DC low voltage indicator for 7.4 volt battery

148

04:32:50

DC low voltage indicator for 7.4 volt battery

published 10 years ago

hylco

10 years ago

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hylco

10 years ago

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Sunburst275

10 years ago

How does this work?

wyoelk

10 years ago

The only problem is if volts drop below another level you have no indicator. This is just a mid range system

JaredNew

10 years ago

Wyoelk that is correct. I have it on a bread board right now and the LED is still light at 5 volts and turns on at 7.1 volts. hopefully someone would not let a 7.4 volt (8.4 volt on full charge) get down to less than 5 volts. Whatever that battery is powering would no longer work at that voltage anyways.

JaredNew

10 years ago

Sunburst275 When the LED is placed between the two Zener diodes, the LED will conduct current when the difference between the two Zener diodes is greater than the Zener forward bias voltage. Here is the equation for this circuit to figure out what voltage of diodes you need for it to illuminate at a specific voltage and with the measured forward voltage of the LED used. I will use the values that are used in this circuit as reference; IF Vbat (7.1) < Vz1 (4.7) + Vz2 (5.6) – 3.2 (Blue LED forward bias)

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