Nice explaination, breaks it down. I have probably had my Halogen floods light on no more then a couple of times because they drain the battery quick. But I might use LED flood lights much more if I knew they wouldn't drain the battery as quick. What do you think of these, twice as bright as the ones you recommended, but of course they probably use twice as much power.
http://www.northerntool.com/shop/tools/product_200498862_200498862?cm_sp=UpsellsTop%20SellersProduct%20Page
I would be careful about the track record and quality of LED lights I would buy. They are a relatively new technology and it requires careful design and testing to achieve life and performance that makes them superior. The useful life of LED lights is dependent on precise current control, thermal management and environmental protection.
Current control: The good lights will have current limiting circuits for each LED element, many low cost lights have one current limiting circuit and all the LED's are in parallel. This makes for a light with a much shorter life.
Thermal control: LED typically have a 50,000 hour useful life (useful life is generally defines as the point when the light output decreases to 70% of the original output) at 25 degrees C, but as operating temperature increase life decrease dramatically. Quality LED lights will have a finned aluminum housing designed to help dissipate waste heat.
Environmental control: LED life and light output is degraded by exposure to humidity and corrosive environments such as salt spray. For outdoor applications look for a minimum IP rating of IP66 (protected against Powerful water jets) or better yet IP67 (protected against immersion up to 1 meter) or IP68 (protected against immersion greater than 1 meter).
Regarding the
http://www.northerntool.com/shop/tools/product_200498862_200498862?cm_sp=UpsellsTop%20SellersProduct%20Page that you asked about. I have no information as to the quality of these lights. I searched for reviews but didn't find any.
I suggest that you determine how many Lumens you need and then search for lights that provide that. For example the halogen flood light produce 1,000 lumens. If you want 1,000 lumens the you could look at this one for $60
http://www.northerntool.com/shop/tools/product_200498858_200498858 it is 12 V, 15 Watts and 1,150 lumens.
Also RI has a set two Dually lights for $199.99
http://www.rigidindustries.com/Dually-2x2-Diffused-LED-Lights-Set-of-two-p/20251.htm and since they draw 15 watts they would give the same run time as the Northern Tools light above but they produce 1,300 lumens. Personally I go with the RI lights and pay the extra $40 to know I'm getting a quality light that will last a long time.