Quick Answer
You can typically connect up to 4 batteries in series to a single PWM charge controller, and up to 2 batteries in parallel to a single charge controller. However, this depends on the charge controller's specifications, particularly its maximum current rating and the battery bank's total voltage.
Understanding PWM Charge Controllers
A PWM (Pulse Width Modulation) charge controller is designed to regulate the flow of energy from your solar panels to your battery bank. When it comes to connecting multiple batteries to a single PWM charge controller, there are two main configurations to consider: series and parallel.
Series Configuration
In a series configuration, batteries are connected one after the other, with the positive terminal of one battery connected to the negative terminal of the next. This increases the total voltage of the battery bank, but the total current remains the same. When connecting batteries in series, make sure the total voltage does not exceed the maximum voltage rating of the charge controller.
For example, if you have 12V batteries and want to connect 4 of them in series, you would connect the positive terminal of the first battery to the negative terminal of the second, and so on. The resulting battery bank would have a total voltage of 48V (4 x 12V).
Parallel Configuration
In a parallel configuration, multiple batteries are connected at the same voltage level, with the positive terminals connected together and the negative terminals connected together. This increases the total current capacity of the battery bank, but the total voltage remains the same. When connecting batteries in parallel, make sure the total current does not exceed the maximum current rating of the charge controller.
For example, if you have 2 x 12V batteries connected in parallel, the resulting battery bank would have a total voltage of 12V (same as the individual batteries) and a total current capacity of 2 x the current of a single battery.
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