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Ice Cream Cart/Electric Bicycle/With Generator

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rokyen

Posts: 3

Joined: Sun Jan 30, 2011 10:05 am

Post Tue Jun 28, 2011 9:01 am

Ice Cream Cart/Electric Bicycle/With Generator

So this may seem kind of goofy, and maybe I don't have the best plan here, but I'm wanting to build a small cargo trailer (to go behind the bicycle) to sell ice cream from.

Basically something like this guy except with a freezer and a compartment for the generator: http://www.utilitycycling.org/wp-content/uploads/Wandertec-Bongo-Bike-Cargo-Trailer-Large3-700x380.jpg

I'm probably going to use a small 1000w generator like this: http://www.hondapowerequipment.com/products/modeldetail.aspx?page=modeldetail&section=P2GG&modelname=EU1000i&modelid=EU1000IKN to power the freezer.

So I was thinking, what if I used my generator as a source of power for my electric motor as well? I wouldn't be going very fast, it would just be to assist me in scooting around town. Generally speaking, I'd just be pedaling myself.

Is this possible with one of your kits? Do you think the generator could handle a small freezer (5.0 cu ft.) and the motor? If I could get to my location fast enough, I wouldn't need to operate the freezer at the same time I'm using the motor (although I'd like to be able to).

Thanks!
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Oakwright

Posts: 104

Joined: Fri Sep 03, 2010 8:51 am

Post Tue Jun 28, 2011 1:51 pm

Re: Ice Cream Cart/Electric Bicycle/With Generator

Possible, yes. The best option, possibly not.

The thing is that the motor requires 36v DC, and the generator is putting out 120v AC. You can get a AC-DC converter, and step it down to 36v, but that will add an extra component, and thus extra weight. It will also complicate the wiring. (although it looks like that particular model can also do 12v DC, but that would still require something to step it up to 36v).

Also it is important to remember that the electricity coming out of a wall outlet is MUCH more efficient than the output of a generator. The cost of gas compared to the cost of electricity is substantially different.

IMHO, you would be better off getting a battery pack (SLA or Lithium) and charging it off of a wall. Carry a charger with you, and if in a pinch you can plug the charger into the generator and convert some gas power into battery power.

As for carrying the generator with you for the freezer... It depends on the freezer. That thing is rated at a max of 120v at 1000w... seems a tad low to me. As it says on it, it's meant for fans, lights, small power tools. Freezers take quite a bit of juice since they usually have a pretty beefy compressor. If you have a particular freezer in mind you should be able to compare to make sure it's sufficient.

Also be aware of all the PITA rules involving food service. If it's a "just for fun" thing, then no worries, but if it's going to be an actual business, then you have a lot of requirements about temperature of the ice cream, having water available to wash hands and scoops, stuff like that (which might mean you have to haul water if there isn't water available at the location). But if it's just for fun, then probably not a big deal.

I think it's an awesome idea.

I actually thought about building an electric xtracycle that makes espresso coffee. I didn't think of using a generator, and was trying to figure out how to power it off of batteries and solar. I rambled about it on my blog actually: http://blog.oakwright.org/post/52819292 ... le-barista

Check out the thread where some folks piped in their thoughts when I was exploring the idea. There might be something useful in there for you: viewtopic.php?f=3&t=1280

I totally think you should explore this idea, and if you pull it off, I totally want to see pics!
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digloo

Posts: 194

Joined: Sat Jun 11, 2011 2:15 pm

Post Tue Jun 28, 2011 2:10 pm

Re: Ice Cream Cart/Electric Bicycle/With Generator

you'd need a generator that can handle the max power needs of the entire cart.

While you say that the freezer needs 1000 W, remember that the motor needs 750 W. That's nearly 2KW.

That generator only puts out 8A at 12VDC. At 36VDC, it would be equivalent to 8/3 or 2.6A. A 750W motor at 36V takes 20A. That's not nearly enough juice for the motor.

However, the duty cycle on the motor is probably very low, and isn't well-matched for your needs.

What's wrong with using a battery for the motor on the bike? You can pedal some of the time, and use the motor for assist. Most of the time you'll be standing still or moving fairly slowly, right?

Just some thoughts.
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admin

User avatar

Site Admin

Posts: 432

Joined: Sat Aug 30, 2008 11:23 am

Post Wed Jun 29, 2011 9:38 am

Re: Ice Cream Cart/Electric Bicycle/With Generator

ZACH?

I have a brother in law doing the same thing.
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lfairban

Posts: 124

Joined: Tue Oct 21, 2008 10:21 pm

Post Wed Jun 29, 2011 2:37 pm

Re: Ice Cream Cart/Electric Bicycle/With Generator

Overall, I agree that using a tube battery or another 36 V ~10Ah battery and taking the charger if you think you might need it, is probably the best simplest solution.

I thought of something else that might be a tad more efficient if you really want a serial/parallel tri-bred power source. I hesitate to mention this because it advocates purchase of an off-site battery, but:

Based on the assumption that the generator is actually a 12V generator with an on-board inverter to supply the 120V AC outlet, you might be better off bypassing the inverter with a battery charger designed to charge from a car battery. RC hobbyists use these a lot with lithium batteries that do not have the BMS built into the pack, it is in the charger. You would need 2 18V packs, and two questions come to mind. Can you charge them both without disconnecting? I think so. Can you charge them and use them at the same time? I am not sure about this one. The reason they can charge an 18V pack from a 12V source is because they are charging the 3.7V cells individually.

If you can't charge and use simultaneously, you could ride assisted 5-10 miles as they are 5 Ah max., then start the generator, chill the contents of the cooler and charge the batteries for the return trip. It might depend on how long you have available to charge them.

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