NOCO - Series And Parallel Charging - Support

Series And Parallel Charging

Often times, a situation arises where a system (“system” can pertain to a car, boat, truck, tractor, home, etc.) is in need of a battery set-up that may not be readily available for purchase. To solve these power issues, batteries are often linked together to meet the requirements of a specific application. This article was made to assist you in understanding the difference between batteries wired together in Series versus batteries wired in Parallel, and how to select the right charger for each circumstance. 

Connecting in series stacks up the voltage of each battery, allowing for a higher electrical force. This type of set-up is necessary to start vehicles that require a large amount of voltage. Wiring in series does not affect the amp hours (overall capacity) of a system of batteries, just how must power it can output at once. In order to connect in a series, the negative terminal of one battery connects to the positive terminal of the next battery (and so on in this pattern) until it feeds back into the system (i.e. the boat's electronics), while the positive terminal is attached directly to the boat's engine and the first battery in the series.

Connecting in parallel stacks up the amp hours of each battery, allowing for a longer use. This type of set-up is for systems that use a lower voltage, but are used for longer periods of time. Wiring in parallel does not affect the voltage (power delivered) of a system of batteries, just how long the batteries can be used until they die. Connecting in parallel requires you to connect the negative terminal of one battery to the negative terminal of the next, as well as connecting the positives to the positives. Using each battery terminal lead ensures that the voltage stays the same, but the overall capacity increases.

A system that contains two or more batteries being used for separate power applications is a mixed system. Mixed systems come in a wide variety, for a wide array of uses. Our products deal with applications that require the battery charger to output 12 volts (used in the examples below). These set-ups are particularly prevalent in boats, where one battery is a starter battery (instant power), and the remaining batteries are deep cycle (power over time) batteries. In this example, starter batteries power a boat's electronics, while the deep cycle battery system provides steady power to the trolling motor.

While selecting the correct charger to charge and maintain batteries which are wired in series using Genius or GEN Chargers, the battery system must equal out to 12V (unless using the 24V mode on our larger chargers, the batteries must equal 24V). In the examples below, two 6V batteries in series = 12V. This requires only one bank of a 12V charger to be attached to the positive terminal of the first battery, and the negative terminal of the second battery. In the second example, to charge a 24V system simply use each bank of the charger on each 12V battery terminal leads.

While selecting the correct charger to charge and maintain batteries which are wired in parallel using Genius or GEN Chargers, the important number to know is the overall amp hours of the system. When charging in parallel, you are not charging to the voltage of the system (unlike series, which only focuses on voltage) you are charging the amp hours, kind of like recharging your phone at the end of the day. In the examples used below the first system equals 200Ah, this would require a 12V battery charger that is rated for at least 200Ah. In the second example, the two batteries equal 400Ah. This would require a charger rated for 400Ah, and so on. The GEN2 charger, used in the graphics below, is rated up to 230 amp-hours per bank, meaning each bank can handle a separate 230 Ah battery. Click either of the images below to view the NOCO Gen series on-board chargers.

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