Make a measurement. See the Science Buddies reference How to Use a Multimeter if you need help.
Connect the probes (also called leads) of the multimeter to the two ends of the battery by placing one probe tip on aluminum foil strip at the bottom of the stack and the other to the nickel on the top of the stack. Figure 6 shows the setup.
Measure the voltage produced by your battery: set the multimeter to measure DC voltage (direct current) and select volts (V) as shown in Figure 6. Push down on the multimeter probe tips to make good electrical contact. Write down the your measured value (number only, not the sign) in the table like Table 1. Note positive or negative measured values are both fine. You are interested in the number value without the sign (see also step d.) Consult the Frequently Asked Questions for more advice.