At first, we should know two facts.1. It is well known that the greatest problem of LED illumination is to keep the balance between the power and heat dissipation. The major LED power will be translated into luminous energy, but little LED power will be translated into heat. Because the brightness of LED is proportional to its forward current, the larger the current, the brighter the LED and the more heat it produces. The accumulated heat will shorten the life of LED, speed up the light decay of LED, and even burn out the LED.
2. Most LED will give rated current, for example, 1W for 350mA. But this does not mean that LED can only work on these rated currents, and the LED is not a constant-current device. For example, the 1W LED and 2W LED of Samsung are the same model, the current is increased from 350mA to 700mA, and the power is increased from 1W to 2W, so the LED can work anywhere between 350mA - 700mA.
Second, the volt ampere characteristic of LED will be influenced by the temperature. And the constant current LED bar works more stably and durably than the constant voltage LED bar.
Many people think that the LED voltage is fixed and the current is fixed too. In fact, the volt ampere characteristic of LED is not fixed, but varies with the temperature. So the voltage is fixed, the current is not constant and varies with the temperature. And its temperature effect (an increase in current caused by temperature rise) will be expanded by many times.
The following figure shows this temperature effect under constant voltage. When the temperature increases from 25℃ to 85℃, its current increases from 700mA to 1295mA steeply. So the heat will increase in a geometric ratio, especially when LED is working long hours. Its heat dissipation device will be overwhelmed and damage LED finally. The constant current LED bar just avoids this temperature effect, and always keep the constant current. Its heat dissipation device will work properly as expected.
At last, the constant current LED bar has high energy efficiency. Because a huge advertising billboard works every day. The saving cost per hour is small, but in one year, the saving cost will be considerable.
