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How Much Power does a Deep Cycle Battery Hold?

How Much Power does a Deep Cycle Battery Hold?

Have you ever wondered just how much power is sitting inside a fully charged deep cycle battery?

Maybe you’re wondering if it’s powerful enough to run all of your boat’s electronics, a TV, or even an electric scooter. Or maybe you’re just curious about how to determine the battery’s energy density.

Either way, keep reading!

In this article, we’ll answer all of your questions related to deep cycle battery power and how to determine just how powerful your battery is.

Ready to dive in?

How Much Power Does a Deep Cycle Battery Hold?

Renogy Deep Cycle AGM Battery 12 Volt 100Ah for RV, Solar Marine and Off-grid Applications

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Deep cycle batteries are known for being pretty powerful, but just how much power can they hold?

The answer, of course, depends on each individual battery.

Not all deep cycle batteries are created equally. They come in many different sizes, strengths, and qualities, and even those that look similar may be made with different power capacities for different needs.

Generally, larger batteries for larger boats have more power than small batteries. Batteries are divided into groups based on their size, and as we’ll see below, larger group sizes usually (though not always) mean more power.

How much power a battery holds may also depend on its age, how it has been used and cared for, and even the quality of materials used to make it.

So, how do you determine how powerful a specific battery is?

According to this helpful article from Omni Calculator, there are two numbers that determine a battery’s capacity to hold power:

  • Voltage: Voltage describes the battery’s potential to produce an electric current. Most marine deep cycle batteries are 12V, though some larger batteries used for powering larger devices are 24V.
  • Amp hour rating: The amp hour rating (Ah) is the maximum number of amps a battery is able to produce in an hour. Amp hour ratings on deep cycle batteries can range from 20 Ah up to 125 Ah or more.

The energy density of the battery, or its power capacity, is calculated by multiplying voltage and amp hours. It is expressed using watt-hours.

Power By Battery Group Size

Batteries part 5 (BCI group sizes explained)

Group size refers to the basic dimensions of batteries in a specific class. The power capacity of each battery within a group size will vary, but in most cases, the batteries with larger group size numbers will be more powerful.

Let’s take a look at some common marine battery group sizes and their typical power capacities:

24M
  • Voltage: 12V
  • Amp hours: 70 to 85
  • Energy density: 840 to 1,020 Wh
25
  • Voltage: 12V
  • Amp hours: 40 to 55
  • Energy density: 480 to 660 Wh
27M
  • Voltage: 12V
  • Amp hours: 85 to 100
  • Energy density: 1,020 to 1,200 Wh
31M
  • Voltage: 12V
  • Amp hours: 100 to 125
  • Energy density: 1,200 to 1,500 Wh
34M
  • Voltage: 12V
  • Amp hours: 50 to 70
  • Energy density: 600 to 840 Wh
35
  • Voltage: 12V
  • Amp hours: 44 to 60
  • Energy density: 528 to 720

Deep Cycle Battery Vs. Car Battery: Which One Holds More Power?

Comparing marine deep cycle batteries to car batteries is like comparing apples to oranges. They are two different types of batteries made for very different uses, so there is not much reason to compare them against each other.

Car batteries and deep cycle batteries may have similar voltage and amp hour ratings, but they cannot be used interchangeably.

Deep cycle batteries, particularly those made for marine use, are thicker and tougher than car batteries, and they are made with sturdier lead plating so they can handle more vibrations--essentially, a deep cycle battery can take more abuse than a car battery.

VMAX857 AGM Battery 12 Volt 35AH Marine Deep Cycle HI Performance Battery ideal for boats

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Additionally, car batteries are starting batteries--they are only meant to supply a short burst of power to start the engine. Once the engine is running, its alternator continually recharges the battery. The battery itself is not intended to be discharged below 80 to 85 percent.

Interstate Batteries Automotive Battery 12V 63Ah (MTZ-34) Automobile Battery for Cars

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Deep cycle batteries are meant to power boat electronics for a longer period of time. They are not connected to the engine so they cannot be recharged by the alternator. They are frequently discharged down to 50 percent or even lower.

So again, which one holds more power will depend on group size, voltage, and amperage, but they are not for the same uses and so it is pointless to compare them against each other.

FAQ

Can a Marine Battery Power a TV?

Most marine batteries have more than just boating related uses. It may be possible to use a marine battery to power a TV, but how long it will supply this power depends on the size of the battery and the TV.

For example, a 100Ah battery will supply 35 watts of power to a 32-inch TV for about 34 hours. A smaller TV, drawing about 20 watts of power, will receive 60 hours of power from the same battery.

If you want to use a marine battery for your TV, this battery below is a good choice.

JITA 12V 100Ah LiFePO4 Lithium Battery RV Deep Cycle Battery, Built-in 100A BMS, 10 Year Life, 1280W...
  • [Lithium Iron Phosphate Battery]: JITA LiFePO4 Deep Cycle Battery provides 2000~5000 cycles, which is more than 10 times to Lead Acid Battery with 300~500 cycles. 10 Years Lifetime. 100Ah lithium...
  • [Built-In BMS Protection]: JITA 12V Lithium Battery has Built-In BMS (Battery Management System) to maintain the voltage of every cell and protect it from overcharge, over-discharge, overload,...

Can Marine Battery Power a Scooter?

Yes, many marine batteries can be used for scooters and electric wheelchairs. If you’re buying a marine battery for this specific purpose, it’s best to find one that specifically states it can be used for a scooter.

Also, you’ll want to make sure it has the proper voltage and amperage for your specific scooter. This battery below is a good place to begin your search.

Sale
WEIZE 12V 75AH Deep Cycle Battery for Wayne ESP25 WSS30V Backup Sump Pump, Trolling Motor, Solar...
  • TL1275/FP12750 Battery 12V 75AH Sealed Lead Acid Rechargeable Maintenance Free AGM Deep Cycle; Parcel: 1 x Battery (screws included, but no wire harness or mounting). TL1275 or FP12750 You Will...
  • Dimensions: 10.02 x 6.65 x 8.94 inches. High Performance, Long Service Life and Deep Discharge Recover.

Can a Marine Battery Power a Golf Cart?

Yes, some marine batteries can also be used in golf carts. Again, though, make sure it has the proper voltage and amperage. Double-check before buying any battery to find out if it will work for your specific need.

This battery below works well for golf carts.

WEIZE 12V 100Ah Deep Cycle SLA Battery, Rechargeable for Solar Wind RV Marine Camping UPS Wheelchair...
  • Dimensions: 12.99x 6.73x 8.43 inches (Replace UB121000, Renogy 100 AMP Hour). This sealed lead acid battery has a maintenance-free and spill proof design.
  • Deep Cycle Battery 12V 100 Amp Hour Sealed Lead Acid Rechargeable ; Parcel: 1 x Battery (screws included, but no wire harness or mounting).

Conclusion

Some deep cycle batteries are larger and more powerful than others. They come in different sizes and are made for different uses. You can determine how much power a specific deep cycle battery holds by multiplying its voltage and amp hour rating.

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