I have a 1987 Suzuki DT6 2 cycle. It has a lighting coil with the leads to connect a rectifier to it to charge a 12 volt battery. The manual says that lights can be run just by using the lighting coil fixtures that will dump 12 volts and be able to power an 80w light bulb, but only while the engine is running. The manual advises to hook up a rectifier to charge a 12 volt battery and run the lights and acc off of that. Will this work to keep my onboard battery charged? Or is it not worth the trouble?

Depends on the output current on that particular engine. But as long as the voltage is regulated and it's rectified to D.C....it will help charge the battery. What you DONT want to do is hit that battery with 18V, if it's not regulated. But if the manual says it'll supply 12V, it MAY be regulated and just needs converting to D.C. via a rectifier...OR....they mean a combination rectifier and regulator which might be available.. Mike Halfmann would know. He'll show up here eventually.

Thanks, what the manual says is that the addidtion of a rectifier will charge the battery and all lights should be run off the battery but the rectifier will run a 12v 80w bulb while the engine is running.