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I need a circuit to indicate level of 12V battery

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moonstreat

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I need a circuit that would indicate when my battery is with:
-12v;
-11v;
-10v;

how can I apply this to indicate the level of voltage of my battery?
 
LM3914 with LED bargraph display? or do you want fewer LEDs? Voltage Reference driving three or four LM339 comparators, but that is more complicated than the LM3914 would be.
 
Here is one that I developed a few years ago. It is for a lead acid battery
 

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You don't have to use all of the LED outputs, of the LM3914, you only need to use the last three if you like.

Is this for a car battery?

If so, i think you might need to be able to be able to indicate if the battery is over 12V, perhaps up to 15V to show whether it's charging.
 
my battery is 12V 7mA

When the battery:
- A maximum load (12V) I wanted the green light;
- 1V unload when it came down to the 11v yellow LED light;
- When the battery was 10V for the red LED would light up!

this is what I need, serves to indicate the level of the battery of my car
 
What do you mean, your battery is 12V 7mA?

Batteries aren't measured ain mA but mAh or Ah and a car battery will be much larger than 7mAh.
 
Must be a rather small car if it only has a 7AH battery. Sounds more like a motorcycle.
 
What do you mean, your battery is 12V 7mA?

Batteries aren't measured ain mA but mAh or Ah and a car battery will be much larger than 7mAh.

hi hero,
You are the only poster who has used the 'car battery' concept.;)
 
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Yes, I don't know where I got that from.

Still I haven't seen a 7mAh 12V battery before, 7Ah yes.

Anyway, use an LM3914 or LM339 as mentioned before.
 
how do the voltage divider with the LM339?

I want the LED turn red when the battery is 10V
turn yellow when you have to 11V
and green is connected when the battery is at 12V

you can do this circuit?
 
Hi moonstreat,

you might want to go with k7elp60's suggested circuit.

Here is small PCB-design, single sided with nine wire jumps.

Board size is 1.85X1.75".
 

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Is this 8 wire jumps? I don't find JP7.

Nothing is more difficult for a math professor to count from zero to any number.

I'm far away from that.

Please forgive my wrong counting. :D

Anyway, all necessary jumps are contained in the PCB design. :)

Regards

Boncuk
 
Is this 8 wire jumps? I don't find JP7.

Sorry AlainB,

number 7 doesn't excist for my type of counting.

It has had a bad influence on my life. :(

My father died on the seventh day in May 1943 at seven o'clock in the morning, when I was seven months old.

So it's easy to explain why I try to avoid count "7".

Boncuk
 
Gentlemen thanks for your PC board layout, it is much more professional than mine. I built a number to these devices and enclosed them in a small plastic box. Original design used a bridge rectifier as the input and as a result it was not polarity sensitive.
I usually etch my own boards. I print the layout on a transparency and use positive sensitized boards. Anyway here is the single sided layout. The two large circle's with an inner circle were for placing the circuit board on the mounting supports in the enclosure. The enclosure used was a PACTEC model JM12-IE
 

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