Range-extender Sidecar for EV motorcycle

[Ryland]

I would worry more about your charger then your controller, if you try to drive and charge at the same time, but either way I think it will all be fine, you have the battery pack as the buffer.
If you are talking about a pusher trailer... then I would not do that with the motorcycle, to unstable! yes, it could be done, I'm sure but there are alot of things that could go wrong as well.
I have also thought about making a simple battery trailer with extra batteries, this would work for any electric vehicle and make the electric motorcycle alot more fun for short trips as you could leave it home and have the cycle be lighter weight, or make a really small light weigh electric motorcycle, or moped even and have all your batteries in the trailer.

[mattW]

Ben, I have been thinking the exact same thing for when I finish my bike. Check out renewable energy shops, there are generators made to directly charge DC batteries at different voltages for when solar/wind powered systems aren't putting in enough juice. I can't remember if you are running 36 or 48V but there are definitely options out there... here is a 48V 60A Australian option I was looking at. It would cost more than my entire build but i'm sure there are other (cheaper) options too. It would make for the perfect range extended EV without having to carry the extra weight when its not needed.

[mattW]

Here's another one for half the price. This could just connect in parallel with the batteries, when put under load (>60A) by the controller the voltage would sag until the batteries started putting in amps to the controller too (up hills etc). When the running load was <60 amps some of the excess power would go into recharging the batteries again. Going to mains voltage AC then back to DC in the charger would be fairly inefficient and you wouldn't get anywhere near the 60A that these DC generators can put out unless you had a super beefy charger.

[MazdaMatt]

Do DC generators generate DC, or do they generate AC and convert to DC?

Ben... What's your goal? Cross country trip? Or cross county trip?

[bennelson]

Right now, the motorcycle will go 30 miles on a charge, IF I drive 25 mph.

One client I work for a lot is 28 miles away. I would like to get there and back on a battery charge and a little fuel. Charging while there may/may not be available.

Even if charging were available, my current charger is VERY SLOW, and I am not interested in purchasing a more expensive charger, when there are still too many places I wouldn't be able to plug it in anyways.

If I were able to do 60 or 70 miles in a day (at maybe 35 or 45 mph) as a hybrid, that would be great!

[NiHaoMike]

Originally Posted by MazdaMatt

Do DC generators generate DC, or do they generate AC and convert to DC?

They generate AC and rectify it.

[MazdaMatt]

Maybe a battery trailer is your answer, then? You have 4 batteries @ 48 volts right now?

How high can you bring the voltage? I'm just thinking, if you can get 8 batteries on a trailer, you've got 72V in 2 strings. This will bump up your speed and your range and still allow you to do your "light" driving without the trailer.

From what I've seen, generators that are useful cost more than you're spent on your entire EV adventure.

[MazdaMatt]

Originally Posted by NiHaoMike

They generate AC and rectify it.

Then we might as well ignore DC generators. If a generator is the answer, use an AC generator and:
a) a transformer to up/down the voltage so that you can rectify it to a few volts above pack and add capacitors
b) rectify it, run it through a DC-DC that will give you a few volts above pack.

If charging the batteries is not going to happen, you can use a diode between the generator's massaged DC output and the battery pack. It will draw from the generator till it can't keep up, then draw from the batteries. When load is low, the generator will ease up.

[Ryland]

Originally Posted by MazdaMatt

Do DC generators generate DC, or do they generate AC and convert to DC?

Generators are almost always alternators and produce AC because they are more efficient even after rectifying it to DC.
If I was to build a trailer I would want something that would give me a 200 mile range as it would allow me to get to more car shows with my electric car and to larger cities that are around me, but my personal needs are around 10 miles per day.

[The Atomic Ass]

Originally Posted by bennelson

It seems that perhaps having a commercial generator with a 120AC outlet on it could have the battery charger connected directly to, and then the power of the carger goes to the batteries and motor.

I can't see that working unless you're drawing less than 2k watts at whatever your desired speed is.