The single most important factor to consider when purchasing a deep-cycle battery for a renewable energy application is cycle life, which is the number of discharge/charge cycles the battery can provide over its lifetime. Many find that deep-cycle batteries used in renewable energy (RE) applications never reach their expected cycle life, but they do not know why. The answer is simple - the occurrence of Partial State of Charge (PSOC) in which the batteries are often never fully recharged on a regular basis.
Operating at PSOC can quickly diminish the overall life of a battery, which results in frequent, costly battery replacements. Because deep-cycle batteries are critical components of any renewable energy, telecom or inverter backup system operating in off-grid or unstable grid locations, many battery manufacturers have focused on finding ways to combat the negative effects PSOC has on deep-cycle battery banks.
Consistent PSOC cycling is harmful to the battery and leads to significant reductions in cycle life. Addressing the issue of PSOC and its impact on battery performance and overall life has remained a challenge - until now. Advancements in carbon technology and its addition to lead acid batteries has shown to extend the life of deep-cycle batteries designed for RE, telecom and inverter backup applications.
Old Fort Village will be the Caribbean’s first totally self-sustained, green technology development featuring a battery bank of batteries with Smart Carbon.
A recent implementation of lead acid batteries featuring carbon additives is at Old Fort Village in St. Ann, Jamaica, an off-grid community of townhouses and apartment residences that rely completely on solar power featuring an energy storage solution using deep-cycle batteries with carbon technology. Once completed, Old Fort Village will be the Caribbean’s first totally self-sustained, green technology development featuring a battery bank of 144 Trojan IND-33 2V batteries with Smart Carbon. The Trojan Smart Carbon batteries will store energy captured by multiple photovoltaic arrays that are managed by a state of the art off-grid energy management system.
Old Fort Village required a solution that could take maximum advantage of the island’s peak sunshine, while at the same time save residents money on electricity -- a very expensive commodity in Jamaica. The entire compound’s electrical loads including lighting, televisions, appliances, air conditioning, as well as pool pump and heater will be powered by the solar electric system, while hot water will be provided by solar thermal water heaters.
Jamaica currently has the second highest electricity rate in the Caribbean and all the Americas at nearly 40 cents per kWh for a supply which is undependable with irregular fluctuations and power surges. The grid can even be non-existent for days or weeks during and after hurricanes and storms. The Old Fort Village renewable energy system is designed to be immune to these power supply problems, and provides tremendous cost savings to residents on electricity bills. Currently it is estimated that utilizing the grid is 72% more expensive than tapping into energy stored in battery banks as part of a solar system.
Deep-cycle flooded batteries are still the most widely used battery technology due to their widespread availability and more economical price point.
Deep-cycle flooded batteries featuring carbon additives provide reliable power for the types of PSOC applications inherent in locations such as the Old Fort Village complex. While most carbon additive research has focused on VRLA batteries for start-stop automotive applications, the addition of carbon to deep-cycle flooded batteries for stationary applications is increasing. Deep-cycle flooded batteries are still the most widely used battery technology due to their widespread availability and more economical price point, so the addition of carbon formulas to these types of batteries is sure to gain widespread adoption worldwide.
Smart Carbon helps enhance overall battery life in an application where the batteries are not fully recharged on a regular basis.
Extensive research has been done by engineering teams at some of the world's leading battery manufacturers to determine what types of carbon in what formulas can successfully address the effects of PSOC.
Trojan Battery’s Smart Carbon proprietary formula, which provides improved performance when deep-cycle flooded batteries consistently operate in PSOC.
Smart Carbon helps enhance overall battery life in an application where the batteries are not fully recharged on a regular basis, and is currently featured in Trojan’s Industrial and Premium flooded product lines.
Be sure to also read information from leading industry research organizations on the use of carbon additives in deep-cycle batteries: Advanced Lead Acid Battery Consortium (ALABC) and Battery Council International (BCI). These market and technology research firms have conducted independent studies on the use of carbon in lead acid batteries, and have found that the use of carbon on a battery’s negative plates dramatically reduces sulfation at PSOC, which is the leading cause of shortened cycle life of lead acid batteries.
While PSOC cycling will continue to be an issue in renewable energy applications, there are now special carbon forumulas available from battery manufacturers to address the challenge of PSOC. Deep-cycle batteries offering carbon additives can provide higher conductivity, reduced sulfation and improved opportunity charging, as well as offer up to 15% improved battery cycle life in PSOC applications versus batteries that do not contain carbon additives.
Written by Dean Middleton, Senior Director of Global Sales for Trojan Battery Co., LLC