Before I posted this, I did a quick search here on several variations of the topic above but didn't find quite the answers I'm looking for.
However, a while back this forum was very helpful with a similar project and I was able to build a protection circuit that is still in use today and has been perfect. With a few differences, that circuit might work here as well but in this new project, there are 3, 1.2v batteries instead of two and I do not need an LED indicator in this new project. Also, the previous circuit was not a cut-off, just a warning. Here is a link to that project.
https://forum.allaboutcircuits.com/...ed-lower-threshold.141757/page-3#post-1216269
So I need a similar circuit that does not utilize an LED, and that stops the flow of current below approximately 3.6v DC
The circuit in this new project consists of 3, 1.2v rechargeable NiMh batteries. The device is a motion activated, outdoor LED light we use above our garbage cans to automatically illuminate the area when I take garbage out at night. The problem is that the device KILLS batteries because it will continue depleting them until they are at zero voltage.
It uses 3, D Cells in Series so the total voltage is of course approximately (1.4v x 3 cells) = 4.2v fully charged.
What I want is to add a battery protection circuit that will stop the device from drawing current from the batteries when the voltage drops below the per cell voltage minimum of 1.2v or (1.2v x 3) = 3.6v
It would be nice to start with a POT to be able to adjust the cut off voltage over a range of maybe 3.9v to 3.0v, then after finding the best compromise, replace the POT with a resistor.
If there is already a thread with such a thing (pretty sure there is), I didn't find it so a link would be great if it already exists.
If not, this should be a very easy thing to do using a TL431 ?
However, a while back this forum was very helpful with a similar project and I was able to build a protection circuit that is still in use today and has been perfect. With a few differences, that circuit might work here as well but in this new project, there are 3, 1.2v batteries instead of two and I do not need an LED indicator in this new project. Also, the previous circuit was not a cut-off, just a warning. Here is a link to that project.
https://forum.allaboutcircuits.com/...ed-lower-threshold.141757/page-3#post-1216269
So I need a similar circuit that does not utilize an LED, and that stops the flow of current below approximately 3.6v DC
The circuit in this new project consists of 3, 1.2v rechargeable NiMh batteries. The device is a motion activated, outdoor LED light we use above our garbage cans to automatically illuminate the area when I take garbage out at night. The problem is that the device KILLS batteries because it will continue depleting them until they are at zero voltage.
It uses 3, D Cells in Series so the total voltage is of course approximately (1.4v x 3 cells) = 4.2v fully charged.
What I want is to add a battery protection circuit that will stop the device from drawing current from the batteries when the voltage drops below the per cell voltage minimum of 1.2v or (1.2v x 3) = 3.6v
It would be nice to start with a POT to be able to adjust the cut off voltage over a range of maybe 3.9v to 3.0v, then after finding the best compromise, replace the POT with a resistor.
If there is already a thread with such a thing (pretty sure there is), I didn't find it so a link would be great if it already exists.
If not, this should be a very easy thing to do using a TL431 ?