Charging Deep Cycle Batteries and Charging AGM Batteries

Charging Deep Cycle Batteries and Charging AGM Batteries

Charging Deep Cycle Batteries and Charging AGM Batteries     

Incorrect charging is the main cause of damage to deep cycle batteries but can be easily avoided by following simple procedures and safety advice. Keeping your battery at the correct state of charge improves lifespan as well as reducing the risk of running out of power when away from home.

Charging is also an important consideration when storing your battery. Deep cycle batteries will self-discharge if left without a load over an extended period of time and storing in an uncharged state can cause sulfation and damage performance.

To help you get the most out of your 12 volt deep cycle battery and understand more about the charging process, we’ve put together a deep cycle battery charging guide. The Aussie Batteries & Solar experts are also available to answer your questions; just give us a call on 1800 853 315.

Bulk, Absorption and Float Charge

Battery charging occurs in three stages; bulk, absorption and float charge. Bulk charge refers to the first stage of the battery charging process, in which the rated maximum current is sent to the battery while maintaining a constant voltage. After this comes the absorption charge stage, which sees the voltage gradually lower as internal resistance increases. The final float charge stage occurs after the battery reaches its full charge and the charging voltage is reduced. This process is often referred to as a ‘maintenance’ or ‘trickle’ charge and is intended to keep an already charged battery from discharging.

Solar charge controllers are also able to perform this function by sensing voltage drops in the battery and sending short ‘pulses’ to prevent loss of charge. A ‘pulse’ is a very short charging cycle and may occur several hundred times per minute. Although AGM deep cycle batteries self-discharge at a lower rate than standard lead-acid batteries, they will still require this type of ongoing maintenance charge or at least monthly top-ups to avoid damage.

How does a battery charger work?

The deep cycle battery charger has three main jobs: getting charge into the battery, optimising the charging rate and stopping when the battery has reached full charge. Smart chargers work with most battery types and use the battery’s voltage to detect the type of battery and charge needed.

Look for a smart charger that also comes with reverse pulse technology as this can help reduce battery temperature when charging. If you are not using a smart charger to charge your 12V deep cycle batteries, the charging current should be at least 10% of the amp hour rating for a flooded lead acid battery or up to 30% for an AGM lead acid battery. Find out more about choosing a deep cycle battery charger.

Charging time

Charging time is the time it takes for the reconstitution of the battery’s active chemicals to be completed while the cell temperature is kept at a safe level. This process stops when the termination voltage has been reached in order to avoid overcharging.

The charging time for deep cycle batteries depends on the number of amp hours it stores. Divide the amp hour rating of your battery by the amp rating of the charger and you’ll have an estimate of the time needed to reach full charge. For example, a 100 amp hour battery at a 50% stage of charge (50 amp hours) would take approximately five hours to charge on a ten amp battery charger.

It’s important to avoid overcharging as this can cause grid corrosion and severely reduce battery life. The excessive heat this creates can also cause the plates within the cells to buckle and shed their active material. Using a smart charger can help avoid the problem of overcharging as it will automatically switch off when the correct level of charge has been detected.

Charging from Solar

Investing in solar panels will allow you to charge your deep cycle battery with free energy from the sun, even when away from mains power. After panels have been placed in the sun, they will need to be attached to a solar regulator, also known as a charge controller. 12 volt solar panels can produce fluctuating power that would damage a battery if left unregulated but the solar charge controller keeps this voltage at a safe level. Most solar regulators also have the technology to switch to float charge when the battery has reached full capacity; eliminating the problem of overcharging.

While charging from solar is dependent on the weather and can involve an initial setup cost, solar panels provide an inexhaustible and environmentally friendly energy source for your batteries.

Find out more about the Aussie Batteries & solar Range of 12 volt deep cycle batteries.

July 1, 2014 | By Nathan Gathercole| Comments
About Nathan

Nathan is the owner of Aussie Batteries & Solar, and has been immersed in the battery industry for many years. Growing up on the Sunshine Coast, he enjoyed taking full advantage of the spectacular outdoors on offer, and has turned this passion into a thriving business. As the saying goes, "Find a job you love and you will never have to work a day in your life".