The Gas/alternator powered E-bike

[TheE]

You might want to look in to something like this for power:

LM2575 - SIMPLE SWITCHER 1A Step-Down Voltage Regulator

Circuit is not too complicated, switching regulators won't need a heatsink the size of a birdhouse like 7812s.

 

[professor]

Thanks E but I think it is too complicated for me.
I brought a 7812 regulator to work and told the sparkeys what I wanted to do (charge battery with a couple of them) and they said it would blow in less than a minute ( other bugaboo was it was only good for 35 volts input), saying the battery would draw too much power. I am pretty good with mechanical things but these things are beyond me.
One of my buddies is going to see if he can find anything for me.
If you can think of something I can just attach (and not need other electronic gizmos attached to it) (and not cost an arm and leg) let me know .
I have come up with an alternative- use the stock remote alternator regulator but put in a 6 to 12 voltage reducer in the sensing line, thus fooling the regulator into jacking up the output to the field to double (hopefully) the alternator output to 24volts. Would have to set the engine at an rpm and leave it there, or have it run up with the e-motor.
And then run the bike off batterys with controller at 24v and the alternator just keeping the batterys at full voltage.

 

[professor]

I decided to see how the bike would do with the Techumseh 98cc on board. Even with 2 mufflers it is too noisy but worked well, I did silence the intake roar by attaching a plastic box with filter material in it and 2 snorkels leading to it- no sound coming from there that i can hear.
Has the same torque (power) as the HF 79. I had put on a 450 watt motor instead of the 250 and it doesn't accelerate any faster than the 250 watter I had before. Alternator is the limiting factor i guess.
The package is quite viable. It acts like a high stall torque converter below lock-up rpm, where you hit the gas and it goes but does not accelerate strong. As you get up to speed, you have to throttle back to almost idle to cruise.

At this point the bike will probably have the gas and alternator stuff removed because it is crazy heavy in the back- doesn't affect the handling while riding, but feels top heavy moving it around and the kickstand is overwhelmed.
But I learned a lot.
I would like to do the HF 79 / alt. in the frame of another bike (where it would make it fit). getting the weight down lower is a biggie. I love that HF engine. Strong and pretty quiet.