With a knowledge of how to connect cells in parallel and series, we can figure out how to arrange batteries to deliver a desired voltage, and in some cases, make them last longer.

Here is an example question. We’re asked to use wires to connect these 12 volt batteries in such a way that we will get 36 volts from the arrangement. + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement.

They must all be connected in series for the three 12 volts to add up to 36 volts. Series is positive to negative to positive to negative etc. + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement. They must all be connected in series for their voltages to add up to 36 volts.

We’ll connect a red wire to the positive terminal on this battery, + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement. They must all be connected in series for their voltages to add up to 36 volts.

And other wire from the negative terminal of this battery to the positive terminal of the next battery + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement. They must all be connected in series for their voltages to add up to 36 volts.

Then another wire from the negative of this battery to the positive of the third battery + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement. They must all be connected in series for their voltages to add up to 36 volts.

And finally, a black wire from the negative terminal of the third battery. + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement. They must all be connected in series for their voltages to add up to 36 volts.

A voltmeter is connected so that its positive terminal is attached to the red wire and its negative terminal is attached to the black wire. In electrical circuits, red generally stands for positive and black for negative. + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement. They must all be connected in series for their voltages to add up to 36 volts. V + –

The reading on the voltmeter will be 36 volts + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 36 volts from the arrangement. They must all be connected in series for their voltages to add up to 36 volts. 36 V + –

We’ll draw a schematic diagram to represent this arrangement of three 12 volt batteries V V

This corresponds to the first battery V V

You can see that the positive terminal of the first battery is connected to the voltmeter in both of these diagrams V V

And the negative terminal of the first battery is connected to the positive terminal of the second battery in both diagrams V V

This corresponds to the second battery 12.0 V V

The positive terminal of this battery is connected to the negative terminal of the first battery in both diagrams 12.0 V V

The negative terminal of the second battery is connected to the positive terminal of the third battery in both diagrams 12.0 V V

And this corresponds to the battery on the right V V

The positive terminal of this battery is connected to the negative terminal of the second battery in both diagrams, 12.0 V V

And the negative terminal of this battery is connected to the voltmeter in both diagrams V V

And, of course, the voltmeter in the schematic diagram will read 36 volts V V 36 V

Here is another example question. We’re asked to use wires to connect these 12 volt batteries in such a way that we will get 24 volts from the arrangement and have the batteries last as long as we can. + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can.

We’ll start by attaching a red wire to this terminal + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can.

We’ll put the first two batteries in parallel. Positive to positive + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can.

And negative to negative. Putting two of the batteries in parallel will help to make them last longer. In order to get 24 volts, we must put the third battery in series… + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can.

We’ll connect the negative terminal of the second battery to the positive terminal of the third battery… + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can.

And then connect a black wire to the negative terminal of this battery. + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can.

Again, we connect a voltmeter to the wires like this… + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can. V + –

And the voltmeter will read 24 volts. + – 12 volts + – + – Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can. 24 V + –

The schematic diagram for this set-up would look like this Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

If you study this, you will see that this part of the schematic represents the first two batteries in parallel with each other, positive to positive and negative to negative. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

Two 12 volt batteries in parallel will deliver 12 volts. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

This represents the third battery, the one in series with the other two. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

We see that the positive terminal of the first battery is connected to the voltmeter in both diagrams. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

And to the positive terminal of the second battery in both diagrams Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

The negative terminal of the first battery is connected to the negative terminal of the second battery in both diagrams. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

And the positive terminal of the second battery is connected to the positive terminal of the first battery, (click) and to the voltmeter in both diagrams Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

The negative terminal of the second battery is connected to the negative terminal of the first battery in both diagrams Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

And the negative terminal of the second battery is connected to the positive terminal of the third battery in both diagrams. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

The positive terminal of the third battery is attached to the negative terminal of the second battery in both diagrams Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

And the negative terminal of this battery is attached to the voltmeter in both diagrams. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

This 12 volt arrangement of two batteries in parallel, Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

And this 12 volt battery in series with it, Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V

will provide a final voltage of 24 volts. Use wires to connect these three 12 volt batteries in such as way as to get 24 volts from the arrangement, and have the batteries last as long as you can V V 24 V