Windy Nation 100 AMP DC Watt Meter - Manual (Page 8)

Watt Meter User Manual
Revision 1.0
4.1.2.1 Amps (A)
The Amps value displayed is the average current flowing through the meter’s black wire over the last screen
update interval.
The meter’s circuit operation draws a slight amount of current (~7 mA) from the SOURCE side. Being
hundreds of times less current than is drawn by typical loads, this slight additional current can be ignored
and the SOURCE’s current be considered equal to the LOAD’s current for most practical purposes. Amps
values are measured on the LOAD side. Currents over 50 Amps should be measured for reduced time due
to wire heating.
4.1.2.2 Volts (V)
The Volts value displayed is the average voltage over the last screen update interval. The Volts value is
measured on the SOURCE side.
4.1.2.3 Watts (W)
The value displayed is the average power delivered in Watts over the last screen update interval. Watt
values are measured on the LOAD side.
4.1.2.4 Cycle – Amp Hours (Ah)
The value displayed is the total charge in Amp-hours delivered to the LOAD since power was applied to the
meter. It is measured on the LOAD side. For accurate results, be careful not to interrupt the SOURCE
connection to the meter during a charge measurement.
4.1.2.5 Cycle – Watt Hours (Wh)
The value displayed is the total energy delivered to the LOAD in Watt-hours since power was applied to the
meter. It is measured on the LOAD side. For accurate results, be careful not to interrupt the SOURCE
connection to the meter during an energy measurement.
4.1.2.6 Cycle – Peak Amps (Ap)
The displayed Peak Amps value (Ap) is the maximum current drawn on the LOAD side, since the startup
screen ended.
4.1.2.7 Cycle – Minimum Volts (Vm)
The displayed Minimum Volts value (Vm) is the minimum voltage (or “sag”) measured on the SOURCE side,
since the startup screen ended.
4.1.2.8 Cycle – Peak Watts (Wp)
The displayed Peak Watts value (Wp) is the maximum power drawn on the LOAD side, since the startup
screen ended.
4.2 R ESETTING T HE M ETER
Resetting your meter will clear all accumulated readings including Ah, Wh, peak current, etc. Your meter can
be reset to zero in one of two ways:
1) Completely remove all voltage from the meter; Source's Red AND/OR Auxiliary Connector Pin 2
2) Briefly connect the Auxiliary Connector's pin 3 to zero Volts. E.g. pin 1 or the meter's black wire.
a) Note that the meter will be held in reset and not function if pin 3 is continuously connected.
Pin 1 is the pin farthest from the meter’s SOURCE wires and Pin 3 is nearest the SOURCE wires.
5 APPLICATION
You can think of the meter like a set of jumper wires. Connect it in the same way and you can measure what
the jumper wires are connected to. Like Jumper wires, the meter is essentially a direct connection between
correspondingly colored SOURCE and LOAD wires, i.e. both the “SOURCE” and “LOAD” leads of the meter
are electrically “hot” when a battery is connected to either side.
5.1 M AXIMUM C URRENT C APACITY
Current flowing through the watt meter’s wires generates heat due to the resistances of the wires and of the
precision internal current shunt used for current measurements. Though very low ( ~ 0.004 Ohms in 14 gage
wires and 0.001 Ohms in shunt), these resistances are finite and at high currents the heat generated
becomes noticeable. This is because heat is created with the "square" of the current.
I.E.: heating power (W) = current
2
(A) × resistance (Ohms)
Page 8 of 11 Windy Nation 04/19/2012