Saturday, March 30, 2013


With the battery voltage meter part of the instrumentation project finished. It was time to move on to the important current meter part of the project. BIANKA already had a Xantrex XBM battery monitor but, to see it required that I move away from the helm and lift a cockpit hatch and bend down to see it. It was awkward and inconvenient to look at while underway.

I went looking for another meter that could measure the current being drawn from or charging the battery bank. But, the catch was I did not want to have to put in another shunt for measuring  current in the battery circuit like the XBM battery monitor already used. I wanted to keep any extra connections to a minimum. To do that I needed to use a hall effect type of current meter.  It determines a current value by measuring the magnetic flux around a piece of wire with current flowing through it. I found exactly what I needed with a company called Devicecraft. They had a hall effect current meter with a transducer that would fit the 2 AWG wires that connect to  BIANKA's 48 volt electric propulsion battery bank.

The hook up is farely simple.

The display required a supply voltage and three wires that go to the hall effect transducer.  I needed to run the transducer wires about eight feet and used some   Twisted Servo Hookup Wire,   normally used in things like model cars and planes:

Like I did for some of the wires for the battery voltage meters part of this project I enclosed the transducer wires in a  Techflex General Purpose 1/4-inch Braided Cable Sleeve.  This was to keep the wires together and also protect them from chafing.

The 100 amp Hall effect sensor will fit over the 2 AWG cable that is used in the my electric propulsion system but, would not fit over the existing lug. So I needed cut the existing battery cable. I used a ratcheting wire cutter like a Klein ratcheting cable cutter which cuts heavy duty battery cable easily:

and makes a nice flush cut:

I took the opportunity to trim some other 2 AWG  battery interconnections that were a little too long from my initial electric propulsion installation five years ago too.  The Hall Effect transducer has a polarity in terms of it's display. That is if you a drawing current from the battery the display should show a negative sign in the display. Likewise when charging the battery it is useful to see the current flow as positive (no minus sign) on the digital display.  In order to make sure I got the polarity right I used some of the trimmed battery cables and a jumper to check the polarity of the meter.

Once I had established the proper orientation for the sensor I put it on the battery cable and crimped a new lug on the end and reconnected it to the battery. I then ran the sensor wires up through the cockpit wire conduit I made and into the helm area using one of the  Fiberglass Wire Pull Rods    I carry on board:

It was then just a matter of hooking up the sensor and power wires to the current display and the instrumentation project was finished:

I mounted it the box temporarily at the helm and used it on my fall cruise up the Hudson River and back. I still need to make a permanent platform for the box at the helm location but, that is a project for another day.

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