Powering LED's

[Gary Hair]

This may seem like it's not an engraving topic but it is, it's for lighting in my sandblast cabinet in which I engrave bricks...

So... I have a 180 watt led light bank that will run on 9vdc to 30vdc. At 9vdc that's 15 amps. I don't have a 15 amp power supply but will have one late next week - of course I need to get some work done today. So my question is - can I run it off of a lower amperage supply without causing any damage? I'm not so concerned about the power supply but I'd rather not damage the lights. Will the lights just be dim? Will they heat up more than if I had the correct PS? Will the PS heat up because it's being used to its maximum?

[Bill George]

Frankly, I would run it off a 12 volt battery, OR do you have an old computer power supply from a few years ago that might work. Otherwise the ohms law thing, yes it will overload a lower amp power supply.

[John Lifer]

As far as I know, it would just be dim.. You can cut off these rolled LED strips and use lower amp power supply, too much and they do burn out.

[Glen Monaghan]

LEDs have a maximum thermal rating and maximum current for which they are designed. Running them at lower voltage and/or current simply operates them at lower temperature and current, and won't harm them. However, if you use a power source which is not capable of providing the amount of current the LEDs "want" at the source's nominal output voltage, then the LEDs will draw all the current the source CAN supply, at which point the supply voltage may be pulled down (such as if you are using a small chemical battery like a 9V transistor battery) and/or the supply may start to current limit (an under-rated electronic bench supply would see the LEDs as something like a short circuit and so reduce output current in order to avoid damage to its output stage).

Basically, the LEDs would be dimmer than normal but not harmed by running off a lower amperage supply, but the supply could be damaged or not, depending on the characteristics/design of the supply.

[Gary Hair]

Thanks everyone! I'm going to forge ahead with this power supply and just keep an eye on it. It's expendable but I don't want to have it overheat, short, catch fire, etc. It will be in my direct line of view so it shouldn't be a problem keeping close tabs on it.

[Rich Harman]

So... I have a 180 watt led light bank that will run on 9vdc to 30vdc. At 9vdc that's 15 amps....

At 9 Vdc it would be 20 Amps.

Are you sure it is a 180 Watt light, or is it a 180W equivalent light? My entire shop is lit by 144 Watts of LED lighting - that's sixteen 60W equivalent LED bulbs that actually use 9W each.

[Dave Sheldrake]

Anybody remember the bit in National Lampoons Christmas Vacation when Grizwald turns the house lights on?

That's gonna be Gary's house

[Gary Hair]

At 9 Vdc it would be 20 Amps.

Are you sure it is a 180 Watt light, or is it a 180W equivalent light? My entire shop is lit by 144 Watts of LED lighting - that's sixteen 60W equivalent LED bulbs that actually use 9W each.

You are absolutely correct, at 12v it is 15 amps. Yes, it's 180 watts. It's a light bar for off-roading. I don't believe you can have too much lighting in a sandblasting cabinet.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Gary Hair]

Anybody remember the bit in National Lampoons Christmas Vacation when Grizwald turns the house lights on?

That's gonna be Gary's house

That's about right...

[Bill George]

If you say put it on a very small 12 v battery with not enough amp capacity it may light up for a few minutes and then get dimmer as the battery ran down. On a plug in power supply with low amp capacity same thing only you might see the smoke rolling out after a minute or so. Unless the PS was self protected- limited or had a fuse or CB.