How do I wire my batteries in series?

Wiring batteries in series increases voltage while keeping amp-hours (Ah) the same. You do it by connecting positive to negative between batteries, then using the remaining open terminals as your main output.

Series wiring basics

• Voltage adds up (12V + 12V = 24V, 12V + 12V + 12V = 36V, etc.)

• Capacity (Ah) stays the same (two 12V 100Ah in series = 24V 100Ah)

How to wire it (step-by-step)

For two 12V batteries to make 24V:

1. Turn everything off and disconnect the charger and loads.

2. Connect Battery 1 positive (+) to your system’s main positive.

3. Connect Battery 1 negative (-) to Battery 2 positive (+) using a series jumper cable.

4. Connect Battery 2 negative (-) to your system’s main negative.

5. You now have 24V across the main positive and main negative.

For three 12V batteries to make 36V:

• Keep linking negative to positive from battery to battery in a chain, and use the first battery’s positive and the last battery’s negative as your main outputs.

Rules you need to follow

• Use matching batteries (same model, same capacity, same age). Don’t mix and match.

• Fully charge each battery before wiring so they start balanced.

• Use proper cable size for your current draw, especially on trolling motors and inverters. Undersized cables cause heat, voltage drop, and problems.

• Use a series-capable charger (example: for a 24V series bank, use a 24V lithium charger). Don’t charge a series bank with a 12V charger unless you charge each battery individually.

Quick check

After wiring, measure voltage across the main positive and main negative:

• ~25–28V for a charged 24V LiFePO4 setup

• ~38–42V for a charged 36V LiFePO4 setup

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