Bit of a newbie question here...
I want to build a battery powered LED light for use outdoors. So basically needs to be pretty bright and last a while.
If I have battery rated like this:
5.0Ah 6V Discharge current 20 hr rate 250mA Capacity: 20hr rate (0.25A) 5.0Ah 10hr rate (0.50A) 4.3Ah 5hr rate (1.00A) 3.8Ah 1hr rate (2.70A) 2.7Ah
An LED rated like this (lumens):
Forward Voltage: 3.7V @ 350mA : 100 @ 500mA : 130 @ 700mA : 185 @ 1,000mA : 250
So I want to create a circuit where I can switch between using 0.25A and 0.5A from the battery.
So, if I were to create a circuit with just the battery and LED, would the LED draw the maximum current it is able to? (lets say that's 1A, so it lasts 5h) Or would the battery dump all it's power into the LED since there is no resistance in the circuit?
To get the circuit running at 0.5A, by Ohms law, I would need to add in a 12 Ohm resistor (I think! - 6V / 0.5A)
Does the addition of the resistor reduce the power drain of the circuit?
Do the resistors regulate the current from the battery in a way that will extend the life of the battery?
Also, if the forward voltage for the LED is only 3.7V in a 6V circuit, how would I go about reducing the voltage for the LED?