Parallel batteries are batteries that have been installed side by side. In this type of
installation, positive terminals are connected to positive terminals and negative terminals are connected to negative terminals.
When batteries are connected in parallel, the capacity in terms of amp hours and kilowatt hours doubles. Voltage however remains the same.
More Than Double the Useable Energy Capacity?
When the rate of discharge increases in a lead acid battery increases, the useable capacity decreases. Conversely, when the rate of discharge increases the useable capacity increases. This is explained by Peukert’s law.
When we add a second battery in parallel to another, the average rate of discharge through each is split between the two. Each battery is therefore discharging at a slower rate. Each battery therefore has more useable energy capacity. Thus the rate has more than doubled.