I have been reading through a good many great articles here, trying to sort out the current limiting situation with series LEDs, on 12v. My main objective is to have very powerful homemade LED boards running on solar charged batteries. There is no concern about them running "while charging takes place"... due to the fact that the solar system would be adding very little charge on a day where the building actually needed this light on (the building also has natural light). They could be shut off when a genset was used.
I've read several of Bill's great articles on using voltage regulation, and I have read a number of threads here.
MY main objective is to build arrays of 24 8mm LEDs, initially bright whites and later warm whites. The spec on the bright whites is 3.2v / 100mA / 110,000 MCD ea.
The solar system bank varies from 11.5v to 12.6v.
I was initially thinking I could use an LM350 to voltage regulate to 8v, and calculate resistors from there.
When I do the calculations, I am amazed at how much energy is wasted on heat! WOW. Then again... incandescant bulbs are LIKE HEATERS, so I guess it's not so bad afterall.
Is it possible to use tiny light bulbs in series instead of resistors, or does anyone know of any clever "use" for this energy?
If not, please take a stab at this theory:
Could I settle for arrays of 12 - voltage regulate to 7.2v, use 8.2 ohm 1/4 watt resistors instead, and
together, all resistors dissipate 492 mW
together, the diodes dissipate 3840 mW
total power dissipated by the array is 4332 mW
the array draws current of 600 mA from the source.
Is it possible to get that precise?
Does dropping the voltage that much lose a lot of energy within itself?
I kind of like this method too in that the lamps would work on two lithium cells as well. They are getting cheap now, you can get a 4000 mAh 3.6v battery shipping included for $3.
Thanks
I've read several of Bill's great articles on using voltage regulation, and I have read a number of threads here.
MY main objective is to build arrays of 24 8mm LEDs, initially bright whites and later warm whites. The spec on the bright whites is 3.2v / 100mA / 110,000 MCD ea.
The solar system bank varies from 11.5v to 12.6v.
I was initially thinking I could use an LM350 to voltage regulate to 8v, and calculate resistors from there.
When I do the calculations, I am amazed at how much energy is wasted on heat! WOW. Then again... incandescant bulbs are LIKE HEATERS, so I guess it's not so bad afterall.
Is it possible to use tiny light bulbs in series instead of resistors, or does anyone know of any clever "use" for this energy?
If not, please take a stab at this theory:
Could I settle for arrays of 12 - voltage regulate to 7.2v, use 8.2 ohm 1/4 watt resistors instead, and
together, all resistors dissipate 492 mW
together, the diodes dissipate 3840 mW
total power dissipated by the array is 4332 mW
the array draws current of 600 mA from the source.
Is it possible to get that precise?
Does dropping the voltage that much lose a lot of energy within itself?
I kind of like this method too in that the lamps would work on two lithium cells as well. They are getting cheap now, you can get a 4000 mAh 3.6v battery shipping included for $3.
Thanks