The lowdown on battery technology


Critical to any energy storage system is the battery itself. So what technologies are available and what are their pros and cons? Lance Turner takes a look inside the technologies available now and what’s in the offing.

IT SEEMS that almost every day a new domestic energy storage system is released onto the market. While manufacturers concentrate on the latest features like compatibility with existing systems, system monitoring, integrated inverters and even programmability, very little is mentioned about the actual storage medium itself.

What makes one battery better than another for a particular use, and which technology should you be looking at for your energy storage system needs? Let’s look at the current options in a bit more detail, including advantages and disadvantages of each, and then look at some newer technologies available now that you may not have seen.


This old faithful is the mainstay of the home energy storage industry. Lead-acid batteries have been in use for over a century and are a tried and proven technology.

They consist of plates made of spongy lead (negative plate) and lead dioxide (positive plate), with sulphuric acid as the electrolyte. During discharge, both plates are converted to lead sulphate, and the discharge reaction produces water which dilutes the sulphuric acid, changing its specific gravity. This change in specific gravity is what allows you to measure a flooded-cell lead-acid battery’s true state of charge using a hygrometer.

Lead-acid batteries have several advantages:

  • reasonable resistance to overcharging
  • lower cost than many other technologies
  • readily available
  • almost 100% recyclable
  • almost all inverters and charge controllers are lead-acid compatible
  • widespread knowledge of the technology in the industry.

They also have disadvantages, including:

  • low energy density, which means high weight per unit of storage
  • can’t be regularly deep cycled without reducing lifespan
  • primary reactive materials are toxic and corrosive
  • can produce explosive hydrogen gas when charging
  • can’t be stored partially discharged without damage—must be fully charged regularly to prevent sulphation (where permanent lead sulphate crystals form on the plates)
  • Peukert effect—effective capacity reduces with increasing discharge rate.

The full article looks at currently available battery technologies in detail, including:

  • lead-acid
  • lithium ion
  • flow
  • salt water
  • metal-air
  • molten salt

Read the full article in ReNew 137.