Hello:
This is my first post on this forum - I only know enough about electronics to get started on something, but not enough to prevent a FUBAR. So please excuse any protocol miscues.
First the situation, then the question further below.
For my sailboat interior lighting, powered by the systems 12 volt deep cycle batteries, I am converting the OEM incandescent 15w bulbs to warm white LED's. Last night I succeeded using a LM317 to provide, from a 12 volt auto battery, a constant 6.4 volts to an array 2 x 3.2v (20 MA each) LEDs in series x 7 in parallel (= 14 total LED's). The LM317 I noticed got very warm, but not overly hot. I decided on the LM317 to regulate, because the source voltage can be from about 14.x volts when the alternator is running, or down to (say) 11.8 volts if the battery bank becomes depleted. Also I wanted enough head room voltage so that the LM317 would provide the constant 6.4 volts.
Question is: Will the circuit be more energy efficient if I set for V(out) to be 9.6 volts (for 3 x 3.2v in series x 5 = 15 LED's) than my arrangement of 2 x 3.2 volts. It would seem to me that the LM317 wouldn't have to dump as much energy in the form of heat: i.e. 12v average Vin to to 9.6 Vout vs. 12v average Vin to 6.4 volts Vout.
Thanks in advance for your advice.
regards,
rardi
This is my first post on this forum - I only know enough about electronics to get started on something, but not enough to prevent a FUBAR. So please excuse any protocol miscues.
First the situation, then the question further below.
For my sailboat interior lighting, powered by the systems 12 volt deep cycle batteries, I am converting the OEM incandescent 15w bulbs to warm white LED's. Last night I succeeded using a LM317 to provide, from a 12 volt auto battery, a constant 6.4 volts to an array 2 x 3.2v (20 MA each) LEDs in series x 7 in parallel (= 14 total LED's). The LM317 I noticed got very warm, but not overly hot. I decided on the LM317 to regulate, because the source voltage can be from about 14.x volts when the alternator is running, or down to (say) 11.8 volts if the battery bank becomes depleted. Also I wanted enough head room voltage so that the LM317 would provide the constant 6.4 volts.
Question is: Will the circuit be more energy efficient if I set for V(out) to be 9.6 volts (for 3 x 3.2v in series x 5 = 15 LED's) than my arrangement of 2 x 3.2 volts. It would seem to me that the LM317 wouldn't have to dump as much energy in the form of heat: i.e. 12v average Vin to to 9.6 Vout vs. 12v average Vin to 6.4 volts Vout.
Thanks in advance for your advice.
regards,
rardi