Thanks for pointing out that electric motor you have which has permanent magnets and I would then assume it has brushes which does mean it can be used as a generator. Good deal!
I have a fuel pump that runs 12 volts at 12 amps. It runs real smooth at supposed to be 1750 rpm. It was in the dumpster and the pump does not function, but the motor turns good.
I'll see if I would fix the pump or scavenge the motor out of it for something like what you are doing.
Since I have twin jack shafts, which means that at full throttle I could use one of the slower moving jack shafts to be attached to the motor used as a generator. This makes sure that it shall not be turning faster than safely acceptable. I did notice that the motor you have does 4200 rpm so you got a winner there!
I know you have a 12volt battery. What battery is it that you are using, type and ampere hour?
A voltage regulator circuit or one specifically for charging the battery may be something to use. In the simplest form you might on the cheap just dispense with a regulator and just use a high enough wattage rated resistor with an ohm value picked to limit the charge current to protect the battery.
I am in between jobs as an electronic technician, but my dad long ago showed me how to use a higher direct current voltage source safely to charge batteries with this method of just a single resistor.
It was cheap and crude, but effective. With a toy train transformer that out puts 18 VAC and a full wave bridge selenium rectifier to make a fairly smooth 14 VDC voltage, we put off buying a car battery charger.
There is an internal resistance in a battery and with the right resistor picked and put in series with the charger going to the battery you limit the current that charges protecting the battery.
We used a current meter in series that could handle the maximum current and measured the current charging the battery. Trying various resistors of high enough wattage rating, we found one that would give a charge current at about 10 percent of the ampere hour rating of the battery. It is sort of a safe rule of thumb. The small group U1 absorbed glass mat sealed lead acid battery I have is 12 volts 30 ampere hours, so I would limit to 3 ampere hours.
The toy train transformer and the rectifier I would figure could output around 20 amps at 12 volts DC which we would use to jump a battery to help start the car in the winter but not as a regular charge source.
MT
