listiak@eniac.seas.upenn.edu (Jeffrey Listiak ) (01/30/91)
Hello. I am developing some sensors for use in an electric vehicle. The
batteries for this vehicle are twelve 12V batteries in series and are
occasionally required to deliver up to around 50A. I need to develop a
system to record how much current has flown over time both into and out of
the batteries. A one milliohm current shunt is in series with the batteries
and the load. I am interested in any ideas that might relate to this task.
I also would like to know of any commercially availible complete DC amp-hour
counters and the appropriate addresses/phone numbers of the suppliers.
My initial idea is to use a voltage to frequency converter such as the AD654
to convert the millivolt signal (1mv = 1A in the wire) to a pulse train
which is fed into a Radio Shack LCD counting module. Higher currents in the
wire would cause higher voltages and the counter would count faster. The
total count would then represent the total energy flow. Any advice as to
alternative designs, short-comings of this design, or advice about the AD654
would be greatly appreciated.
Additionally, I need to know where I can obtain digital panel voltmeters or
ammeters at relatively low cost. I need some that can handle up to 200VDC,
15VDC, and 100 mVDC.
Please send responses to listiak@eniac.seas.upenn.edu
Thank you for your help!
Jeff Listiak
Electrical Engineering Department
University of Pennsylvania