I was experimenting on the work bench today with a SSC P7, trying to dial in the resistor values needed to make a simple driver board. The dual 1400ma stack I make is too difficult for the average user and I need something easier to assemble.

I started with a freshly charged 4.2 volt - 4 x 18650 protected cell battery pack.

I set up two multimeters for measurements.

One is in line measuring the current flow on the way to the P7.

The other one is measuring the voltage drop across the test resistor.

I had a bag of .68 ohm Vishay resistors and so I started soldering them together in parallel to reduce the resistance and then take a new measurement. I also used a couple 1 ohm resistors to get 1 and .5 ohms.

The spreadsheet below shows the resistor value in ohms

The voltage drop across the resistor in volts

The current flowing in the circuit in amps

The wattage column was just a calculation of Voltage x current

Note that when I did a quick direct drive/no resistor check, I read 3.4 amps.

<TABLE dir=ltr border=1 cellSpacing=0 borderColor=#000000 cellPadding=2 width=281><TBODY><TR><TD height=16 colSpan=4></TD></TR><TR><TD height=16 width="26%">Battery pack = 4 x 18650 = 4.2 volts DC</TD><TD height=16 width="24%">Resistor</TD><TD height=16 width="26%">Voltage</TD><TD height=16 width="25%">Current</TD></TR><TR><TD height=16 width="26%">Wattage1.0000</TD><TD height=16 width="24%">0.890</TD><TD height=16 width="26%">0.88</TD><TD height=16 width="25%">0.7796</TD></TR><TR><TD height=16 width="26%">0.7000</TD><TD height=16 width="24%">0.820</TD><TD height=16 width="26%">1.00</TD><TD height=16 width="25%">0.8200</TD></TR><TR><TD height=16 width="26%">0.6800</TD><TD height=16 width="24%">0.775</TD><TD height=16 width="26%">1.14</TD><TD height=16 width="25%">0.8835</TD></TR><TR><TD height=16 width="26%">0.5000</TD><TD height=16 width="24%">0.685</TD><TD height=16 width="26%">1.30</TD><TD height=16 width="25%">0.8905</TD></TR><TR><TD height=16 width="26%">0.3400</TD><TD height=16 width="24%">0.575</TD><TD height=16 width="26%">1.71</TD><TD height=16 width="25%">0.9833</TD></TR><TR><TD height=16 width="26%">0.2267</TD><TD height=16 width="24%">0.466</TD><TD height=16 width="26%">2.06</TD><TD height=16 width="25%">0.9600</TD></TR><TR><TD height=16 width="26%">0.1700</TD><TD height=16 width="24%">0.391</TD><TD height=16 width="26%">2.31</TD><TD height=16 width="25%">0.9032</TD></TR><TR><TD height=16 width="26%">0.1360</TD><TD height=16 width="24%">0.337</TD><TD height=16 width="26%">2.48</TD><TD height=16 width="25%">0.8358</TD></TR><TR><TD height=16 width="26%">0.1145</TD><TD height=16 width="24%">0.293</TD><TD height=16 width="26%">2.62</TD><TD height=16 width="25%">0.7677</TD></TR><TR><TD height=16 width="26%">0.0971</TD><TD height=16 width="24%">0.265</TD><TD height=16 width="26%">2.73</TD><TD height=16 width="25%">0.7235</TD></TR><TR><TD height=16 width="26%">

</TD><TD height=16 width="24%">

</TD><TD height=16 width="26%">

</TD><TD height=16 width="25%">

</TD></TR><TR><TD height=16 width="26%">0.0000</TD><TD height=16 width="24%">0.000</TD><TD height=16 width="26%">3.40</TD><TD height=16 width="25%">0.0000</TD></TR></TBODY></TABLE>

Here's the diagram of how I set up the cicuit.