Hi everyone. I'm new here, but optimistic. I need guidance for a project that requires a low voltage cut-off for a NiMH battery.
The project uses a NiMH battery of 4 AA cells in series to power a simple load of resistors to produce around 1.5 - 2 watts of heat. The heat will help prevent a hummingbird feeder from freezing in temperatures as low as -5°C. Here in Victoria, BC, and in other parts of the Pacific Northwest, the Anna's hummingbird doesn't migrate. Because they are at their limit in the winter nights, at the first light before sunrise they go to their usual feeders and recover from the torpor.
In the past years I had used 5 watt night lights and a layer of aluminum foil to keep the feeders from freezing, but where I live now there are no outdoor outlets. I would make an inductor to transfer electricity through the single-pane basement window, but I don't yet know how to do something like that. I plan to go to college here for an electrical engineering program, but in the mien time there are cold hummingbirds.
I figure with a modest amount of heat from resistors (designed to dissipate the heat) and a foil insulation wrap, I should get a few hours of operation on one set of batteries before I switch them for freshly charged ones.
Back to the task at hand, I need a way of preventing the batteries from over-discharging, as I don't want them to be damaged. I saw this thread but I am unsure which resistor values to change to set the cut-off points. I also saw this forum thread where an IC is mentioned, the MAX8211, however when I look at the spec sheet it looks like it will detect the voltage, and will include hysteresis, but I don't know how to use its output to disconnect the load. Does it simply send a digital signal to be used by a processor? I can't find what NMI means on the output.
If anyone could help me better understand the circuits I've seen I would be grateful. Thanks in advance for any guidance.
The project uses a NiMH battery of 4 AA cells in series to power a simple load of resistors to produce around 1.5 - 2 watts of heat. The heat will help prevent a hummingbird feeder from freezing in temperatures as low as -5°C. Here in Victoria, BC, and in other parts of the Pacific Northwest, the Anna's hummingbird doesn't migrate. Because they are at their limit in the winter nights, at the first light before sunrise they go to their usual feeders and recover from the torpor.
In the past years I had used 5 watt night lights and a layer of aluminum foil to keep the feeders from freezing, but where I live now there are no outdoor outlets. I would make an inductor to transfer electricity through the single-pane basement window, but I don't yet know how to do something like that. I plan to go to college here for an electrical engineering program, but in the mien time there are cold hummingbirds.
I figure with a modest amount of heat from resistors (designed to dissipate the heat) and a foil insulation wrap, I should get a few hours of operation on one set of batteries before I switch them for freshly charged ones.
Back to the task at hand, I need a way of preventing the batteries from over-discharging, as I don't want them to be damaged. I saw this thread but I am unsure which resistor values to change to set the cut-off points. I also saw this forum thread where an IC is mentioned, the MAX8211, however when I look at the spec sheet it looks like it will detect the voltage, and will include hysteresis, but I don't know how to use its output to disconnect the load. Does it simply send a digital signal to be used by a processor? I can't find what NMI means on the output.
If anyone could help me better understand the circuits I've seen I would be grateful. Thanks in advance for any guidance.