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14 things you need to know for Deep Cycle Battery

Table of Contents

What is a deep cycle battery?

A Deep Cycle battery is a battery designed to be regularly deeply discharged using most of its capacity. In contrast to car batteries which only provide short bursts of energy, deep cycle batteries are designed to provide sustained period over a longer period of time. The mainstream battery types in solar battery backup systems include Flooded Lead Acid (FLA) batteries, Gel Cell batteries, Absorbed Glass Mat (AGM) batteries and lithium batteries. Depending on the voltage, deep cycle batteries are divided into 12v battery, 24v battery, and 48v battery. The most common deep cycle RV battery, boat battery, and marine deep cycle battery are 12V, and the deep cycle golf cart batteries are normally 24V or 48V.

How to Read Deep Cycle Battery SPECS

A deep cycle battery is rated by the number of complete cycles that it will provide, as well as the depth of discharge that is allowable, and the amount of amperage that it will produce steadily. For instance, a deep cycle battery listing will tell you that it produces 75 Amp-Hours for a period of 20 hours, and is rated for 1000 full cycles at 80% depth of discharge. These numbers tell you how long the battery will last, how far you should be discharging the battery, how long you can expect to go before you need a battery replacement, and what kind of power you can expect in the meantime. With an ignition lead acid battery, the rating that matters most is the cold cranking amps (CCA), which only tells you how much power the battery can produce in a single burst at 32 degrees.

How to charge a deep cycle battery?

Sunlight, temperature, and battery type will influence specific charging times. To get a general idea, you’ll need to calculate amps delivered from your solar panels (total wattage/voltage of your battery). Then you’ll divide the amp hours of your solar battery by amps delivered. For example, if your marine battery system is set up by a 100ah 12v deep cycle battery with three 100 watt solar panels, your system would deliver 25 amps. By dividing 100Ah by 25 amps, you’ll learn it will take four hours for a 300 watt solar panel system to charge a 12v 100ah battery.

How long does it take to charge a 12v 100ah battery?

Sunlight, temperature, and battery type will influence specific charging times. To get a general idea, you’ll need to calculate amps delivered from your solar panels (total wattage/voltage of your battery). Then you’ll divide the amp hours of your solar battery by amps delivered. For example, if you have a 100ah 12v battery with three 100 watt solar panels, your system would deliver 25 amps. By dividing 100Ah by 25 amps, you’ll learn it will take four hours for a 300 watt solar panel system to charge a 12v 100ah battery.

How long do deep cycle batteries last?

The lifespan of a deep cycle battery varies by battery types. Normally, AGM batteries lasts about 4-7 years; Gel batteries lasts about 2-5 years; Flooded Lead Acid batteries lasts 4-8 years, and a high quality Lithium battery can last more than 10 years. The lifespan of a deep cycle battery also effected by battery cycles, maintenance, and the environment in which the battery is kept. For example, a Lead-acid battery’s cycle life can range from 500 to 1200, and a lithium battery can range from 2000 to more than 5000. Besides, a battery kept in a hot environment will experience a shorter lifespan than that in a cooler environment. Thus, for example, the same kind of lithium batteries, but when used as marine batteries and boat batteries, or work for an RV system, the actual service life may be somewhat different depending on the daily usage scenario.

Can I wire different battery types and sizes together?

We recommend wiring batteries of the same type and amp hour rating in your solar installation, i.e. if you go with absorbed glass mat batteries, all the batteries in your solar battery bank should be AGM batteries. This will limit any efficiency loss due to having different batteries.

How to tell if a deep cycle battery is bad?

