Electric Bike Connections for the "Watt's Up" Meter
Example electric bike connections are shown in the diagrams below.
Four Wire Connection (easy to understand)
The "jumper cable" hookup. While easy to use, this approach forces the use of heavy gage wire for the plus lead and increases power dissipation in the meter. It also slightly decreases voltage accuracy at higher currents due to additional voltage drop across the plus lead. The drop is ~0.01 V per 12 A compared to the voltage at the meters source lead tips.
Three Wire Connection (better performance, less wire)
The three Wire hookup has several benefits. This arrangement requires only two heavy gage wires to carry the negative lead current and so is better for remote testing and monitoring. The third, plus, wire can be lighter gage (e.g. 20 gage or heavier) as it only carries the small current required to run the meter itself.
The three wire hookup also allows higher current operation as the heat from power dissipated by high current in the plus wire is no longer present.
A battery or other voltage limiting device must be connected between the meter's red and black leads anytime the load is connected or disconnected. The battery prevents inductive loads causing damage to the meter.
Our Meter Links page has a handy wire resistance and voltage drop calculator.
Many other meter uses and arrangements are possible.
Please see the meter's User's Manual for more details and safety precautions.
Diagrams show energy flowing from left to right
Electric Bike Connections