Battery Monitors

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watzmann

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Hi All ,

i'm looking for a good battery monitor schematic for my robot, i have a abattery Lead Acid 12 volt.

have anybody built such project ?, i tried one before but it doesn't work properly.


Thank you ,

M.Farag
 
hi,

This device is made as a battery status monitor.
 
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The LM10 is an accurate 200mV reference with an opamp to amplify it and another opamp that is used as a comparator, in an 8-pins DIL case.
It can be used as an over-voltage or under-voltage sensor.
 
Most chips are very inexpensive.
Postage to Egypt might cost a fortune.
 
o.k , now i have searched for the chip MAX 8211 in Egypt but i can't find it ,

have u other suggestions for building battery monitor? ......using PIC is more easier as for me .
 
watzmann said:
o.k , now i have searched for the chip MAX 8211 in Egypt but i can't find it ,

have u other suggestions for building battery monitor? ......using PIC is more easier as for me .
hi,
Which PIC do you have?
 
actually the battery monitor is my main problem now , imagine that you have a robot and you don't know when will the battery will be empty,
 
watzmann said:
actually the battery monitor is my main problem now , imagine that you have a robot and you don't know when will the battery will be empty,

hi,
If your robot is controlled by a 16F877, this PIC has internal 10 bit analog to digital convertors. It would be very easy to monitor the battery voltage, use a resitive potential divider to keep the maximum voltage into the ADC <=+5V.

Is this what you mean?
 
watzmann said:
actually the battery monitor is my main problem now , imagine that you have a robot and you don't know when will the battery will be empty,

Some PICs have Low/High voltage detects now.
The 16F917 and 18F4620 (an excellent chip for a robot) have this module.
 
i have thought of the sugesstion of using the internal A/D converter to read the volts , and i think i can do that to read volts up to 5 Volts , using the 7805L.....but i need to measure more volts than 5 volts , 5 is so low......i think i need to measure up to 12 Volts.

how to do that ............ i'm sorry but i'm still beginner
 

Hi,
You use a resistor voltage divider.
Example in the gif.

Dont go much higher in the resistance values, as the PIC's ADC input expects a source resistance of <=10K0

Always calculate the resistors so that Vout is <=+5V [ADC input] using the highest expected value for Vin.

The values shown are for a Vin max of +12V.
 
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