Battery Monitors

[watzmann]

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

 

[ericgibbs]

hi,

This device is made as a battery status monitor.

 

[watzmann]

it looks very nice .... check this

https://www.electro-tech-online.com/custompdfs/2007/09/botanicalls_energy_finalpresentation.pdf

 

[audioguru]

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.

 

[watzmann]

where is the best place online to order chips with affordable prices?

 

[audioguru]

Most chips are very inexpensive.
Postage to Egypt might cost a fortune.

 

[watzmann]

that's right

 

[watzmann]

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 .

 

[ericgibbs]

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?

 

[watzmann]

pic 16f877

 

[watzmann]

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,

 

[ericgibbs]

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]

check this schematic


https://www.qsl.net/yo5ofh/pic/battery monitor.htm

 

[ericgibbs]

check this schematic


https://www.qsl.net/yo5ofh/pic/battery monitor.htm

hi,
Have looked at the link, its using a PIC, so why dont you use an ADC input on your 16F877 to do the same job.

Unless you want a battery monitor/indicator external to the robot, if so, then a DVM would do the same job.

Do you follow my suggestion?

 

[blueroomelectronics]

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.

 

[watzmann]

yes follow your suggestions

 

[watzmann]

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

 

[ericgibbs]

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.