Full Charge LED Indicator?

Joined
Jun 14, 2016
Messages
14
Likes
33
Does anyone know how to build a circuit that turns an LED on when the voltage source goes above a certain voltage without using a zener diode? I've tried implementing a few ideas but they don't work as well as I want them to.
 
Joined
Jun 14, 2016
Messages
14
Likes
33
I'm not using a smart charger. I'm using an Adafruit Powerboost 1000c for a raspberry pi portable, but the LEDs don't light up when I want them to. I want to make a separate low battery and full charge indicator. I've got the low battery indicator working, and now I just need the full charge indicator to work.
 

JacksonS

.
.
.
Joined
Feb 17, 2016
Messages
301
Likes
576
Location
Boston, MA
Portables
6
I'm sure a microcontroller would do it, but as for making a transistor-based circuit, I don't know.
 

ShockSlayer

the real
.
.
Joined
Jan 16, 2016
Messages
1,512
Likes
3,940
Location
standing up
Portables
please do not ask!!!! I will NOT respond
Daftmike's 5 transistor circuit should work. You'll be using it in reverse, but all you have to do is calibrate it to only turn green when the battery's voltage is at full charge.

All it does is set the voltage threshold; whether it's above it or below it is what determines the lit LED. Make sure you get a good trimmer potentiometer so you can be precise.
 
Top