So i've set up a makeshift battery monitor to show when my batteries are full, when charging. I set up the circuit using the instructions from http://www.reuk.co.uk/Make-a-Simple-Battery-Status-Monitor.htm The circuit with measured voltages is as follows:
The article implies that the LED will only light if the voltage is higher than the zener voltage, but looking at the circuit it looks as if the amperage, and not the voltage, will vary. the voltage across the zener diode will always be at the rated 6.2 V, but the current will change depending on the batteries voltage.
I guess my real question is, will the strength of the light in the diode represent the voltage of the batteries?
the strength of the light will depend on the current to it, which increases when the battery draws less current
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