# Q & A: batteries for LED lights

Q:
so I'm trying to find the most lightest way possible to make a handheld underwater giggind light. i found 12v led lights (HERO-LED MR16-DIM-24T-...12V LED...4.8W, 50W Equivalent,) and i am stuck on the question, can 4AA light one of them? possibly 2? Im looking at the rechargeable batteries that have 2300mah and i understand that 4 of them together make 4.8v and have 10.58 watts. But what does this all mean?? I'm stuck on the volt difference and how long it will even last with these batteries since they are only 4.8v. Is there an easier solution like a different battery type or size? 9v? i want it to be coast effective and light weight. Thanks!
- Seth (age 19)
San Antonio, Tx, USA
A:

These lights really need 12V batteries. V= 12V says how hard the current (I) is being pushed, and if it isn't hard enough almost no current will flow and there will be very little light. You can either get a 12V battery or put say 10 1.2V batteries in series.

Since the power drawn is P=4.8W, and P=IV, I=0.4 amps = 400mA. So to run the lamp for 5 hours you'd need batteries with a capacity 5*400= 2000 mA-h. A quick glance online turns up 12V rechargables with 7Ah (7000mAh) for \$18, but they're lead-acids and a bit heavy. You could no doubt find some sort of lithium-based batteries that would be lighter, but pricier.

Mike W.

(published on 01/30/2016)