator in Black Rock City,NV
Elevation: 4,500 ft. elevation
Temperature: 100° Fahrenheit.
Altitude: 3.5% x 4.5 =15.75% decrease
100° – 60° = 4 x 1 = 4% decrease
Total decrease = 19.75%
Maximum output is 4,815 watts.

[Captain Goddammit]

The 12-volt battery charging outputs on most small generators are very low-power and would be a waste. You'll need to bring a real battery charger and just plug that into your generator.
All of this is kinda' silly, this is why gas engines are more practical Mutant Vehicle power in the first place.
Don't buy a little two-stroke unit, you'll really hate it. They are exceptionally loud and stinky too.

[Popeye]

Small 12 and 24V gas battery chargers are available. Suggest you use the same charging voltage as you are using to drive your MV. Makes recharging much easier.
https://www.google.com/search?q=gas+bat ... 8&oe=utf-8

OR

Build your own. An old lawn mower or snow thrower engine (I'll guess 5hp?) with preferably a horizontal shaft and an alternator, which will have a built in regulator and rectifier. A little expermentation and math to size the pullys, mount on a 2x8 or a piece of strut.
I'd probably talk to someone at your local starter and alternator rebuilding shop. Look in the yellow pages under "Auto Electric". Tell them what it is for and with any luck they might get interested. Something different relieves the boredom of any job
24V alternators are available.

[skippy3k]

But to your original question about a generator recommendation, obviously the Honda EU series are great. I owned a 2000 watt Honda and loved it. I now have a Champion 2000 watt and I gotta say....I love it too. I know Hondas are always the "go to" choice here, but if you are looking for a less expensive alternative, the Champion is a great product. The specs are practically identical to the Honda (although I think it's slightly louder...but not by much), and built very well. I also like the square shape of the Champion. It packs much better because I can stack things on top of it. (When it's not in use, of course.)

[bm_cricket]

Thanks everyone!!! I've thought about getting a little Honda EU1000 type generator because it would be "useful the rest of the year" but then I remembered I will never actually use it. I've got a EU3000 model and I only use it at Burning Man. Having a smaller one sounds great but for close to $1,000 I just don't think it will pay for itself. I genuinely think building something out of a rectified 24v alternator and a tiny gas motor will be the better option. I'll call the local small motor repair shop in town (they service generators and small tools) and ask what they think.

I'll be sure to check back in with results when I finally make a choice. I'm trying to accomplish this backup power source for under $300. Generators exist in that price range, but they are junk.... This 24v alternator thing sounds like a brilliant option.

[mdmf007]

a decent alternator from a junkyard can easily put out 90-120 amps, just look at the rating on the side as you dig through the yard. Couple that to a 3 or 4 hp 4 stroke motor and you can charge batteries easily. We have built these in the past fairly cheap. Used lawnmowers make good motors and are plentiful as well as dirt cheap. Horizontal shafts are easier to work, but an alternator could care less of its orientation. A larger engine can easily spin 2 or 3 alternators as well.

[Captain Goddammit]

Am I the only one who thinks it's... unnecessarily complicated to use a gas engine to drive a generator to run an electric motor? I mean, it works for ships and trains, but..

[bm_cricket]

Am I the only one who thinks it's... unnecessarily complicated to use a gas engine to drive a generator to run an electric motor? I mean, it works for ships and trains, but..

I don't want to listen to a gas engine all day. I think the batteries will last for at least 5 hours of driving and I think the charging will take another 8. The generator is for a last ditch effort to get back to camp if my batteries die. And the model of "all electric with a generator" works for the Chevy Volt. :-p

[maladroit]

Am I the only one who thinks it's... unnecessarily complicated to use a gas engine to drive a generator to run an electric motor? I mean, it works for ships and trains, but..

I don't want to listen to a gas engine all day. I think the batteries will last for at least 5 hours of driving and I think the charging will take another 8. The generator is for a last ditch effort to get back to camp if my batteries die. And the model of "all electric with a generator" works for the Chevy Volt. :-p

The Volt does have a clutched mechanical connection from the gas motor to the drive train, so the gas motor does on occasion put power directly to the wheels without an intermediate generator.

[Popeye]

Using the model of a 12V generator and a battery you could power most things generally used on the playa except an airconditioner.

[Captain Goddammit]

I've got a great idea. Why don't you use a generator to run some big floodlight, pointed at some solar panels to charge the batteries? Maybe those batteries could power a fan that blows at a windmill that turns the wheels...

[bm_cricket]

I've got a great idea. Why don't you use a generator to run some big floodlight, pointed at some solar panels to charge the batteries? Maybe those batteries could power a fan that blows at a windmill that turns the wheels...

