Battery charge and discharge cycle

Battery charge and discharge cycle

What happens when solar batteries are charged and discharged?

When batteries are full the acid is at its strongest and at it’s weakest (diluted) when discharged. The process of charging and discharging a battery involves the transfer of sulphur from the liquid acid solution to the lead plates and vice versa. The acid solution is called the electrolyte. It’s not always a solutions and be in the for of a gel.

You might have heard the phrase ‘the batteries are sulphated’ and are therefore exhausted.  Batteries get sulphated when the sulphur has been on the plates for too long. If your the battery is frequently low in charge, or partially charged for extended periods of time they get sulphated. The longer the sulphur stays on the plates the harder it gets and the more difficult it is to remove it by charging.

This is why it’s vitally important that the source of energy (renewable or not) must be capable of charging the batteries on a regular basis. Loads or appliances connected must therefore not frequently fully empty them.

Getting the right power and type of battery for an off-grid installation is very important. This process is often referred to as system sizing and must take into account at leats the following factors:-

  • All the loads – Tasing that the system power
  • The hours the loads are used
  • Local insolation data (amount of sunshine)
  • The power output of the renewable energy sources
  • Temperature of the place the batteries are located

Batteries that are exposed to freezing temperatures they are more likely to freeze.  If the liquid (electrolyte) is a weak acid solution it will freeze at a another temperature. So keep your batteries charged to stop Jack Frost from rendering them useless  🙂

How to design your own solar power or lighting kit