I have just found the Lister engine I have been looking for that is a slow speed, 1000 rpm, 9hp, original English made, air cooled, but without a starter motor and a generator. It does however have the provision for the starter motor to be placed in a casing with the flywheel.
I have a 48V wind turbine/solar array connected to a larger 48V battery pack as well as a small 12V battery pack (for lighting and controlling relays) that may need to be charged during days of low wind/low sun, I am intending to using the diesel generator as a back up.
I need to convert the manual or hand crank start type diesel engine into an electric one. The engine should be started automatically by a voltage monitor, which upon sensing a low-voltage on the 48V battery pack, energize relay to run a starter motor.
The problem that I am facing is how to protect the starter motor from over-cranking, since this would be an auto start & without any human intervention. The relay can be timed for a period of 0-a few seconds but that may under-crank or over-crank the engine, resulting in either failure to start or damaging the starter motor.
I have been investigating into this issue and came across a number of mini-controllers that offer that functionality, but that required synchronization, which I feel is a risky business.
I have finally decided to use a PM 12V motor for cranking up the engine as well as charging the small 12V pack. The PM DC motor would be always coupled to the engine by means of a timing belt and when the Voltage Monitor energizes the relay, the DC motor acts as a motor to turn the engine for 10 seconds, allowing ample time for the engine to start, and after that when the relay is de-energized, the PM DC motor turns into a Generator and starts to charge the 12V batteries, along with the 48V generator.
I am looking for a circuit or a ready made controller that could do the motor to generator conversion once the VM has de-energized the starter relay.
I would further appreciate any other possibilities to achieve the above with minimal hassle. Any input would be appreciated.
Thanks, Usman.