1x Lion low voltage monitor for low power output (<100mA)

1 post / 0 new
JackCY
JackCY's picture
Offline
Last seen: 7 years 8 months ago
Joined: 12/28/2012 - 16:30
Posts: 588
Location: Czech
1x Lion low voltage monitor for low power output (<100mA)

I’m looking for a simple, cheap voltage monitor to make from parts. I doubt they sell anything anywhere except the Lipo multicell monitors.

The output of the device is few LEDs, <100mA.
Input is unprotected 1× 18650.

I would like to have an indication of low voltage = below 3V.
In best case an extra LED would light up to signal low voltage.

Acceptable options are also: main output shuts down and an extra LED lights up. Or in the worst case, just the main output shuts down if below 3V.

Budget as low as possible.

I’ve looked at zener diodes and TL431 but didn’t like them, got confused.
I didn’t like that they drained the input all the time whether in use or not.
And that they had a big drop out.
The LEDs run directly on the 18650 so it’s best for any drop of voltage to be minimal.
Also why an indicator is sufficient.

Something like an 18650 protection PCB from DX… well, I don’t think they are reliable, more like a thing of last resort to not discharge under 2.5V.

Thanks.