The symptoms of a bad deep cycle battery show when the battery fails to maintain a charge, or shows sluggish performance, or has shorter run times. Or you can tell your battery is bad by finding things like a damaged terminal, bulge or bump in the case, crack or rupture of the plastic, excessive leaking, or discoloration. Terminals that are broken or loose might can cause a short circuit. When a battery short circuits, all the power is unloaded instantly, generating a lot of heat and can potentially cause the battery to explode. Also, cracks, splits, and holes may not cause a battery to stop working, but the battery should be labeled unsafe for safety reasons. If a physical check reveals nothing, try measuring the battery voltage. Make sure it is fully charged before carrying out a voltage check on it, and give it to rest for 3-5 hours. You can use a multimeter to measure your batter’s electrical value. As a well-functioning 12V deep cycle battery is fully charged, its voltage should range from 12.7V to 13.2V. If the voltage reading shows 0, it indicates a short circuit and a dead battery. If the voltage is below 10.5 volts, your battery has to be replaced. If the test reads 12.4 volts or less, but your charger indicates a fully charged battery, it means the 12 volt deep cycle battery is sulfated and will require replacement.

What are deep cycle batteries used for?

Brava provides high quality deep cycle batteries for solar systems, the BRAVA battery can be a great option for your RV, marine, and any solar panel system, perfectly meeting the power need of various scenarios. Add the stable, long-lasting, and compact deep cycle lithium RV batteries to your camper, keep your adventure empowered, and stay comfortable and safe on your journey. Upgrading your boat to the reliable BRAVA deep cycle boat batteries,the AGM, GEL, or Lithium deep cycle marine battery will allow you to enjoy more energy than a traditional flowing liquid battery. Enjoy more fun of being on the water, no need to worry about your deep cycle marine batteries running low after a long day of use. BRAVA also provides the 24v battery and 48v deep cycle battery. Use the 48 volt golf cart batteries to increase your cart’s range, top speed, and acceleration, while saving space and weight.

deep cycle battery for Golf Cart
deep cycle battery for Golf Cart

Types of Batteries (SLA, VRLA, AGM)

Batteries are divided in two ways, by application (what they are used for) and construction (how they are built). The major applications are automotive, marine, and deep-cycle. Deep-cycle includes solar electric (PV), backup power, traction, and RV and boat “house” batteries. The major construction types are flooded (wet), gelled, and sealed AGM (Absorbed Glass Mat). AGM batteries are also sometimes called “starved electrolyte” or “dry”because the fiberglass mat is only 95% saturated with Sulfuric acid and there is no excess liquid.

Flooded may be standard, with removable caps, or the so-called “maintenance free” (that means they are designed to die one week after the warranty runs out). All AGM & gelled are sealed and are “valve regulated”, which means that a tiny valve keeps a slight positive pressure.  Nearly all sealed batteries are “valve regulated” (commonly referred to as “VRLA” – Valve Regulated Lead-Acid). Most valve regulated are under some pressure – 1 to 4 psi at sea level.

Lifespan of Battery (Stop-Start, AGM, GEL, Deep-Cycle)

The lifespan of a deep cycle battery will vary considerably with how it is used, how it is maintained and charged, temperature, and other factors. It can vary to extremes – we have seen L-16’s killed in less than a year by severe overcharging and water loss, and we have a large set of surplus telephone batteries that see only occasional (10-15 times per year) heavy service that was just replaced after 35+ years. We have seen gelled cells destroyed in one day when overcharged with a large automotive charger. We have seen golf cart batteries destroyed without ever being used in less than a year because they were left sitting in a hot garage or warehouse without being charged. Even the so-called “dry charged” (where you add acid when you need them) have a shelf life of 18 months at most. (They are not totally dry – they are actually filled with acid, the plates formed and charged, then the acid is dumped out).

These are some typical (minimum-maximum) expectations for batteries if used in deep cycle service. There are so many variables, such as depth of discharge, maintenance, temperature, how often and how deep cycled, etc. that it is almost impossible to give a fixed number.

