Accumulator batteries

2017.01.25

Explaining all the basics of accumulator batteries; how they work, what different type there are, which are suited for you project, etc.

Technically all batteries are accumulators, but not all accumulators are batteries. Being an essential component in solar panel technology, and with such a range of accumulator batteries available, it is important to do one's research. An accumulator battery, or energy accumulator as it is otherwise known, is able to store electrical energy and can be charged/discharged many times. Of course, it is important to highlight that not all batteries are the same and it is highly advisable to compare the characteristics of different types. All accumulator batteries have labels informing customers of their voltage and power storage capabilities, in addition to information about gel, valve-regulated lead acid batteries (VRLA) or absorbed glass mat technology (AGM).


The different battery types

Lead-Acid Batteries: These were first type of accumulator batteries invented, and they are still widely used to this day. Lead-acid batteries have good energy storage properties and provide high surge currents, however, they are bulkier when compared with NiMHs or lithium ions, but in static power storage banks this is not particularly significant. More often than not, lead-acid batteries require more maintenance, for example, checking electrolyte levels, and that there are dangers of gas production. But these issues are always being improved, for example many smaller lead-acid batteries now employ electrolytes in the form of a stiff gel rather than liquid acid. As an alternative to gel, others use AGM with damp electrolyte-soaked pads separating the battery plates. Gel and AGM batteries are normally completely sealed and any gasses produced are largely re-absorbed, but these types have a one-way valve and are categorised as VRLA. Sun Rui Electro-Tech, Hoppecke and Isofoton are some of the makers of lead-acid batteries suitable for use in energy storage banks. NiCd Batteries: Once upon a time Nickel-Cadmium batteries were the leading type of small rechargeable battery, offering a fair energy storage capacity and maintaining a steady voltage throughout their discharge cycle. They were also made in many of the popular consumer sizes but have generally been replaced by NiMH and lithium ions. NiMH Batteries: Nickel-Metal Hydride batteries offer high energy storage capacities, typically around two or three times that of the NiCd equivalents. However, fully charged NiMH batteries cannot be stored for long periods without recharging due to their relatively high self-discharge rate. Low self-discharge versions are sometimes available and these are normally labelled ""LSD"". These are widely used to power electric and hybrid vehicles. Lithium batteries: Lithium ions are some of the most advanced batteries currently available, offering a very high energy density in conjunction with low self-discharge properties. The main advantages of Li-ion batteries are their high-energy density, efficiency, long cycle life, no memory effect (loss of capacity due to incomplete recharge cycle) and they require little maintenance. They can, however, be quite expensive. Lithium ions typically come in one of three formats with various terminal options: pouch, cylindrical, and prismatic. Pouch types are usually used in small portable devices, such as cell phones, or in devices where low weight is paramount. Cylindrical forms are used to power medium-sized devices. Prismatic are customarily the largest, and are typically used in solar panels. Prismatic types usually have hard corrugated sides, which create air gaps between adjacent cells — an aid to cooling. Tesla Powerwall and Aleo are some of the leading makers of Li-ion batteries used in solar energy installations.


Finding the right battery

Any specialized battery labelled ""solar battery"", ""photovoltaic accumulator"" or ""solar energy accumulator"" is likely to be of the gel or AGM type and therefore maintenance-free. But with such a range of accumulator batteries on the market, it is certainly worth doing your research and comparing. A variety of battery types can be found on the Solarodo marketplace - take a look to find the most suitable option.