johnsenior
New Member
I want to build a LED ammeter to supplement the existing analog (needle style) ammeter in the power supply for an Electric Vehicle. I plan to use the typical voltmeter circuit based on a lm3914 ten segment LED driver, and just tap into the sensing leads to the existing ammeter. The 12V auxiliary circuit will be used to power the lm3914. (The electric motor runs on 144V from 24 six volt batteries).
However, the shunt built into the EV power supply to feed the ammeter only provides 50 mV drop at full power (50 amps). I assume this is less than is needed to drive the lm3914 to full scale. Can anybody suggest a simple addition to the circuit to boost the voltage enough to use the lm3914 IC? Or is there a better approach?
However, the shunt built into the EV power supply to feed the ammeter only provides 50 mV drop at full power (50 amps). I assume this is less than is needed to drive the lm3914 to full scale. Can anybody suggest a simple addition to the circuit to boost the voltage enough to use the lm3914 IC? Or is there a better approach?