  • Starting: 3-12 months
  • Marine: 1-6 years
  • Golf cart: 2-7 years
  • AGM deep cycle: 4-8 years
  • Gel deep cycle: 2-5 years
  • Deep cycle (L-16 type etc): 4-8 years
  • Rolls-Surrette premium deep cycle: 7-15 years
  • Industrial deep cycle: 10-20+ years.
  • Telephone (float): 2-20 years. These are usually special purpose “float service”, but often appear on the surplus market as “deep cycle”. They can vary considerably, depending on age, usage, care, and type.
  • NiFe (alkaline): 5-35 years
  • NiCad: 1-20 years
deep cycle battery inside
deep cycle battery inside

No-load typical voltages vs state of charge

(at 10.5 volts = fully discharged, and 77 degrees F). Voltages are for a 12 volt battery system. For 24 volt systems multiply by 2, for 48 volt system, multiply by 4. VPC is the volts per individual cell – if you measure more than a .2 volt difference between each cell, you need to equalize, or your batteries are going bad, or they may be sulfated. These voltages are for batteries that have been at rest for 3 hours or more. Batteries that are being charged will be higher – the voltages while under charge will not tell you anything, you have to let the battery sit for a while. For longest life, batteries should stay in the green zone. Occasional dips into the yellow are not harmful, but continual discharges to those levels will shorten battery life considerably. It is important to realize that voltage measurements are only approximate. The best determination is to measure the specific gravity, but in many batteries this is difficult or impossible. Note the large voltage drop in the last 10%.

State of Charge 12 Volt battery Volts per Cell
100% 12.7 2.12
90% 12.5 2.08
80% 12.42 2.07
70% 12.32 2.05
60% 12.20 2.03
50% 12.06 2.01
40% 11.9 1.98
30% 11.75 1.96
20% 11.58 1.93
10% 11.31 1.89
0 10.5 1.75

What Are The Types of Deep Cycle Batteries?

The deep cycle function is applied to both lithium and lead acid battery technologies.
The lead acid battery can be divided into the flooded cell and the sealed lead acid battery. And the sealed lead acid category can be further split into AGM and gel cell batteries.
Each deep cycle battery type has its advantages and disadvantages, and you’ll have to decide what works best for you.

Let’s now look at these battery types separately:
1. Flooded Lead Acid
2. Absorbent Glass Mat (AGM)
3. Gel Cell
4. Lithium Ion

4Tips For Maintaining The Deep Cycle Battery

Here are a couple of pointers to keep your deep cycle battery in optimal condition:

  • Monitor charge levels: Start charging at 50% and don’t let the charge drop under 20%.
  • Charge even when not in use: This will help to prevent sulfation and maintain battery life. Trickle charge your flooded, gel, and AGM batteries if you’re not using them for a long time (lithium batteries don’t require this).
  • Rest the battery: Let the battery cool down after continuous use to avoid grid corrosion.
  • Clean battery extremities: Keep the battery terminal and covers free of dust and corrosion.

When to use a Deep Cycle Battery

Deep cycle batteries provide sustained energy, making them ideal for certain applications that require more than a quick start. Some of the most common uses for deep cycle batteries include:

  • Marine applications
  • Recreational vehicles
  • Materials handling, including forklifts
  • Golf carts
  • Off-grid renewable energy
6applications of deep cycle battery
6applications of deep cycle battery

For some applications, particularly marine uses, hybrid batteries are another solution. A hybrid marine battery can offer both a starter burst and sustained power for marine applications, but tends to have a shorter lifespan than a battery with a dedicated role.

Deep Cycle Battery vs. Lead-Acid Battery

Now that you know how these battery types work, it’s time to explore the benefits and shortcomings of each. Plus, we’ll dive into when to rely on deep cycle batteries versus when to install lead-acid batteries in your vehicles.

Use Cases

Because of their different designs, deep cycle and traditional lead-acid batteries work for vastly different scenarios.

  • Deep cycle batteries aren’t often found in everyday vehicles, like cars and trucks. Instead, they work to provide a steady supply of a lower amount of power compared to traditional batteries, making them ideal for recreational vehicles, boats, golf carts and electric vehicles, such as medical carts or electric bikes.
  • Traditional lead-acid batteries are probably familiar to most drivers, as these are common in many everyday vehicles, like cars, SUVs, trucks and other light-duty vehicles that need short bursts of power to start up the vehicle engine.

CCA vs. RC

When you’re looking into deep cycle batteries and traditional lead-acid batteries, you’ll come across the terms cold cranking amps (CCA) and reserve capacity (RC).

