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i need the circuit design of 12 VDC bateery meter URGENT cause i want to use it in a robot to detect the battery charge easly when the battery connected to the robot
If the battery is lead-acid then a voltmeter won't tell you much:
1) It will be about 13.8V while still charging but it is fully charged. It will be a little less while still charging but it is not fully charged.
2) The voltage will drop when the battery is heavily loaded, whether it has a full charge or whether it has only a partial charge.
3) The voltage will be about the same without a load whether the battery is fully charged or only partially charged.
4) The voltage will be low when it is heavily loaded when the battery is nearly dead. But you would know that.
Just run the battery through a resistive divider to the robot's microcontroller and compare it to the regulated power supply (which should be pretty much constant whether the battery is high or low since if it's too low, the robot shuts off anyways).
YOu will have to take into account the battery type and study the characteristics.
thanx men but wt i want u to know that i'm making a small robotics cources in my college & not all the students will understand this so i want to make simple circuit toa battery detector and give it to my students , because if the battery empty this student will find any indecator says that the battery empty to recharge it again
A voltmeter will show a different voltage when the robot is doing different things, even when the battery is fully charged. You don't need a voltmeter to tell you that when the robot runs slow or stops, then the battery is empty.
I am not sure how accurate measuring a battery voltage under load to figure out capacity remaining. (All battery checkers I have seen seem to do this, but the battery disconnected from the system and is only plugged into the battery checker and is not under a load).
If you want a simple voltmeter to measure the battery voltage (or whatever else), maybe use a voltage regulator and run the regulated voltage through a resistisve dividers with several resistors to give several different reference voltages. Use these voltages as the reference for some op-amp comparators driving LEDs. Then run the battery voltage through a resistive divder that will reduce the full battery voltage so that it is equal to the voltage regulator output. Then feed this reduced battery voltage to the op-amp comparators.
This should make a kind of "LED bar voltmeter" which I guess could be used as a rough battery capacity indicator.
i saw a car with a remote control its for my brother there are 2 leds in the ca the green led indecates that the battery full then the red led indecated that the battery will be empty soon
Didn't the car run slowly or stop when the red LED lighted?
Did it have the same kind of battery as in your robot?
You could make a green/red battery voltage indicator. It would be red every time the robot accellerates or works hard even if the battery is fully charged. It would be green when it is resting even if the battery is nearly dead.
You might be able to adjust it so it doesn't give too many false indications.
THey have this on RC airplanes and other things so that you know when the transmitter is getting too low on power so you can land the plane.
It's basically what I described above, except with just one resistor divider and one comparator, and one LED. THe voltage from the resistor divider should be the voltage when the battery is almost dead (after it has been reduced by another resistor divider).
einSTein2006,
We appreciate your help, but please don't take circuits from others then call them your own. This is known as pagarism which is actually illegal.
Now do you want me to report you to the website owner?
**broken link removed**
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