Too many volts from a bike generator

I took a treadmill motor and hooked it up to an excersize bike in order to charge a 12v battery and power an audio system.  Unfortunately, it worked far better than I ever hoped and is pumping out 75v at a max pedal, 45v on an easy ride.  I've looked into various charge controllers, but they only charge batteries close to the input voltage, and step-down voltage changers take it directly down to 12v, too low to charge a 12v battery.  Any suggestions?  Thanks.

Toga_Dan5 years ago
If you mount a v-meter to handlebars, you can slow down if v is too high.

But a v-regulator is probably better.
panne5 years ago
the motor will put out higher volts without a load/battery. if you connect it to a large enough 12vdc battery, the voltage will be regulated by the battery.

it will be much harder to pedal with the load on so install a switch in the line so you can start pedaling, then switch it on. when your attached voltmeter reads 14.2 vdc while pedaling your 12 vdc battery should be fully charged.

if at anytime the voltage goes over 14.2 volts you are starting to damage your battery. this happens a lot with smaller motorcycle and lawn and garden batteries. be sure to switch it off while you are pedaling to prevent the battery from running the motor.

a charge controller or inline voltage limiter would work well to limit the voltage, but it also will limit the output in a way that you'll have to pedal much longer to achieve that same amount of charge level.
Qcks5 years ago
Mmmm.... I'm not as skilled at figuring out electrical schematics, but if you take the output, and split it into 7 paths, maybe put a 12 volt capacitor on each path, that should actually do what you want.
You'll probably want a shut off that kicks in after you stop petalling and the capacitors discharge.

I don't know how to draw that, but that's probably the best explanation i can give.
caitlinsdad5 years ago
I think you need to search for voltage and current regulators, something that smooths out the fluctuations and spikes in power and voltage. Good luck.