If you have ever used recreational vehicles, boats, or extensive power systems, you must be conversant with deep cycle batteries. These are batteries that are designed to discharge using most of its capacity deeply. A deep cycle battery delivers a steady amount of current over a long period.
There exist two types of deep cycle batteries: Flooded battery and Valve-Regulated lead-acid battery (VRLA). The valve regulated battery is further subdivided into Absorbed Glass Mat (AGM) and Gel.
A deep cycle battery has some merits:
- No hydrogen emission, and this minimizes the need for ventilation.
- It has a slow self-discharge rate; thus, it can be stored for a long term.
- It can withstand intense discharges periodically without being damaged.
- It is more resistant to shock, temperature variation, and vibrations.
- It doesn't need regular maintenance. It is usually termed as a free maintenance battery.
- The sealed case allows the deep cycle battery to be transported or stored at different orientations.
- It is designed to have low internal resistance; thus, it charges fast.
- With proper maintenance, a deep cycle battery is durable.
Charging of a deep cycle battery is a critical practice that you should understand very well. Using a specified battery charger of the correct rating is essential. Incorrect charging practices periodically may damage the battery explosion, battery leak, or battery explosion.
It is recommended you use a float charger with a battery charger amp meter. This will enable you to monitor the electric current being delivered to the battery by the charger. Most importantly, a deep cycle battery can be deeply discharged and recharged many times.
What amps should you charge your deep cycle battery?
It is vital to ensure you use the correct charging rate for your deep cycle battery. The batteries are designed for particular applications and thus come in different sizes and capacities. Others have a higher amp-hour rating than others.
Charging a small deep cycle battery with a high charge rate, say 15amp, will either overcharge it or damage it. Likewise, charging a large deep cycle battery with a low charging rate will damage the battery and take too long to charge fully.
Therefore, your charger's amp rating's choice depends on the amp-hour rating of the deep cycle battery. For example, a small 12-volt deep cycle battery can be charged with a 2 amp rated charger. A 100 amp-hour deep cycle battery should be charged with a higher amp rating of 10 amp and above.
Besides, there are industry standards for deep cycle batteries. Since they come in different sizes, there exist group sizes following their physical size and terminal placement. BCI codes include U1, 24, 27and 31.
Below are approximate ratings for different group sizes:
- U1- 34 to 40 amp-hours.
- Group 24- 70 to 85 amp-hours.
- Group 27 – 85 to 105 amp-hours.
- Group 31 – 95 to 105 amp-hours.
Furthermore, these ratings are found on the back of your deep cycle battery. Charging rates will differ according to the type of deep cycle battery. For instance, Gel batteries require slow charging rates, preferably two amps. They cannot be fast-charged using an automotive charger as they are damaged.
Likewise, Absorbed Glass Mat (AGM) can be charged at high charging rates. This is because AGM batteries are designed with low internal resistance, thus no heating of the battery under heavy charge currents.
How long does it take to charge a deep cycle battery at 2 amp or 10 amp?
Charging time is of great concern to customers. Short charging time for a deep cycle battery is desired. However, fast charging a deep cycle battery can lead to other problems depending on the battery's size. The major problem of fast charging is that the plates inside the deep cycle battery start buckling. This reduces the performance characteristics of the battery.
Charging depends on the number of amp-hours the deep cycle battery stores. To get the approximate time taken, divide the amp hour rating of the deep cycle battery by the charger's amp-hour.
At 2 amp, it will take 24 hours for a fully discharges deep cycle battery to receive 48 amps of charge. At 10 amp, it will take approximately 4.8 hours to charge a 48 amp deep cycle battery fully.
Can you overcharge a deep cycle battery at 2 amp or 10 amp?
To be straightforward, this depends on the type of deep cycle battery used. Overcharging occurs when the battery charger continues to deliver current into the battery even after a full charge.
Using a 2 amp or 10 amp trickle charger to deliver current to a deep cycle battery will undoubtedly lead to overcharging. A trickle charger will continuously charge even after a full charge causing overcharging.
On the other hand, using a 2 amp float charger will take the battery to its optimum charge, and the battery charger will stop charging once fully charged. This type of charger falls under automatic chargers.
An automatic charger is designed to have an automatic setting that determines how much charge your battery needs. The inbuilt technology switches from 10 amp fast charging to 2 amp slow charging. Once the deep cycle battery fully charges, the battery charger automatically stops further charging.
As earlier mentioned, overcharging reduces the deep cycle battery’s life expectancy. The plates buckle due to excess heating. Apart from the current being delivered to the battery, the voltage setting is also essential. A battery charger will determine voltage requirements automatically, and so any adjustments are needed.
As we have seen, deep cycle batteries deeply discharge to about 80% of its capacity and recharged many times. Most people have opted to purchase these batteries due to their explicit performance.
However, for you to continue using your deep cycle battery for whatever application, you must maintain and service it regularly as per the manufacturer’s guide.
Ensure you have acceptable charging practices. You should know your deep cycle battery's features very well, including capacity and current rating. The type of charger you use will have an impact on the performance of your battery. It is advisable to use automatic chargers as they guarantee an extended lifespan.
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