Battery monitor question

[YoTech]

Hello eveybody! My question is simple. I am making a battery monitor, which will light a LED if the battery is at 10.5V, 13V and charged at 14.2V.

My idea is to put a zener diode after the battery which should break through when the battery is charged to the voltage it needs. After the zener diode there is a current limiting resistor, after the resistor there is a second zener at 5,6V, after the second zener there is another current limiting resistor and the LED is last. I intend to put 3 such zeners and LEDs.

What bothers me is that there will be a charger connected to the battery, will the battery limit the voltage to whatever its charged or will the zeners just break through if the charger is connected?

I will add a picture of the circuit later.

 

[ramussons]

Waiting for the schematic......
Meanwhile, if the Zeners are in series, why do you need a current limiting resistor for each zener?

Why not use a LM 3914? It's much simpler and flexible.

https://www.electronicshub.org/battery-level-indicator/

 

[Bluejets]

There is a fairly simple old circuit on the web for a battery volt monitor based on the fact that red, green and yellow leds have different voltage drop.

Found it........
https://archive.org/details/ElectronicsTodayInternational

Look at last book called Electronics Today Projects book N0.2-1981-01 and look at pages 44 to 45.

 

[YoTech]

Here is the circuit, I will post the components used as soon as I can.

 

[YoTech]

Waiting for the schematic......
Meanwhile, if the Zeners are in series, why do you need a current limiting resistor for each zener?

Why not use a LM 3914? It's much simpler and flexible.

https://www.electronicshub.org/battery-level-indicator/

Is it not a display driver?

 

[YoTech]

I will add a bit more explanations.

I have a charger already its ABC-1220D, at 14.7V 20A. I need to monitor the battery for faults meaning how fast it charges, and how discharged it is at the moment,

 

[BobK]

Zener diodes will not give you sharp results at discriminating voltages. You want to use comparators, which will allow a binary result based on an exact voltage.

Bob

 

[YoTech]

You mean it will work even while the battery is charging (the battery will hold the voltage at whatever level its charged to?), but the zener diodes will not hold the voltage stabely at the chosen value?

The problem I met with the comparators is that I have to power them again and that I have to give them a reference value (U+) or (U-) again with zener diodes? If I put a 3.3V power supply on the comparators will it work? Or should I put a 5V power supply and hope to get out 3.3V?

If I have to put on the comparator 14V at (U-), shouldnt I do it with zener diodes again?

 

[YoTech]

Here is the comparator circuit. I havent added all comparators. Also I am guessing there will be no problem with the LED before the fuse, which is used to signal if the battery has been plugged in in reverse.

 

[YoTech]

My assignment just changed . Thank you for you help until now. If you still want to help here is the final assignment:

2 batteries by 12 volts will be charged separately while in a battery pack box, and will be used for the load together.

 

[YoTech]

I think this one is good? I will use 1% SMD resistors in order to increase the accuracy.

Any help is appreciated!

 

[YoTech]

Sorry for the multiple post. This is the latest circuit, I ask will the diode right after the battery be light, when the battery pack is connected in reverse (+ and - switched)?

My idea is to monitor the voltage of the whole pack and then I will make something for monitoring only 1 of the batteries in order to check the charge discharge time of every battery (whole pack voltage minus 1 battery voltage equals second battery voltage).