How to Run Dual Batteries

Co-authored by wikiHow Staff

Last Updated: October 20, 2021 References

It makes sense if you think about it: more batteries means more power! Running dual batteries can give you more capacity or more volts, depending on how you hook it up. Fortunately, it’s actually really simple to connect 2 batteries together. You just need to do it correctly and safely. To make it easier, we’ve answered some of the most common questions that people have about what it takes to run dual batteries.

Question 1

Question 1 of 5:
Can I run 2 batteries in my car?

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Yes, you can wire them for 12 or 24 volts. Most cars use a 12-volt system and you can give your electrical system a boost by running 2 batteries at once. You’ll have literally twice the battery capacity if you wire them for 12 volts or twice the output if you wire them for 24 volts.^{[1]
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Question 2

Question 2 of 5:
How do you hook up dual batteries?

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You can hook them together in parallel for more capacity. Use a battery cable to connect the negative of one battery to the negative of the other battery. Then, use another cable to connect the 2 positives together. This will double your total battery capacity without increasing your amps or volts.^{[2]
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You can also hook them up together in series for 24 volts. To connect 2 batteries in a series, connect the 2 negatives of each battery to the positive of the other batteries with a battery cable. This will double your volts from 12 to 24.^{[3]
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Question 3

Question 3 of 5:
Can you run two batteries one alternator?

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Yes, as long as the batteries match. Your alternator actually recharges your batteries while your engine is running. If you have 2 batteries connected, and they’re the exact same type, then your alternator will charge both of them.^{[4]
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Question 4

Question 4 of 5:
What is a dual battery isolator?

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It keeps your batteries from draining each other. A dual battery isolator is a device that you can use to connect 2 batteries together without causing 1 battery to drain the power of the other battery. It essentially keeps the batteries isolated from each other.^{[5]
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Research source} To install one, connect the positive terminals of each battery to the isolator and connect a ground wire to a safe grounding location such as the frame of the car.^{[6]
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Question 5

Question 5 of 5:
Is a dual battery system worth it?

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Yes, if you need more power, it’s totally worth it. If you have a bunch of extra devices hooked up to your vehicle, such as lights and a sound system, they’re likely a major drain on your battery. By having 2 batteries hooked up to your vehicle, you have double the capacity to handle all of your devices.^{[7]
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