# How much battery power for LED and how to make it flicker

I am trying to figure out what configuration of battery(ies) I need to power this LED. I am only using one (specifically the warm white 1-up).

I am also looking to make it flicker like a candle with the smallest item possible that will NOT reset every time it is turned on/off. I need to to always turn on and flicker correctly. EDIT/ADD: Is there a resister I can include in a simple circuit with a battery pack to make it flicker? It seems like thats what a lot of the cheap tea lights use.

For context I am trying to make super bright LED candles. So everything I use needs to be able to fit into a smallish pillar candle (~1.5-2.5" diameter x min 6" height). And I am on a pretty tight budget, so please let me know what are the cheapest options.

Thanks!

• What do you mean by "not reset when every time it is turned off". Reset what? The thing you describe has no memory to forget anything when turned off. – DKNguyen May 21 at 20:12
• I have used string lights and other things before that have multiple modes and it resets back to the beginning of the mode options every time it is turned on. – Nova May 21 at 20:17
• Those are simple, stupid LEDs. No worries about resetting a controller. Just about supplying the current. Maximum brightnes (1.5 ampere) is a lot for a battery if you want it to last for a while. – JRE May 21 at 20:22
• Lasting even 1-2 hours would be great. – Nova May 21 at 20:51

That's a high quality LED (if genuine) - depending on volume then an Asian sourced semi-equivalent would be much cheaper.

Battery life is very very dependant on operating current.
For a battery of adequate voltage across the operating time

• Operating life = Battery_mAh_capacity / LED-mA.

If you operate the LED at 700 mA then

• 3 x AA Alkaline cells with a capacity of ABOUT 3000 mAh would ooerate the LED for about
time = battery_mAh/LED_mAh = 3000/700 = 4+ hours.

• A rechargeable 18650 LiIon cell of 3000 mAh would provide similar operating time.

If "cheating" is acceptable, using an existing (low cost) low power flickering-candle-LED to drive your power LED, similar to this circuit by the great Dave Johnson, or a simple but elegantish version here.

Alternatives could be a low cost microcontroller (from about 20 cents US) - ATtiny85 example here and ATtiny13 version here or a counter IC connected to form a pseudo-random number generator.

Many ideas here - Google image search on - candle flicker circuit

• So I could I use 4 x AA alkaline batteries (just to get a battery holder that will fit in my candle)? – Nova May 21 at 22:40
• @Nova You will need a means of regulating the supply to suit the LED and any circuitry. 3 x AA = about 3.3V - 4.5V flat to new. 4 x AA = 4.4V - 6V . You will get NO MORE lifetime with a linear regulator from 4 cells than you get from 3. With a switchmode regulator you get SLIGHTLY more. You still need to decide on a Flicker-circuit. You can use a 4 x AA holder with 3 x AA by soldering a wire across one of the positions - be SURE that a cell never gets inserted in that position. – Russell McMahon May 22 at 11:46