battery cell monitoring

[M.Imran Ali]

Hi
I have 4 battery connected in series to give 48 v. I am to monitor voltage of each cell using micro controller. I am thing to use differential amplifier to give exact reading of cells. I have to monitor all cells . Am i right ?
Plse discuss some other process that is better than it?
Can i change my ground level for each measurement an other process came in mind that i change ground reference on measuring each cell? like 46 to 48v cell i take 46 as reference and measure 48v with adc? Is it possible or i have to go for common ground and differential amplifier? Pls suggest me Dif. Amp cct if you have?
Thanx to all in advance

Regard
m.Imran Ali

 

[Genovator]

See this link... Go with the calculations... See if it helps..
http://picprojects.org.uk/projects/vmon/

Voltage dividers would be best to measure high voltages...

 

[M.Imran Ali]

Sir Genovator there are 24 cells each of 2 V . I am to monitor each cell of battery?

 

[tpetar]

Lets say as one of solution, I think that can do the job. You can measure voltage in cycles starting from first, then second, third,.... with voltage difference before and after of measuring each cell you get what is voltage of particular cells (voltage of last measured cell). Measuring cycles repeating from first cell from begining to last cell in serie, then start new measuring cycle, all over again.

 

[Genovator]

For what purpose you want to measure voltage????
Is it compulsory for you to keep an eye on every cell's voltage, or you just want to know the total voltage you have at a particular time to run something????

You assembled 4 cells in a series to get 48V. Now consider this set-up as a single battery. If you are running something with this, and want to know when the battery runs out, you no need to measure voltages of each cells, as each 24 cells are connected in series. You need to monitor the total voltage of that set-up.

 

[tpetar]

I think individual cell monitoring is very usefull. Cells are similar but different in many aspects as aging, malfunction,.... there is no need to replace whole battery pack because one bad cell.

 

[Genovator]

Yes, that's right. Individual cell monitoring is needed for older/used batteries. They shows faults with time. This thing can be neglected for new ones, but not for longer time. When batteries health is a concern, each cells need to be monitored.
Otherwise, for simplicity, I think only total voltage monitoring will do. :smile: