I need to sense amp draw across a large DC Motor 4" with Arduino uno

Other Hardware Motors, Mechanics, Power and CNC
1

I need to sense Amp draw across a large DC Motor and report it back via GSM. I need to know how to hook it up and program it. The GSM portion i have taken care of. I need a schematic.I will be trending the amp draw in a graph over time.

2

geostu34:
I need to sense Amp draw across a large DC Motor and report it back via GSM. I need to know how to hook it up and program it. The GSM portion i have taken care of. I need a schematic.I will be trending the amp draw in a graph over time.

The "standard" way would be to monitor the voltage across a low-value (0.1 ohm or less), high-wattage resistor; the voltage will be proportional to the current used (V=IR). Alternatively, there are also devices called "hall-effect current sensors" which are solid-state current monitors; depending on how much current you are monitoring, they range from "cheap" to somewhat expensive (considering what you get - ie, it will be an IC the size of a small relay, capable of monitoring 25 amps of current, costing $30.00+ each).

3

For large currents something more like 0.01 or 0.001 ohm is appropriate (you don't want fan cooling for the current sensor). Alternatively a Hall-effect current sensor.

Lots of nice modules out there for monitoring DC current BTW, such as: AttoPilot Voltage and Current Sense Breakout - 90A - SEN-09028 - SparkFun Electronics, SparkFun Current Sensor Breakout - ACS723 - SEN-13679 - SparkFun Electronics, http://www.skpang.co.uk/catalog/acs714-current-sensor-carrier-5-to-5a-p-707.html

4

MarkT:
For large currents something more like 0.01 or 0.001 ohm is appropriate (you don't want fan cooling for the current sensor). Alternatively a Hall-effect current sensor.

Well, the OP did leave off how much current was needed to be measured; 0.1 ohms would be fine for low currents, but smaller is definitely better...

MarkT:
Lots of nice modules out there for monitoring DC current BTW, such as: AttoPilot Voltage and Current Sense Breakout - 90A - SEN-09028 - SparkFun Electronics, SparkFun Current Sensor Breakout - ACS723 - SEN-13679 - SparkFun Electronics, http://www.skpang.co.uk/catalog/acs714-current-sensor-carrier-5-to-5a-p-707.html

The 90 amp breakout looks interesting; not a bad price, either - maybe the OP should tell us what his requirements are...?

:slight_smile: