Wiring batteries in series or parallel
Pick your batteries and your system voltage: we tell you how to wire them, what you get in total, and we draw the diagram.
Voltage of each battery
Ah
How many batteries?
Voltage you want for the system
2 strings in parallel, of 2 batteries in series each.
24 V
voltage
200 Ah
capacity
4.8 kWh
total energy
- • Take the + at one end of a string and the − at the other end (diagonally): all the batteries work equally.
In series: volts add up
One battery's + to the next one's −. Two 12 V 100 Ah batteries in series: 24 V 100 Ah.
In parallel: amp-hours add up
All + together, all − together. Two 12 V 100 Ah batteries in parallel: 12 V 200 Ah.
Rules to follow
- Matching batteries: same type, same capacity, same age. An old battery in a new bank drags the others down.
- As few strings in parallel as possible: three or four at most. Beyond that, raise the system voltage or use bigger batteries.
- Cables of the same length and size for each string, or one string works harder than the other.
- Lithium: check that the manufacturer allows series wiring, and how many batteries at most. Each battery's BMS has its limits.
- Fully charge each battery before wiring them together, so they start at the same level.