I am getting ready to do an amp rack and i want to run some led's to light it up. I was wondering if I was to run say 3, 4, 5 or 6 Cree XRE Q5 led's in series would this be ok without a driver? How many amps would they draw approximately? Do I have to run a driver or could I just run them in series with a fuse and switch right off the electrical system of the car?
How many lumens could I expect out of each of these. The lights will be on sometimes with the engine off as well as with the engine on, I assume they would be brighter when the engine is on.
Would I be better off with a 1000ma driver? how much brighter would it be with a driver?
Re: 3, 4, 5 or 6 Cree XRE without driver possible??
In short, no you cant really run the LED's without a driver.
It will be 100% safer to run them with a LED Driver and it wont even cost that much. If you are running these in your car there are a number of LED Drivers avaialble for you. I've always found that http://LEDSupply.com is a great company and makes good products. You can use the BuckBlock drivers for up to 3 LED's in series, or you could use the FlexBlock for up to 8 LED's in series all at 700mA.
You can calculate the output of different cree LED's here: http://pct.cree.com/ but if you ran 6 XR-E Q5's at 700mA each you would get 181 lumen each or 1086 total. There are other LED's out there that are Much more efficent if you are looking for brighter as well. The Cree XT-E R5 will give you 283 lumen for the same amount of power.