This page will deal primarily with Lead Acid batteries, there are other technologies on the market which I will touch on later.
First there are three kinds of lead/acid batteries:
- 1. Automobile batteries, including the big D8 diesel or tractors batteries;
- 2. Marine batteries;
- 3. Deep Cycle batteries or RV (recreational vehicle)
Understanding the difference between the battery types
Automobile batteries (SLI) are the most common because we use them to start our car. They are also frequently used incorrectly in Solar Power Systems. They can develop a lot of energy even in cold weather. The discharge time is limited to about 10 minutes. They have many thin lead plates that have a high rate of discharge to give the necessary energy to start the motor. They are not suitable for a long time use of a slow discharge rate like lighting or water pumping.
Marine batteries have the same construction as the car batteries except that their plates have their bottom taken or glued in epoxy to prevent breakage when the boat is knocked by the waves or with the vibration. Also they are not suitable for lighting or water pumps.
Deep Cycle batteries have their plates thicker and generally longer than the previous ones. This type of construction gives a longer and a slower rate of discharge necessary for lighting, or for powering a water pump. It is very important to note; if you do not see on the battery DEEP CYCLE OR RV, then it is not a deep cycle battery. These batteries are the only ones suitable for the good operation of electric lighting and water pumps.
We are mainly concerned with Deep Cycle batteries, these also come in various forms. Smaller batteries that look similar to car batteries and contain several cells in a tough plastic case, generate 6 or 12 Volts with capacities up to 200Ah. They are either flooded cell types, that require topping-up with distilled water; or sealed / gel types with an immobilised electrolyte.
Larger battery banks are usually made up of flooded 2V cells ranging in capacity from 100Ah to several thousand. Sealed types are also available.
Some flooded cell cell batteries using tubular positive plates instead of flat plates have a longer life.
Choosing a Battery
The main consideration when selecting a battery is the capacity. Equally it is important to consider where the battery will be located. A 24 volt (24V) battery array made up of 2 volt (2V) will occupy a considerable area and needs to be located in well ventilated room, preferably away from the normal living environment. Ideally the battery bank should be installed on its own, in a weather and frost protected, well ventilated shed or outbuilding. The ideal temperature is 20 deg C. and should not exceed 43 deg C. Batteries should be all of the same brand, age and amp-hour capacity.
Batteries are an expensive part of any investment in Solar Energy, proper storage and maintenance will ensure you get the maximum return on investment.
Our battery sizing form will assist you in calculating your battery requirements.For more information visit our addition pages on: