When running off the battery, the LEDs required a little under 30 percent of the current required by their halogen counterparts. When hooked up to our constant power supply, they drew about a quarter of the current. In either case, we’re talking about a substantial increase in efficiency and savings.
Running the entire halogen lighting plan for just two hours, for example, would discharge 37.26 AH (2 hours X 18.63 amps) from the boat’s house bank. Those same two hours would discharge just 11.90 AH when using LEDs. With the 25.36AH you save, you could run a refrigerator for half a day. And remember, this is for a conservative lighting plan. It also doesn’t include any other light usage after the sun goes down.
Let’s say some of the crew stays up late on a rainy night swapping yarns in the saloon. Two additional hours of one-upping each other over rum drinks will add another 30.98AH to the daily load with a set of halogen bulbs in the saloon, while LEDs will consume just 9.58AH. Now the total lighting difference for the evening is 46.76AH—and we still haven’t included things like courtesy lights, cabin lights or reading lights after the crew’s less garrulous members retire to their quarters.
In terms of dollars and cents, it’s next to impossible to quantify the differences given all the variables involved. These include everything from battery cost to fuel cost, alternator efficiency, the cost differential of the lights themselves and the difference in ownership costs of the lights given the longevity of LEDs.
Nonetheless, the switch to LEDs might easily allow you to get by with a slightly smaller house bank. You might also be able to add an additional piece of equipment without upping your total power usage or putting more strain on your house bank, thereby prolonging its life.
Never forget that a battery’s rated amp-hour capacity is far greater than the number of amp hours it can actually provide. Because of the inefficiencies inherent in traditional battery technology (modern lithium-ion batteries behave considerably differently) a 50AH difference in energy usage is roughly equivalent to 100AH or more in battery capacity.
Equally important, if not more so, is the impact this savings will have on generator or alternator running time. Again, lots of variables are involved, but aboard a typical 35-footer, like the one in this test, the difference could be an hour of engine running time per day on passage or at anchor. Now the decision to switch to LEDs becomes a quality-of-life issue. No matter what the cost of fuel, nobody likes running their auxiliary for the purpose of topping off the batteries. In terms of peace and quiet alone, this simple study shows LEDs are worth the trouble and expense.