Partial State of Charge and Solar Telecom Batteries

by Terry Holtz

In off-grid telecom sites with energy storage, the solar batteries are usually sitting at a partial state of charge, meaning they are not fully charged, nor fully discharged.

Solar-powered telecom towers commonly have lead acid batteries for their energy storage systems. However, operating or even sitting idle at a partial state of charge is problematic for lead-acid batteries.  As lead acid batteries discharge, the active materials transform from lead to lead sulfate - it is this chemical reaction that provides the requested power.  

off grid solar telecom towerAn off-grid, solar-powered telecom tower. 

However, if those lead sulfate crystals are not transformed back (through charging) to lead in a short period of time, they become problematic for the life of the battery.  At state of charge below 100%, these lead sulfate crystals are present in the electrodes and, over time, build up and reduce the active surface area of the electrode.  This process, called ‘sulfation,’ results in a reduction of the battery capacity and a drastic shortening of the battery life. Sulfation is a very harmful reaction and is difficult to prevent if the batteries are not consistently fully charged. Unfortunately, if sulfation does occur, it is only partially reversible. For remote, solar-powered telecom towers without regular maintenance, it can be tricky to avoid leaving batteries at a partial state of charge.

So, what’s the best way to avoid this kind of situation? Try a different battery chemistry! For example, our Aspen batteries  use a completely unique chemistry called Aqueous Hybrid Ion™. Our batteries use a different materials, like a saltwater electrolyte,, that make sulfation impossible. In fact, hey are not affected by operating at partial state of charge at all.

Our Aspen batteries can be left at any state of charge (yes, even 0%— fully discharged) for an unlimited amount of time. This is a significant advantage for most applications, especially unmanned, unmonitored off-grid telecom stations that need energy storage. Plus, as an added bonus, there is no need to top-up the batteries at the end of the day using a generator, saving fuel and money for the operator.

Our  Aspen batteries are a smarter choice than lead acid for long-lasting, trouble-free energy storage.

Dive deeper. Discover the benefits of our solar batteries over traditional lead acid with this free white paper: 

telecom batteries white paper

Topics: Energy Storage, Commercial & Industrial, Telecom

Written by
Terry Holtz
Terry Holtz is an application engineer at Aquion Energy.
 

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