dc switching power supply question

[shawty1]

I have a led aquarium light that has a 12v 5a switching power supply,the problem i have is im on my third power supply,first one lasted 18 months,second one lasted 3 months(although it was built shoddy,i found out when i opened it up),i have know bought a good quality one,i have the unit connected to a timer at source which switches the power on and off daily,my question is could this timer switching the power on and off be damaging the dc power supply shortening the lifespan?

 

[duke37]

What is the light? A bulb will have a very low resistance when it is cold. A bulb will run equally well on AC so could be fed with a simple transformer.

 

[BobK]

He said he had an LED aquarium light.

Bob

 

[shawty1]

the light is led,inc. 40 1 watt cree led's, the power supply is 110/220 ac input 12v dc 5 a output,my concern is that the constant daily switching on/off is why the supplies are not lasting,i could remove the timer and switch the light on/off at the unit thus leaving the power supply on constantly,do you think this would be better?

 

[BobK]

There should be no problem with the power supply being turned off and on daily. How are the LEDs wired? I think it is more likely that you are pushing the current limits of the power supply. If you have a multimeter, measure the current draw. Depending on on how the LEDs are wired, and I am guessing 20 strings of 2, which would pull 7 amps at the 350ma rating of the 1W LEDs. If it is pulling close to, or, heaven forbid, more than 5A, get a more robust power supply.

Bob

 

[shawty1]

thanks for the help Bob,the light has 3 rows of 12 white and 4 blue moon lights,it was sold with the 5a power supply however i will put a meter on it and check it out