Dear members,
I want to connect around 30 leds in parallel across a 6v, 4ah capacity battery...... as per my lab test, each led consumed 16mah at 3.2 V when connected directly across a rps supply. when i connected an led through a resistor...the current consumed was reduced to a great extent. Now what would be the best way to connect the leds across the battery? also, i would like to know if there are any circuits that i might need....
You have 6 Volts supply and 3.2 Volts LED's.
Then you have to drop 2.8 volts in series resistor.
And run LED at 16 mA
From U = I * R
2.8 / 0.016 = 175 OHMS.
I would use a 180 ohms 1/4 or 1/2 Watt resistors in series with each LED.
Do not put the LED with no resistor across the 6 Volts because it will burn the LED's out,
current will be a lot higher and the LED will fail.
The amount of light you can create in a limited space is much higher for LEDs that for florescent lights, at least on a small scale. You don't see many florescent tubes on key fobs do you?
Cold cathode tubes have one of the same limitations as florescent tubes do they're extrmely fragile. LED's can withstand pretty much any physical shock that can be placed on them that doesn't physically disintegrate what it's made out of.
Like audioguru said, basically as long as you provide the proper voltage to an LED it will work for the effective lifetime of it's user.
The important thing to point out is that you MUST give each LED its own resistor. You cannot simply calculate for one big resistor due to the LED's properties.
I know that's inconvenient, but any attempt to put LEDs in parallel without their own resistors will typically damage them in short order.
Obviously when replacing the bulbs is hard/expensive it make sense and coloured LEDs are probably as or even more efficient than coloured fluroscents.
Electricity is expensive so using LEDs to light an office would still cost more than fluroscents even when you consider the cost of replacing the tubes.
My point is it depends on the application for efficiency fluroscents are best for conlong life LEDs are best.
Let's consider this application, a small high quality CCT can have a life of 10,000 hours, that's 416 days and 16 hours. LEDs will last 10 times as long but the CCT is three times as efficient and so the battery will last three times as long. Given that batteries are more expensive to replace than either LEDs or tubes, tubes will work out cheaper since either way the batterry will need replacing less often and the tube will still out last the battery.