How to choose a good low-voltage led light bulbs

How to choose a good low-voltage led light bulbs

       At present, there are so many kinds of 12V/24V low-voltage bulbs in the market, and the prices are varied,take 9w for example,the price from 2.5RMB to 28RMB.But for same LED Why price is so difference more than 10 times? What are the main solutions for low voltage LED light bulbs?What are their strengths and weaknesses?How to choose a good bulb in so many choices?
      To do a better job, let's take a look at some of the most common low-voltage bulb .
  1.Constant voltage without power supply low voltage bulb

      This is the DC12V 9W bulb which saw from Facebook based on price 2.5RMB.I was shock when I saw it ,how to make it based on this low price ?Even we can’t buy the material under this price.But when we open it ,we found the reason.
       First of all,there is no driver on this bulb,DC12V power directly connect the PCB through clip wire.this kind bulb only can work under pure battery input ,cant be compatibility with AC input.Can’t work under any generator access, otherwise it is very easy to burn.
       Secondly,Let's analyze the lamp board.We can see it clearly in the picture.There are 12pcs SMD and 4 pcs 33Ωresistance,So the configuration its going to be 3 strings of 4.As each SMD voltage is 3.1-3.2v,3pcs SMD in series total voltage is 9.5v around, less DC12V input,So in each series have to add a resistor to reduce the voltage so that the bulb won’t burn.

  From above we can found some Some fatal flaws of this kind bulbs.
     ① No power supply,The external voltage cannot be converted to a stable current to be used by the light.As we know,LED light SMD need to work in a constant current state to avoid the problem of frequency flashing and brightness inequality, but this design is obviously not good.What's more, the low-voltage circumstances is not stable. The voltage in the battery is different from that full of power and loss.Take 12V battery for example ,when its full in electricity,some battery voltage can be up to 14.7v.Also the voltage will be be step down under using.Its will be under 11v when power is loss.How long do you think SMD life will last when the input voltage is so different?
     ② The series design of the resistance and the led SMD can play the role of partial pressure,But don't forget, the resistance also consumes power when it is reduced.Lets have a simple calculation,suppose this light is 0.5w for each SMD,the current is 150mA,then the wasting power of the resistance is :0.15×0.15×33=0.74W，you can see from that ,A resistor's power is higher than a lamp,also the whole light real power is:0.5×12+0.74×4=8.96W.But the power of SMD is 6w,in other world ,the light which marked 12w is almost the same lumen of ordinary 7w bulb light,and the whole light lumen efficiency wont be up to 60lm/w.
     ③ This light structure is extremely simple, without any heat dissipation design,Even worse is that 4 resistance is almost 3w the net calorific value of all focus on the light board, plus heat of SMD itself, its also unable to avoid to make it work in high temperature environment .The whole life of the lamp will not be too long.

 2. Low voltage constant current scheme

      This is the low-pressure bulb with power plan, and the performance difference of this kind of lamp is mainly reflected in the power plan selection.the most common is that AC/DC 12-85V wide voltage scheme,The programme itself has some of its own characteristics.
     Its biggest advantage is the compatibility with the external voltage, not easy to burn.As we know,The use range of low-voltage lamps is very wide, from 12V to 36V of the machine, from AC-DC, the environment is different, so the characteristics of compatibility are very important.
According to our detailed understanding and testing, this scheme can be compatible with AC 8-64v, DC 8-85v voltage.This ensures that the scheme will not be too much problem even when used in a relatively hostile environment.
     But this scheme also has some defects, from the actual test, this scheme under the condition of less than 25v input voltage, the power will reduce by the voltage change and will keep stable in more than 25 v power.

       We can see the effect of the voltage on the power of the whole lamp, and this is just the test of the integral sphere in the state of the dc input, if the outside input is ac, the power will be lower.

       The same 12V input, DC significantly brighter than AC, visual flux gap of 150 LM.From this point of view, the design plan is mainly designed for DC, the performance of AC is very limited.
        In addition to this wide - voltage scheme, there are some DC12-24v narrow voltage schemes in the market. This type of scheme is relatively stable and does not fluctuate too much with voltage fluctuation.However, the defects are also obvious, and the environment requirements for external use are relatively high. In some harsh environments, it is easy to see a large number of dead lamps.
        Of course,except above two type,There are many other options available on the market, and we'll explain them in detail when we test them.
        A low voltage LED bulb light in addition to the choice of scheme, as well as assembly material choice, which will be a large extent determined the price of the lamp. But its same principle to choose high voltage or total voltage solution light, Here is a different explanation, anyone interested can take a look:
       LED Luminous Efficiency
    Luminous Flux Of LED Lights
    There are many options for low voltage bulb light, but as long as we know the scheme and structure, we can choose the bulb light that can suit us.

Copyright by ELEGENT TECHNOLOGY.