Buck Gizmo -Volts vs Amps ? UPDATED
Update 5 Nov. (It didn't work out as hoped) I got my little gizmo, see close-up photos here http://www.ebay.com/itm/DC-DC-15A-Converter-Buck-Adjustable-4-32V-12V-to-1-2-32V-3-3V-5V-24V-Step-Down...
Forum Discussion
I am back to being totally confused but that's ok :)
I have been stuck on the input side as though the DC supply was "on" when in fact it is a "demand" set-up. The solar panel is out there in the sun but nothing is happening. Same as the water pipe out there with the tap turned off.(sort of?)
So how do you turn on the tap for that solar panel? You have to go back and start with the battery, which has a voltage and can accept some amps. Connect that to the output of the buck converter and now that battery voltage is the buck converter's output voltage, no matter what you set CV at, but if you want any amps to go to the battery you have to let CV be higher than battery voltage.
So now connect panel to buck converter input and amps flow. The battery is the demand. I have not got my mind around how the input and output ratings work within the watts boundaries when it is the amount of demand that is running this.
I think MPPT twiddles voltage where it is so out at the panel at the other end of the wire, it stays near Vmp (30v with my 230w panel)and what amps that comes to is a by-product not a setting of any kind.
So your DC intake at the buck converter is something or other in watts and has a certain voltage and is related to the output demand which varies with the load, not the CV you picked, so the battery is running the whole thing.
I don't understand how it is the watts difference that creates the demand when we are told it is the voltage difference across a resistance that creates the amps and then you get your watts from that. But the watts are fixed so you get more amps if you lower the voltage. Some kind of chicken and egg thing I guess. I am back to square one, and I hate watts even more than before! :(
I have been stuck on the input side as though the DC supply was "on" when in fact it is a "demand" set-up. The solar panel is out there in the sun but nothing is happening. Same as the water pipe out there with the tap turned off.(sort of?)
So how do you turn on the tap for that solar panel? You have to go back and start with the battery, which has a voltage and can accept some amps. Connect that to the output of the buck converter and now that battery voltage is the buck converter's output voltage, no matter what you set CV at, but if you want any amps to go to the battery you have to let CV be higher than battery voltage.
So now connect panel to buck converter input and amps flow. The battery is the demand. I have not got my mind around how the input and output ratings work within the watts boundaries when it is the amount of demand that is running this.
I think MPPT twiddles voltage where it is so out at the panel at the other end of the wire, it stays near Vmp (30v with my 230w panel)and what amps that comes to is a by-product not a setting of any kind.
So your DC intake at the buck converter is something or other in watts and has a certain voltage and is related to the output demand which varies with the load, not the CV you picked, so the battery is running the whole thing.
I don't understand how it is the watts difference that creates the demand when we are told it is the voltage difference across a resistance that creates the amps and then you get your watts from that. But the watts are fixed so you get more amps if you lower the voltage. Some kind of chicken and egg thing I guess. I am back to square one, and I hate watts even more than before! :(
