Energy Storage

Rechargeable batteries are usually used to store the energy generated from the renewable energies. However, cares must be taken in the selection of battery types which affect the performance and life of the system. Deep-cycle batteries should be used which can sustain a fair amount of overcharge and deeper discharge.

There are 2 main applications for the rechargeable batteries – Starter and Deep-Cycle:

Starter Batteries are meant to get combustion engines going. These lead acid batteries have many thin lead plates which allow them to discharge a lot of energy very quickly for a short amount of time. However, they do not tolerate being discharged deeply, as the thin lead plates needed for starter currents degrade quickly under deep discharging and re-charging cycles. Most starter batteries will only tolerate being completely discharged a few times before being irreversibly damaged.

Deep-Cycle batteries have thicker lead plates that make them tolerate deep discharges better. They cannot dispense charge as quickly as a starter battery but can also be used to start combustion engines. You would simply need a bigger deep-cycle battery than if you had used a dedicated starter type battery instead. The thicker the lead plates, the longer the life span, all things being equal. Battery weight is a simple indicator for the thickness of the lead plates used in a battery. The heavier a battery for a given group size, the thicker the plates, and the better the battery will tolerate deep discharges.


The followings are some types of batteries:

Flooded Lead Acid, Wet Lead Acid or flooded lead-acid batteries are the most commonly used batteries to store electrical power. These are available in vented types (most common), where water can be added, and also in sealed types, where water cannot be added.

Absorbed Glass Mat or AGM batteries utilize a fiberglass mat saturated with sulfuric acid. AGM batteries are also sometimes called "starved electrolyte” or "dry", because the fiberglass mat is only 95% saturated with sulfuric acid and there is no excess liquid. An AGM battery is cleaner and can be shipped without any hazardous material requirements. They are far superior for most uses, can take a fair amount of abuse and are non-spilling even when broken. The major disadvantage is a higher cost than a flooded battery, approximately 2 to 3 times. In cases where fumes and leakage are not an issue, the more economical choice is probably a flooded industrial lead-acid

GEL Cell or sealed lead-acid batteries are frequently selected in applications where batteries cannot be vented or cannot be mounted in an upright position. Gel cells are cleaner in the sense that they do not vent gasses like lead acid batteries. However, gel cells are more sensitive to charge voltage (and cannot typically be charged with an automotive type battery charger) since they cannot vent except in emergencies (which may cause irreversible damage). In addition, the gel cells are much more sensitive to higher temperatures and cannot tolerate being discharged for long periods of time relative to a flooded lead acid battery. Therefore, the charge on gel cells must be regulated properly. If using gel cells, follow the manufacturers’ recommended regulation set points. Gel cell batteries may require an external battery temperature compensated regulator. Due to the extra cost of gel celled batteries and the temperamental characteristics of these batteries, they are not recommended.

Nickel Cadmium or Nickel Iron batteries are generally used in extreme conditions. These batteries will perform at temperatures less than -40° C (-40° F). They are capable of delivering higher current and cycle deeper and more often than lead acid AGM and gel batteries. Nickel iron batteries can have a 20+ year life. Nickel iron is one of the most environmentally friendly batteries. However, nickel cadmium batteries contain heavy metals. The disadvantages of this type of battery are its high cost and its low-efficiency charge.