Hello everybody, I am working on a new project inspired by alternative energy solutions! My idea is to take an ordinary 6v lantern and convert it to a rechargeable lead-alum and 12v LED with an integrated solar panel (9-12v, 0.05-0.1a) and 12v in for charging as well regulated 20w 12v out. This is to take camping, to use as a flashlight and backup 12v power source.
Here is what I have come up with so far:
6v 2aH lead-acid (Sulfuric) converted to lead-salt (Alum) 'crystalline' battery
9-12v solar panel to charge up the battery in the sun
A regulated buck-boost converter; ~1-12vin/vout, 20w (Preferably a charge pump)
12v green LED bulb and base
banana plug sockets for 12vin/vout
adjustable brightness
Alright, now let me go into some detail:
First off, the battery is a lead-acid converted to lead-alum, which exhibit around 4.8v standing voltage and 3a peak current at a fresh charge. In great depth of discharge, below 2.4v, the current drops to around 0.05-0.075a. As it goes, these cells do not 'sulfate to death' during deep discharge and also re-charge quite effectively. The typical power is around 1w continuous. The battery seems to prefer charging at a rate of 12v 0.1a.
The 12v regulated output and 12v LED bulb were chosen for extensibility of the system. It is my desire for the flashlight to double up as a portable power source. The losses should be minimized absolute. When using this unit, it may not have a consistent supply voltage and re-charge cycle. Keeping this in mind, I would like to be able to use it even when the battery cell drops below 1.5v. For this, I will need a buck-boost DC-DC power converter that can accept a ~1-12vin, 12vout and up to 20w power dissipation, even if I never end up placing it on that kind of load. Also, the power supply mode should work even when the LED bulb is off, by flipping a bypass switch or something.
I choose 12v LED green color because of the increased visibility of surroundings at night. Red is also an option for night eye considerations. Regardless, the plan is to use an ultra-bright 12v LED auto bulb; for simplicity. Of course, I would also like adjustable dimming (and possibly strobe function?).
I had some questions I hope some of you might be able to answer. For example:
What is the best way to provide stable 12vout from a fluctuating 1-12vin that has 20w rated power dissipation and is efficient as possible? I am thinking charge pump, because there is minimal magnetic inductive losses, but where to find one/how to make one with the handling capability?
How does one create a buck-boost regulated switching capacitor charge pump from scratch?
How can I protect all the components from damage without loosing power?
Can anyone recommend a 12v solar panel that has 5cmX10cm dimensions?
Here is what I have come up with so far:
6v 2aH lead-acid (Sulfuric) converted to lead-salt (Alum) 'crystalline' battery
9-12v solar panel to charge up the battery in the sun
A regulated buck-boost converter; ~1-12vin/vout, 20w (Preferably a charge pump)
12v green LED bulb and base
banana plug sockets for 12vin/vout
adjustable brightness
Alright, now let me go into some detail:
First off, the battery is a lead-acid converted to lead-alum, which exhibit around 4.8v standing voltage and 3a peak current at a fresh charge. In great depth of discharge, below 2.4v, the current drops to around 0.05-0.075a. As it goes, these cells do not 'sulfate to death' during deep discharge and also re-charge quite effectively. The typical power is around 1w continuous. The battery seems to prefer charging at a rate of 12v 0.1a.
The 12v regulated output and 12v LED bulb were chosen for extensibility of the system. It is my desire for the flashlight to double up as a portable power source. The losses should be minimized absolute. When using this unit, it may not have a consistent supply voltage and re-charge cycle. Keeping this in mind, I would like to be able to use it even when the battery cell drops below 1.5v. For this, I will need a buck-boost DC-DC power converter that can accept a ~1-12vin, 12vout and up to 20w power dissipation, even if I never end up placing it on that kind of load. Also, the power supply mode should work even when the LED bulb is off, by flipping a bypass switch or something.
I choose 12v LED green color because of the increased visibility of surroundings at night. Red is also an option for night eye considerations. Regardless, the plan is to use an ultra-bright 12v LED auto bulb; for simplicity. Of course, I would also like adjustable dimming (and possibly strobe function?).
I had some questions I hope some of you might be able to answer. For example:
What is the best way to provide stable 12vout from a fluctuating 1-12vin that has 20w rated power dissipation and is efficient as possible? I am thinking charge pump, because there is minimal magnetic inductive losses, but where to find one/how to make one with the handling capability?
How does one create a buck-boost regulated switching capacitor charge pump from scratch?
How can I protect all the components from damage without loosing power?
Can anyone recommend a 12v solar panel that has 5cmX10cm dimensions?
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