Go Down

Topic: Voltage Divider Battery Monitor (Read 1 time) previous topic - next topic

VizBiz

Hi all.

44v battery pack that I want to monitor on an analog pin.

Thinking of doing this (with a 5.1 Z Diode) connected to stop any nasty things....

http://www.electronics2000.co.uk/calc/potential-divider-calculator.php

Thinking r1=18k and r2=2k

That will be 5v and 50v....

Are there better options?

Thought?

Thanks

jackrae

That'll work OK but at what voltage is your 44volt battery charged.  If it's a rechargeable battery rated at 44 volts then the charge voltage could be as high as 60.  As to the zener diode for protection, you could eliminate it by placing a resistor of say 10k connecting the junction of R1/R2 and your analogue input.  This resistor will limit the input current and so prevent damage.

Erdin

I would select higher values for the resistors.
The zener is not needed with the higher values and with the higher values I would omit extra protection resistor as jacrae wrote.

The impedance of the voltage divider for the analog input should be 10k or less for a good ADC value.

So I would choose 10k for R2 and 120k for R1.
The impedance would be 10k parallel 150k which is near 10k.

The measures voltage is 0 .. 65V. The accuracy would be 100mV or 200mV (63mV in theory).

In case R2 doesn't make contact, the current into the analog port would be 44-5 / 120k => 0.3mA
I think the analog input is not destroyed by that (I hope).

Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy