Circuit Battery Level Indicator
This
circuit uses a LM339, a quad comparator. LM339 can work on single or dual supplies, it has a open collector output that can drive 15mA, low power consumption.
The circuit is an untested design but it should work. I did it as many searches were made in my webpages with these keywords.
R16 a 5W ceramic wire wound bleeder or dummy load. R15 is a part of an attenuator for obtaining ranges. D2 is a protection clamp diode. R10-D1 forms the 5V reference for comparators. Then an attenuator obtains 1.2, 1.4, 1.6, 1.8 V steps for each comparator. This circuit is similar to
Audio Level meter or VU meter circuit.
There are many better circuits in the various circuit archives i have linked on the front page, you just have to look around. When you measure the open circuit voltage of a battery with a high impedance DMM (10M), the value may be a bit misleading.
Apply a dummy load to bleed the battery a bit so that proper readings can be taken on Load. The load below is a 100 ohms wire-wound fusible ceramic resistor which will heat a bit when you test 12V
batteries.