# LED Lighting project

Discussion in 'LEDs and Optoelectronics' started by scutty247, Feb 12, 2013.

1. ### scutty247

8
0
Feb 12, 2013
Hello everyone,

I appreciate an LED lighting project is probably not very original on here but thought I'd start a fresh thread.

I am currently working on a medical lighting system for developing countries. It will be solar charged and use NI-MH rechargeable AA batteries and a commercial 12V LED cluster.

I have the LED cluster and they are 12V and 0.24 Watts each. I would like to use 12 of these as that means a good quality light but it could be slightly less if needs be. Therefore its a 12V strip and 12 would need 2.88 Watts.

My questions are:

1) How many batteries would i need to make it work?
2) How long would I get out of the batteries per charge (ideally I would like 9 hours but 6 is acceptable)?
3) How powerful a solar panel would I need to charge it in 12 hours?

Many thanks for your time. If anyone does any maths please go easy on me as I'm a maths biff!

2. ### BobK

7,682
1,686
Jan 5, 2010
2.88 Watts at 12V is 240ma. An AA size NiMH is likely around 2000maH. So you would get about 8 hours out of a battery made up of 10 cells in series to get your 12V.

The charge them in 12 hours you would need a charge rate of 2000/12 or 166ma ideally, but there are losses, so more like 200ma at a bit over 12V (say 15), or about a 3W panel.

Bob

3. ### scutty247

8
0
Feb 12, 2013
Excellent, thank you. This totally backs up what I have been told but just wanted to confirm.

Thank you very much.

4. ### scutty247

8
0
Feb 12, 2013
Just one more question. If I needed to connect 3 of these lights to one solar panel would i simply triple the power output of the panel? So a 9W panel??

5. ### BobK

7,682
1,686
Jan 5, 2010
Yep. Power does add that way.

Bob

6. ### scutty247

8
0
Feb 12, 2013
Awesome! Thanks again