Solar 9V PIR

426

05:03:53

Solar Panel (12v-14v depending on sun) putting out 0.34 A on my Fluke to charge a 300mA NiMH 9v battery during the day, and then solar acts like a night detection to allow current flow from the battery to a SkyLink ID-318 wireless motion detector (depicted by the lamp) which operates 9v @ 10mA.

Would appreciate any advice to making it more efficient or just plain better.thanks

published 6 years ago

bakupcpu

6 years ago

Good day, your circuit should work as intended but you might want to add over voltage protection to the battery for those long sunny day of summer. You can also accomplish the same result using a pnp transistor. If you are concern about saving every power for the light you can use mosfet. Hope this help! Cheers

rich11292000

6 years ago

How many nimh cells? What is the manufacture spec of the the solor cell? 300mA of charging Vs 10mA of discharge, your going to overcharge the battery for sure.

solarczar

6 years ago

I did try to use a PNP design. I'll draw it up and post. Always thought a mosfet would have been overkill, so thanks for the advice. I'll look into it. As for rich, I have 1x 9v 300ma NiMH battery. A typical alkaline battery will last about 2 weeks, so was hoping the NiMH approach would be better suited for longevity. Any advice on a simple way to reduce battery overcharge?

solarczar

6 years ago

Bakupcpu, can you shoot me some links for really simple over charge protection. I'm limited on space, and all the designs I've seen are too big

bakupcpu

6 years ago

You could use a simple zener diode or add a few diode before your circuit, even led would work as well. I could see what I could find online and publish it in here. Cheers!

bakupcpu

6 years ago

Have you found a good solution? I just remembered that you could use a tl431 shunt regulator it's basically 2 resistor and a 3 prong device the size of a transistor. You can set them to almost any voltage you need. Hope this help.

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