Great idea! But is it sustainable? I don't do things that aren't sustainable. Is that idea gluten free? Soy free? Dairy free? GMO free? Does your idea meet my spiritual needs?

I know that having a gas engine on an electric car sounds ridiculous, but if I drive out to deep playa and suddenly find myself without enough battery remaining to get me home, why not have a backup plan?

[GreyCoyote]

I'm not up on the design of your MV layout, size or weight, but maybe this idea could work for you.

Since this is a "limp home" motif, how about making a small system, based upon a very small mower engine, that is coupled directly via a shaft-to-rim-drive arrangement to a small tire. The entire assembly mounts on a hinge and is held up out of contact with the ground during normal use. If you get caught without power, swing the power unit down so the tire makes contact and yank the starter. Throttle control could be via hand throttle. It could be used in either a pusher or puller config or even mount amidship under a seat or something.

This certainly isnt elegant, but it is simple and practical for a lightweight MV. Investment would be very small. If you are a bit of a fabricator, build time would be nearly nil as well.

Edited to add: ... And its gluten-free, spiritually acceptable, and hippie proof.

[GreyCoyote]

Hey: is this based on a golf cart frame?

[bm_cricket]

Hey: is this based on a golf cart frame?

It's all built on this thing: https://eplaya.burningman.org/viewtopic ... 1&start=30

[GreyCoyote]

Sweet!

Call me!

[trilobyte]

I think any pretense of being sustainable go right out the window when the electric vehicle is getting all its juice from gas-powered generators. Whether on-board or at camp, if the power source is fossil fuel then what you've basically got is something that's burning fossil fuels in order to get its energy. Further, due to the way energy conversion and storage works plus the additional energy requirements of hauling around the batteries, you're likely actually burning even more fossil fuels than you would if it was just a gas-powered vehicle making use of an alternator to provide on-board electrical needs (lighting, etc). It's also more expensive, and there are other considerations as well.

I totally see where the Captain is coming from, and if it were me I'd go with a gas-powered vehicle and just put some thought into a muffler or baffle if engine noise is a concern.

Your mileage may vary, of course, and in the end you're welcome to try whatever idea you want, no matter how crazy it may sound to any of us. Good luck with your project, whichever direction you choose to take it.

[maladroit]

That thing doesn't need a generator. If you're unfortunate enough to run out of juice, it's basically a bicycle. Push it home.

[GreyCoyote]

An epic little art car! Quite a history too. Regardless, backup power is entirely do-able.

If all else fails, you could always hitch-up a team of passing sparkle-ponies and just bump-draft the nearest party barge.

[Captain Goddammit]

Ha, just teasing you because it sounds a little Rube Goldberg-ish.

I'll tell you what I'd do: If you're concerned about getting stuck with dead batteries, just carry a spare get-home battery.
A gas on-board charging setup will be too heavy and add unnecessary complexity, expense, AND take way too long to get you going. You could just flip a switch and cruise home on your reserve battery. Then charge at home off your main charger.

[FIGJAM]

A single "Get home" battery is the best idea.

With your 24volt system you'll only go half fast to get back to camp, but it's the easiest.

[Meat Hunter]

What is a "Get Home" battery?

[mdmf007]

Am I the only one who thinks it's... unnecessarily complicated to use a gas engine to drive a generator to run an electric motor? I mean, it works for ships and trains, but..

Yeah my post was about charging batteries - if were actually moving something then your prime mover is gasoline. Whether you turn it into electricity to store in a battery for use later or turning an electric motor outright. Conversion inefficiencies being what they are your best to put the gasoline to work doing what gasoline does best and turn the wheels.

If your looking for "limp home power" which a couple hp of alternators is not to do for you. If that was my rig, and it was absolutely necessary to imp home. I would install a small hydraulic motor running off a small gasoline engine and pump - closed circuit as well. Of course I have a shit ton of tools, a lathe and a mill to make what i need. others pointed out that your losing a lot in converting energies.

good luck.

[Token]

Looking at that differential pic, looks like there is a sprocket on the rr wheel already.

Why not build a "passenger foot rest" that oddly resembles a twin-pedal shaft and have a clutch for stationary engagement.

A lot more reliable and can be gluten free.

I like Capn's suggestion of a smaller "Oh Shit" battery best.

[Elliot]

Wasn't that thing intended for pedal-power in the first place?

[bm_cricket]

Wasn't that thing intended for pedal-power in the first place?

It absolutely, 150% is intended for pedal power... But so far I've made no progress on the pedal power front.

[Zubeneschamali]

Grappling hook and wait for a bigger art car to drive by.

All soy baby - Gluten free is for chumps!

[Captain Goddammit]

It absolutely, 150% is intended for pedal power... But so far I've made no progress on the pedal power front.

Few of us pedal at 150%, so electric assist seems wise. Screw the pedals.