Why Constant Current Control?

The State of Marine LED Technology Today:

LED's have just recently become suitable for replacing the incandescent light bulbs used for illumination on your boat. Technology is rapidly improving, not only in the light output, but also in output color. This is due, in some part, to improvements within the manufacturing process, but, the real gains for us boaters have been in the thermal management improvements and LED driver technologies that are being developed and incorporated into integrated circuits small enough to live withing the form-factor of a small LED bulb. The current efficacy benchmark for LED replacement bulbs in a warm white color is hovering around 50-70 lumens per watt. For each gain in light output, we create an even bigger thermal management issue. You see, the solution isn't necessarily making a brighter LED (that has been done), the problem is being able to give it a high driving current while keeping it cool, all without stepping over the boundries of the form factor of the bulb we are trying to replace. An interesting fact about LED lighting is that for every 10° C increase in junction temperature over its design threshold, the life of the LED is cut in half! Another way to say it is that you can give any LED a large amount of current, and it will be very bright for a very short time!

Why you don't want resistor controlled high-output bulbs:

We would venture to say that 99% of the products that we see that are being sold as "marine lighting" are being controlled by a simple ballast resistor. Resistor controlled high-output LED bulbs generally have no place on a boat. This is because current is used to drive LEDs (not voltage). The more current, the brighter the LED, and the brighter the LED, the hotter the LED junction gets. The hotter the junction, the shorter the life. A resistor is fine at controlling current at a specific voltage, so if you design it for 12V input, and your voltage doesn't vary in the slightest, then you should be fine. In other words, you should be be fine if you aren't on a boat or live in a world of big battery banks, variable charging devices (alternators, solar panels, wind-generators) and so forth.

Another interesting fact is that when controlling LEDs with a resistor sized for 12V, if the boat's voltage goes up 25%, say to 15V when charging, the current went up more like 30% because of the voltage drop inherent to the LED itself. You can say goodbye to an LED that has seen a 30% spike in current. To avoid this fate what most resistor bulb manufacturers do is to give themselves some headroom and to size the resistor for 14V, which is fine if it is to be used for a tail-light on little Jimmy's rice-burner, but when the voltage on the boat drops down to about 12 volts, the bulb is now 25% less-bright as it was at 15V.

To make matters worse, a resistor is painfully inefficient at its task because it controls the power by bleeding it off in the form of heat, and we are trying to avoid heat so that we can maximize brightness and LED life. We are also likely anchored in the tropics and want to stay cool. Eventually, every watt of power given to the bulb ends up as heat in the boat. Each 10 Watts equals about 1.7 BTU's per hour.

We have all heard the horror stories of the fellow boater who bought Chinese "tail light" LED bulbs on the internet or from that "ScamWOW" guy at a boat show only to have cold, clammy, blueish light for a short period of time before they gradually got dimmer and finally winked out. We here at marinebeam.com are weary of hearing these stories. This is why our focus is on selling current-controlled products using the latest Pulse-Width-Modulation DC/DC converter technology.

What is PWM DC/DC converter technology?:

Without getting too technical, it is the most power-efficient way to close-loop the current that the LEDs in each cluster see. To maximize brightness and ensure a long life, we want to drive the LED at its design forward-current regardless of input voltage, and we do not want to over-drive the LED whatsoever. The integrated circuit we employ in our constant-current products can provide this constant-current to the bulb from 10V - 30V. What this means is that the bulb is absolutely as bright at 10V as it is at 30V. For those with voltage drops to your fixtures, this feature adds another big benefit.

What are Surface Mount Device (SMD) LEDs?

SMD LEDs are flat LED chips which bond directly to a highly thermally-efficient aluminized substate (printed circuit board). Unlike traditional parallel leg through-hole type LEDs, they are not restricted by having to dissipate their heat through wire legs to the substrate. SMDs, in addition to being designed to be very thermally-efficient, transfer their heat directly to the substate over a wide surface area, and can be driven much harder. Therefore they are much brighter than traditional LEDs. They also are not contained within the plastic domed capsules like traditional LEDs, further improving their thermal efficiency. The SMD LED used in our high-output products generate half the junction temperature compared with their traditional LED counterparts, at the same current. Because they are brighter than traditional LEDs, we need fewer LEDs to generate the same light output. This is helping us make brighter clusters within the constraints of the form-factor we are trying to accomplish.

In Summary:

Constant-current drive technology is important when driving the latest high-power LEDs. It maximizes life, reduces heat, and and provides the brightest and most consistant light output possible. The latest SMD LEDs coupled with the constant-current drive topology allows marinebeam.com to offer the boating community a top quality product at an attractive price that we know you will be happy with.