Most off-grid power systems utilise deep cycle batteries to store energy. They can endure repeated discharging and recharging cycles without damage to their cells.
Deep cycle batteries vary in chemistry, architecture, and maintenance. They also cost significantly more than ordinary car batteries. You must, therefore, look after them properly and regularly to enhance their longevity.
Most battery systems today exploit automated management controls that check keep voltage and charge regulation. However, some tasks, like water top-up in flooded batteries, require on-site presence. Some varieties like the lithium-ion batteries require little human intervention.
Regardless of the type of your deep cycle batteries, this guide will help keep your setup running at optimum. Read on to discover how to avoid most of the problems related to battery banks.
Size Your Battery Banks
Battery bank sizing is paramount when determining the specifics of an off-grid energy system. It involves selecting a battery that can handle the load coming from the power source and supply enough power to all appliances. It should do this consistently without discharging to unhealthy levels.
When sizing, consider a load larger than your current energy requirements. The reason is that your needs will increase over time, and it's not advisable to add new batteries to a system of old ones. Battery voltage response varies with age, and stray currents will cause losses and inability to equalise.
Program the Battery Charger
Initial programming of chargers is essential to ensure that your battery bank charges at the recommended voltage and current. You should preset the voltage applied to the battery during the bulk, absorb, and float phases of charging.
The bulk phase supplies high current to refill charge and raise voltage rapidly. The charging rate slows down during the absorb cycle, which runs when the battery is 80 to 100 per cent full.
During the float phase, a little trickle charge keeps the battery bank at full state of charge (SOC). Setting the correct parameters allows the batteries to charge optimally, thereby maintaining their health.
Charge the Batteries Fully Periodically
To prevent cell degradation, consider bringing your batteries to a full state of charge, say after every three weeks. The system may achieve this automatically, but you want to be sure it happens. Full-charge averts internal corrosion and enhances cell equalization, boosting the health of the batteries.
Avoid Parallel Battery Strings
The best battery bank configuration consists of a single series of batteries. Never should you install more than three battery strings in parallel. With such a setup, the bank loses equalisation and accelerates the deterioration of weak cells.
It's also hard to detect weak cells because the surrounding ones compensate for them. In the long run, the entire system fails and costs you dearly to fix it.
Maintain Moderate Temperatures
Heat is a killer of virtually all types of batteries. They can lose about 25 per cent of their capacity when the temperature hits 30°F. The effect is more adverse at higher temperatures.
Therefore, it's advisable to keep your deep cycle batteries in a moderate temperature zone. Avoid sources of radiant heat, or install an earth-sheltered enclosure.
Temperature compensation is also vital due to the random heat variation. Hot conditions require a decrease in the charge voltage limit to avoid overcharging. When batteries get cold, you should raise the charge voltage limit for the bank to reach full charge.
Most power centres, charge controllers, and backup chargers come with the temperature compensation feature.
Corrosion of terminals and cables is a common nuisance in flooded battery installations. It causes electrical resistance and poses other hazards. Stopping it after it sets in can be challenging.
Fortunately, you can prevent it by applying a non-hardening sealant to the terminals before assembling your battery bank. Coat the wire lugs, nuts, and bolts entirely.
The sealant may not reach all the intended junctions if you apply it on an existing setup. Corrosion will begin as soon as acid or water comes into contact with uncovered metal parts.
You can purchase some compounds designed to protect battery terminals or household petroleum jelly. Apply a thin layer on the exposed parts with your fingers, and it won't hinder electrical contact.
Clean the Battery Top Occasionally
Acid spatters or dust accumulated on the surface of your deep cycle batteries makes the setup untidy. It also increases the chances of corrosion and the flow of stray currents which waste energy.
When properly sealed, you can rinse the battery top with a wet cloth twice a year. Beware of using too much water, lest you short circuit the battery. Wipe the surface dry soon after cleaning it.
Install Low-Voltage Disconnects
A total battery drain can cause a permanent loss in battery capacity and a reduction in its lifespan. The load circuits in your system should include the low voltage disconnect (LVD) feature.
Many charge controllers and inverters on the market have the component built-in. If not included in your gadgets, be sure to purchase one. It can save your deep cycle batteries in the case of accidental severe discharging.
Add Water to Flooded Batteries
For wet-cell or flooded batteries, the plates must stay submerged in the electrolyte. Inspect the acid level and add distilled or deionised water if it falls below the recommended amount.
However, don't top-up discharged batteries since they absorb the electrolyte when draining charge. If you do it, the liquid might become excessive once you recharge the battery.
A battery in charging mode produces hydrogen, so you shouldn’t tamper with cables. Sparks can trigger an explosion and ignite a fire.
Deep Cycle Batteries - Final Thoughts
Deep cycle batteries are indispensable when developing an off-grid power system. They are useful in many areas of application, including powering homes, recreational vehicles, and marine vessels.
They require attention for smooth operation, but their maintenance doesn't have to be stressful. With correct installation and the knowledge of the necessary upkeep procedures, they can serve you smoothly for years.
The batteries come in various versions, such as flooded, absorbed glass mat (AGM), and gel batteries. We have provided several maintenance tips applicable in most deep cycle batteries.
If you are looking to install a battery bank, we are here to help. Contact us for supplies and expert advice on everything to do with deep cycle batteries.