I want to build a battery level indicator circuit for a 12 V sealed lead acid battery.
The battery indicator circuit will have two functions:
- It will power 4 LEDs to show the level of the battery
- At the lowest level it should disconnect the load from the battery to prevent deep discharging. To achieve this, I'm considering using a MOSFET (IRLML6244) as a switch. (comments on this approach welcome)
So far I've seen predominately two approaches to achieve this. The first method uses zener diodes and transistors to switch the LEDs as shown here
The other method uses op-amps as comparators to switch the LEDs as used here
I can't really see a clear advantage of the one over the other. I think the components costs will be roughly similar, but maybe a bit more soldering when using the zener approach. Keeping in mind that I also want to switch the MOSFET, which of these methods (if any) is the recommended method to use in my battery indicator circuit?
Not sure if it makes a difference, but my load won't draw more than 1A.