# AA primary batteries in series and parallel configuration

As shown in above image we are using two AA alkaline batteries in series and two in parallel.

Each battery is 1.5 V and 2700 mAh in capacity. So in above configuration total battery voltage would be 3 V and capacity would be 5400 mAh.

So my question is can we connect without any issues as shown in above configuration of two batteries in series and two in parallel?

• Putting voltage sources in parallel is forbidden. Jul 9, 2021 at 16:22
• @MissMulan Is it? What forbids putting voltage sources in parallel? Boats and motor vehicles put batteries in parallel all the time and yet these work fine. Jul 9, 2021 at 16:28
• KVL forbids putting 2 nvoltage sources in parallel Jul 9, 2021 at 16:30
• @MissMulan That only applies if you are connecting nonexistent ideal voltage sources of non-equal voltage together with nonexistent ideal wires with no resistance. Jul 9, 2021 at 16:37
• This is fine so long as the batteries are more-or-less 'balanced' (all new and from the same package ideally). If your device goes to consumers who can put in 'whatever they want' (i.e. a bunch of batteries from a kitchen drawer), you run a very high risk of one or more leaking. Jul 9, 2021 at 19:29

## 1 Answer

Your calculations are correct.

The arrangement will work well provided the batteries are the same brand and model and are in the same state of charge. (i.e., Don't use three good batteries and one partially discharged.)

Due to the more gentle discharge current this 2P2S arrangement will give a higher output voltage and last longer than using 2S until discharged and then replacing with a second set.

Figure 1. AA cell terminal voltage and Ah rating at various discharge rates. Image source: Eneloop101.

Note on the graph that drawing 1 A from a single cell would result in a terminal voltage of about 1.25 V for most of the discharge cycle. Reducing the current to 0.5 A by paralleling two strings of cells would raise the output voltage by about 40 mV or so.