  • CCA indicates the number of amps a battery produces in 30 seconds at 0°C (32°F) while maintaining a minimum of 7.2 voltage.
  • RC is the number of minutes a battery can produce 25 amps with a minimum of 10.5 voltage.

A lead-acid battery will provide about two times more CCA compared to a deep cycle battery, while a deep cycle battery provides two or three times as much RC as a traditional lead-acid battery.

Pros of Deep Cycle Batteries

Deep cycle batteries have several benefits, depending on the situation. Many of their benefits, like sustained energy and long cycle lifespan, make them ideal for recreational vehicle use.

  • Cycles. Deep cycle batteries last for about 2,000 cycles, with each cycle representing a full discharge and recharge, while traditional lead-acid batteries last about 200 cycles and aren’t designed for deep discharging.
  • RC. A deep cycle battery has a much higher RC compared to regular batteries and provides more sustained energy.
  • Size. Deep cycle batteries are smaller and lighter in weight than regular batteries, which is why they work so well in recreational vehicles.

Cons of Deep Cycle Batteries

Not every vehicle will benefit from a deep cycle battery, as they do have some drawbacks that won’t allow them to work in every setting.

  • CCA. Deep cycle batteries provide half to three-quarters less CCA than a traditional lead-acid battery.
  • Power. With the lower CCA, deep cycle batteries do not provide the large bursts of power that a traditional lead-acid battery can provide to a vehicle.
  • Recharging. Users will need to manually recharge deep cycle batteries.

Pros of Lead-Acid Batteries

Lead-acid batteries are ubiquitous in many of the vehicles we come across every day because they have many benefits for modern cars and trucks.

  • Power. Lead-acid batteries provide large bursts of power to start a vehicle engine, and they rarely reach more than 20% DoD.
  • Recharging. The vehicle alternator helps recharge the battery, so users do not need to manually recharge traditional lead-acid batteries.
  • Cost. Lead-acid batteries are everywhere, and as the most common vehicle battery, they are easy to find and affordable.

Cons of Lead-Acid Batteries

Lead-acid batteries have some drawbacks that make them less suitable for certain applications, and unlike maintenance-free deep cycle battery varieties, they do require regular inspections and maintenance.

  • Limited capacity. Lead-acid batteries aren’t designed to reach a deep state of discharge the way that deep cycle batteries can and have a much lower RC compared to deep cycle batteries.
  • Maintenance. Lead-acid batteries need regular inspections and must be refilled to prevent battery damage.
  • Temperature resistance. Lead-acid batteries don’t hold up well to extreme temperatures, either hot or cold. The lifespan of lead-acid batteries can be cut short when used frequently in high heat or freezing temperatures.

Deep Cycle Battery FAQs

1. What Are Some Deep Cycle Battery Features To Consider?

Apart from Amp Hour, discharge cycle life, and depth of discharge, here are some other features you may want to consider in a deep cycle battery.

  • Size and weight: Smaller batteries are easier to carry and reduce overall vehicle weight.
  • Voltage rating: Higher voltage batteries should be used for larger loads.
  • Charging time: The smaller the number, the faster the battery charges.
  • Durability: Batteries can be susceptible to extreme temperatures, vibrations, shocks. Pick one suited to your usage.
  • Shelf life: The ideal shelf life for a deep cycle battery is 10 years before it loses maximum capacity.
  • Charging method: Note how the battery is charged. You can often use a smart charger to help adjust voltage and current.
  • Temperature tolerance: Check its ability to deliver power at different temperatures, especially if you live in very hot or extremely cold climates.

2. Where Are Deep Cycle Batteries Used?

Deep cycle batteries are used for anything that requires continuous power for an extended period.

These include:

  • RVs, golf carts, wheelchairs, scooters
  • Marine trolling motor, navigational devices
  • UPS backup technology, emergency lighting
  • Solar battery for off-grid energy storage systems

3. Can I Connect Different Deep Cycle Batteries?


Only connect batteries of the same type, model, capacity, and age.

For example, if you want to connect your deep cycle RV battery with another one to increase output, make sure the second battery meets the mentioned criteria.


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