Glossary

Battery bank

Unit Ah

What is Battery bank?

Several interconnected batteries operated as one store — in parallel for more capacity, in series for a higher system voltage.

What matters about Battery bank in practice?

A battery bank should only combine batteries of the same type, the same capacity and, as far as possible, the same age. One weak battery drags the others down with it.

Symmetrical wiring is important: positive from one end, negative from the other, equal cable lengths to each battery. Otherwise one battery is loaded more heavily than the others and ages faster.

Connect in parallel or in series?

  • In parallel: the voltage stays the same and the capacity adds up. Two 12 V batteries with 100 Ah each give 12 V and 200 Ah.
  • In series: the voltage adds up and the capacity stays the same. Two 12 V batteries with 100 Ah each give 24 V and 100 Ah.

How is a battery bank wired correctly?

Take positive from the first and negative from the last battery so that all batteries are loaded equally. The interconnecting cables have the same length and cross-section. On the negative side a busbar helps to bring all cables together cleanly.

What applies to lithium batteries?

The manufacturer specifies how many batteries may be connected in parallel or in series and whether each battery needs its own fuse. Charge batteries of different age or state of charge fully one by one before connecting them, so that they start level.

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