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What is the Difference Between a Deep Cycle and an SLI Battery?

Power - by Bryan Veldboom - updated on 9/14/2023

SLI and deep cycle Duracell Ultra batteries sitting on a counter

Looking for a new car battery, golf cart battery or trolling motor battery? Before you go shopping, be sure that you understand the differences between deep cycle and SLI batteries. Deep cycle batteries are designed to work very differently from SLI batteries and the two should never be used interchangeably. Confused? Don't worry, this article will help break down how deep cycle and SLI batteries work, what applications they're used for and how they should be maintained.

What is the Difference Between SLI and Deep Cycle Batteries?

SLI Batteries (short for Starting, Lighting, Ignition) - SLI batteries are designed to provide a large dose of power for a very short period of time, typically less than a minute or two.

Deep Cycle Batteries - Deep cycle batteries have thicker lead plates inside them than SLI batteries, which allows them to provide a constant flow of power for a much longer period of time, typically several hours.

What are SLI and Deep Cycle Batteries Used for?

SLI Batteries - SLI batteries are used exclusively as starting batteries. They deliver the power needed to start the engine in a variety of vehicles, including cars, trucks, RVs, boats, motorcycles, ATVs and other powersport applications.

Deep Cycle Batteries - Because of their long-term power capabilities, deep cycle batteries are used to power vehicles that do not have a traditional engine, such as electric golf carts, wheelchairs and mobility scooters. They are also used as the "house" battery on RVs and boats, and as a source of backup power for UPS units, sump pumps, telecom applications and emergency medical equipment.

What is the Acceptable Depth of Discharge for SLI and Deep Cycle Batteries?

Rechargeable batteries should only be discharged to a particular percentage of their overall capacity. As you can see below, SLI and deep cycle batteries feature a very different ideal depth of discharge.

SLI Batteries - Should not be discharged below 50% of their total capacity.

Deep Cycle Batteries - Can withstand discharges of 50-80% of their total capacity.

What is the Difference Between SLI and Deep Cycle Charging?

Since SLI batteries are used as starting batteries, they are recharged by the vehicle's alternator. Sometimes an external SLI battery charger is used to maintain the battery when the vehicle is in storage or when it hasn't been driven for long periods of time.

Deep cycle batteries always require an external battery charger. A deep cycle battery should be fully charged every day that it's used, even if it's only discharged by 25% of its overall capacity. Always be sure to charge a deep cycle battery to 100% capacity.

Batteries Plus is Your SLI and Deep Cycle Battery Headquarters

No matter what the application, you're sure to find a solution at Batteries Plus. Shop our selection of battery solutions online, or find what you need at your nearest Batteries Plus location. Want to learn more about this topic? Our blog is full of useful articles, including "How to Troubleshoot Your Deep Cycle Battery."

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