Sealed lead acid batteries have been the battery of choice for long string, high voltage battery systems for many years, although lithium batteries can be configured in series, it requires attention to the BMS or PCM. Connecting a battery in parallel is when you connect two or more batteries together to increase the amp-hour capacity.
There are three ways to connect your lead acid batteries—parallel, series, and a combination known as series/parallel. We cover each of these battery configurations in greater detail in our Battery Basics tutorial section of the site should you want to delve in a little deeper or reinforce what you already know.
Connecting batteries in series means to connect the positive terminal of the first battery to the negative terminal of the second battery and so on down the string. The interconnecting cables must have equal lengths and resistance to equalize of the load.
For example you can connect two 6Volt 10Ah batteries together in series but you cannot connect one 6V 10Ah battery with one 12V 20Ah battery. To connect a group of batteries in series you connect the negative terminal of one battery to the positive terminal of another and so on until all batteries are connected.
Connecting a battery in series is when you connect two or more batteries together to increase the battery systems overall voltage, connecting batteries in series does not increase the capacity only the voltage. For example if you connect four 12Volt 26Ah batteries you will have a battery voltage of 48Volts and battery capacity of 26Ah.
The same is done with positive terminals, i.e. the positive terminal of one battery to the positive terminal of the next. For example, let’s say you needed a 12V 300Ah battery system. You will need to connect three 12V 100Ah batteries together in parallel.