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how to power 9 10 watt leds from a automotive battery? Answered

I am building a under water array using 9pcs  10 watt green leds, and will be powering from a automotive battery. the led data is.
10 watt green
900 lumens
voltage dc 9-10.8 
current 900mA
integrated approach 3 and 3
My current build has them in parallel due to not wanting to lose all leds if one fails but will change this if its not possible. I am having issues finding  a step up dc to dc adjustable driver that will allow a output of 10.8 volts an a current of 8100mA . Anyone have ideals or a better solution. Thanks.


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4 years ago

can't be run with a constant VOLTAGE supply. They need a constant CURRENT, and ideally you would put them in series, but since 9 x 10V is 90 odd volts, you won't want to immerse it either.

You could find a 3Ohm
resistor, rated at 3W, and run EACH of them with a resistor on a 12V
supply in parallel arrangements. You will be burning an extra 30W for
your 9 LEDs.

An alternative is these very cheap regulator blocks


These will run very nicely on EACH LED, and reduce the wasted power.

Then, as DU35M says, you need to worry about the supply requirements.


4 years ago

You need proper LED driver for this.
There is a reason why a complete LED lamp often costs a lot more than just the LED module ;)
Considering the limits of a car battery and the power requirements you won't have long running times either.
Even a proper deep cycle battery would need to be of considerable size to allow for proper run times.
The keyword here is AH - ampere hours.
But you also need a battery that is able to provide the current you need.
For example a battery with 20AH and a max current limit of 10A would only power the LED's for a bit over 2 hours a 50AH battery for around 6 hours...

Better option would be a parallel/series combination of LED's with only 4 or 6V requirements...
Of course that still requires proper drivers for these high power LED's....