I have the following things:
- 24VDC wires through the house for lighting and more.
- A 24VDC 10A power supply, can be adjusted with a potentiometer between 22V and 28V (more than the specified +-10%).
- Two 12V 7Ah lead batteries.
Now I want to combine them to get an uninterruptible light source.
Today I fixed my battery light. I changed R15 to 39k, and for R14 I had used 33k since I didn’t have anything between 22k and 33k. The threshold voltage is now at most 7.3V so this rubbish wire can make a voltage drop of over 4V and it will still work. And just for testing I’ve put a 470uF cap instead of the 100nF for C5. I left this one inside, it makes a nice delay for the LDR just in case some stray light hits it. Here is the updated schema (more docs).
Now I’m happy with it. Except maybe I add a sleeping mode where it makes just enough light to see the walls, or adding a wire to the bathroom and putting a PIR sensor and an LED there, or …
Today I finished version 2 of my battery light circuit: