BTS7960 Turned Into A 12V (18Vmpp) PV Camp Water Heater part 3 Improved Timing
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- Опубліковано 8 лют 2025
- Timing is everything. By replacing resistors with a couple of diodes, the cycle times shorten and the delta voltage tightens. With the prior video there was about a 5:1 resistive voltage divider. The enable pin will see a voltage change reduced by that much. Zeners will just subtract that voltage and the delta voltage change at the sense pin will be much larger. That will make the delta swing on the capacitor bank smaller and increase efficiency. More zeners can be added for higher voltage. Even the forward voltage (0.7V) of silicon diodes can be used for a fine adjust.
A packet of 100 diodes is cheap. The zeners could all be replaced with diodes. The three 5.1V zeners could be replaced with 24 or more diodes placed in heat shrink tubing. With those exposed to outside air, they will provide temperature compensation to nearly match that of the panels. Seven diodes could replace the 5.1V zener. However, if exposed to the same temperatures the compensation of the other diodes will be negated. If the control is in a more stable temperature area, you still get the temperature adjustment benefits. 10K 1/8W resistors are cheap and allows only one resistor value to be ordered. They can be put in parallel or serial to obtain value needed. The 0.22uF capacitor can be between 0.12 and 0.33uf. - Наука та технологія
Timing is everything. By replacing resistors with a couple of diodes, the cycle times shorten and the delta voltage tightens. With the prior video there was about a 5:1 resistive voltage divider. The enable pin will see a voltage change reduced by that much. Zeners will just subtract that voltage and the delta voltage change at the sense pin will be much larger. That will make the delta swing on the capacitor bank smaller and increase efficiency. More zeners can be added for higher voltage. Even the forward voltage (0.7V) of silicon diodes can be used for a fine adjust.
A packet of 100 diodes is cheap. The zeners could all be replaced with diodes. The three 5.1V zeners could be replaced with 24 or more diodes placed in heat shrink tubing. With those exposed to outside air, they will provide temperature compensation to nearly match that of the panels. Seven diodes could replace the 5.1V zener. However, if exposed to the same temperatures the compensation of the other diodes will be negated. If the control is in a more stable temperature area, you still get the temperature adjustment benefits. 10K 1/8W resistors are cheap and allows only one resistor value to be ordered. They can be put in parallel or serial to obtain value needed. The 0.22uF capacitor can be between 0.12 and 0.33uf.
Really nice project. A modified water thank with two heat elements where you used the bottom one for solar and the top one for domestic electricity would probably give a ROI ( return of investment) in a week or two.
Another interesting use would be in a thermal storing cook top (Not sure what it is called in english) Big lump of insulated iron with a 50-100W heating element. It was common over here around 1940-60.
Anyway, a comment for the algorithm.
Thanks for sharing your insights and projects like this.
These modules seem nice until they aren't. These are far too fragile for neophytes and one wrong move they are toast. The same thing can be accomplished with a LM358 and a FET. A lightning hit results in a repair of less than $1.
I'm working right now on a cooker. I have a very inefficient, as far as heat loss, but will be able to show power point heating if standard 120VAC appliances with 0ne or two 12V 100W panels.