Deep Cycle Battery Charging 101

Deep cycle batteries are very different from starter batteries, which accounts for most automotive batteries. Understanding the difference between these two batteries and how deep cycle battery charging works will help you better choose a charger that meets your needs.

What is a Deep Cycle Battery?

A deep cycle battery is a battery designed to be deeply discharged and use most of the battery’s capacity. Starter batteries, which is what most vehicles are outfitted with, deliver shorter, high-current bursts of power to crank the engine. Only a small part of the battery is discharged as a result.

That’s not to say that deep cycle batteries cannot be used as starting batteries – they can. However, an oversized battery would likely be required due to its low cranking current.

A typical deep cycle battery will discharge 45-75% of its capacity, although this figure can vary depending on the battery’s construction and the manufacturer. While it is possible to cycle the battery down to 20%, it is considered best practice to keep the average cycle at around 45% to maximize the lifespan of the battery.

A deep cycle battery charger is recommended to maintain this cycle. The best deep cycle battery charger will also help protect against overcharging, so you can leave the charger plugged in 24/7 without worry of damaging the battery.

Types of Deep Cycle Batteries and Their Structure

There are two main types of deep cycle batteries: FLA (flooded) and VRLA (valve-regulated lead-acid). These two main types can be further subdivided.

There are two types of FLA batteries: flat plated and Tubular-plated Opzs. The two types of VRLA batteries include gel and AGM (absorbed glass mat).

From a structural standpoint, the main difference between a deep cycle battery and a cranking battery is that deep cycle batteries have thicker active plates. They also have thicker separators and a higher-density active paste.

The alloys used to create the plates in deep cycle batteries may have more antimony than cranking batteries.

The benefit to having thicker plates is that they better resist corrosion caused by extensive charge and discharge cycles.

What Are Deep Cycle Batteries Used For?

  • Boats

  • Cathodic protection

  • Motorized wheelchairs

  • Recreational vehicles

  • Electric floor sweepers and forklifts

  • Golf carts

  • Certain audio equipment

  • Sump pumps

  • Traffic signals

  • Off-grid energy storage for wind and solar   

Tips for Charging a Deep Cycle Battery

The process for charging a deep cycle battery is quite different from a conventional battery. For one thing, you’ll need to water the battery. If you’re not sure how do to this, we highly recommend that you read the instructions that came with the battery (you should read them regardless).

Many experts recommend charging the battery slowly over a 10-20-hour period at 70F. This way, the acid has plenty of time to penetrate the plates. Far less stress will be put on the plates, too.

It’s important to remember that your battery will self-discharge naturally 1%-15% each month in storage. Lead sulfation starts to kick in after the battery’s charge falls below 80%. Many battery chargers (provided they have damage protections in place) can be left plugged in 24/7 to keep the battery adequately charged until you’re ready to use it again.

4 deep cycle battery chargers to buy

There are several deep cycle battery chargers that you should consider to buy.

Minn Kota MK 460 PC Precision review

This particular charger is also very popular amongst the customers. And it is popular because of its efficient service and attractive features. 

Battery Tender 022-0148-DL-WH  review

When you talk about best  deep cycle battery charger available in the market, you really have to consider this particular unit. The features and services offered by this particular brand make this charger quite popular amongst the customers. 

Clore Automotive PL2410 SOLAR Pro-Logix Review

One of the industry’s best chargers, even distressed batteries can be rejuvenated when using the SOLAR, which will save you money over the long-term. With a weight of just 4.2 pounds, this is a small charger with a lot power.

NOCO Genius GENM3 Deep Cycle Battery Charger

The GENM3 is a three-bank, 12-amp charger (four amps per bank) designed for use with 12V lead-acid batteries, including MF, wet, AGM and gel. The great thing about this charger is that anyone can use it safely because it does not generate sparks.

It’s also compact, lightweight and waterproof, making it ideal for use with boat batteries.

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