John, thank you for this information. I was unclear about the alternator light. The OP and Temp sensors are clearly on/off affairs and should work fine with an LED lamp. As you point out, the charging light needs to be a bulb that can pass a bit of amperage. I'll plan to replace the charging light with a stock Yanmar bulb and socket, if needed. I haven't inspected it carefully yett as it works reliably.