Oh, yes LEDs. Forgot about them. I replaced all the cabin lights (excepting the red/white ones), the running lights, and anchor light with LEDs. They use next to nothing for power, and run much cooler than the incandescents, which is important in Florida heat. I've not yet replaced the deck light as the bulb is only a year old.
I do monthly maintenance the first weekend of every month. Checking water levels in the batteries is on the list. The charger is always on with shore power in the slip. The two 4Ds were just fine. They were 3 and 4 years old, respectively. A week later, all the water had boiled out of them and the charger was trying to charge them up. I'm thinking I was lucky there wasn't a fire. After that, I wouldn't trust the OEM charger, so the computer charger was installed with the new batteries, including a temperature sensor.
I'm not a mechanic by any means. The information on this forum is invaluable.