Powering a strip LED 13v 240ma with 2 9volts how to question:

[jscott70]

I apologize in advance if I posted in the wrong place as I am new here.

I have a 12 series LED light that requires 13v at 240ma and would like to power it with 2 9v batteries.

What would be the best configuration to make this work? I was thinking of putting the batteries in a series and using whatever to drop the voltage and amperes to provide a longer life for the light.

Sorry if this is a stupid question for you genuises out there!

Thanks,

 

[MikeMl]

Two 9V batteries will run your LEDs for less than 1.6 hours. If you really want to be replacing batteries that often, connect them in series, and connect a 20Ω 2W resistor between the +18V and the positive input to the LED strip.

 

[jscott70]

How about 4 9v?

I am working with limited space but can accommodate 4 9volts in a series.

If I can pull a burn time of 3 hours per session before needing to replace the batteries, I would be fine with that.

Thank you very much for the help!

 

[MikeMl]

I am working with limited space but can accommodate 4 9volts in a series.

If I can pull a burn time of 3 hours per session before needing to replace the batteries, I would be fine with that.

Thank you very much for the help!

Make two sets of two-in-series. (+- +-)
Connect the two strings in parallel (+ to + and - to -)
use the 20Ω resistor as described before.

 

[Hero999]

Use 10 AAA cells.

The voltage will be 15V when new and 10V when old, the lights should be able to work from both extremes of voltage.

 

[jscott70]

10 AAA's

According to the Mfr. of the light anything under 13 requires a heatsink. Am trying to avoid a complicated system but if there is a better power source option, I am game.

Thanks,