Looking for a little help with LEDs

[CompleteDestruction]

Looking for a little help with LED strips... its not going on a helicopter, but i thought i would still ask for help.

This is on an older car running a 6v battery, so maybe up to 9v when running.

I will be running about 30" of red off one power.

And 2 36" strips of white and 2 48" strips of white off another power.

Do i need resistors? Will i need 5 resistors or 2?

Thanks guys.

Please dumb it down for me!

[gstoneberg]

The light strips I have used already have resistors installed which are designed for a 12v supply. I have run a white resistor strip off a 2s lipo (7.5-8.4v) and it worked fine, though dimmer than they are at 12v. I'm not sure the other colors would work like that, you'd have to try them. If the voltage applied to the LED does not exceed the forward voltage it requires they won't light at all. Different colors have different forward voltages. You may find that 6v doesn't light them, but 9v does. I don't know if you can buy light strips designed for a 6v input or not. If you use individual LEDs, then you'll need to insert a resistor in the circuit to limit the current. Since resistors are made over a wide range of resistance values there's no need to put in multiples. There are LED resistor calculators which you can find on the internet which make it easy to determine the correct resistance, and 6v is certainly enough to drive all the LED colors.

Good luck!

[flyinfool]

FWIW
The charging system on your 6V car should be running at ~7 volts.
If these are the premade strips made for 12 V which on a car really means they were made for 14 Volts. It is pot luck as to wether they will light at 6-7 volts. Even if they do light up they will be a lot dimmer than they were at 12V.

On most of the non waterproof light strips, you can take the resistors off and replace them with the correct value for your application. You could either remove and replace them or piggy back another resistor on top of the ones that are there. Either way will work and get you the full brightness that the strips were designed for.