LEAD ACID BATTERIES
Using an electrolyte consisting of sulphuric acid, a battery can store impressive amounts of electrical energy in a relatively small space. This energy is stored in chemical form within lead grids mounted inside the battery. Currently, there are three common lead acid battery technologies: Flooded, Gel and AGM. All our systems use either Gel or AGM batteries and here is why.
- AGM stands for Absorbed Glass Mat, a newer type of battery construction that uses saturated absorbent glass mats. AGM batteries are sealed and therefore require no maintenance. This also means no acid spills, gassing, watering or an equalization process to contend with.
- Gel batteries use a thickening agent like fumed silica to immobilize the electrolyte. If, by chance, the battery container cracks or is breached, the battery will continue to function. As with the AGM battery, the Gel cell is sealed and user friendly as well.
- Flooded batteries are the most common lead-acid battery-type in use today. However, they do require maintenance on a regular basis. Along with the need to have the electrolyte solution topped up, specific gravity checks done with a hydrometer, an equalization process performed, they also need a specially built container or a separate ventilated room as they “off gas” (produce toxic fumes). Since the battery is not sealed, great care has to be used when working with these batteries as the electrolyte (sulphuric acid) will burn your skin!
More food for thought:
- Flooded cells can lose up to 12% per month due to self-discharge while AGMs and Gel cells lose only 1-3% per month.
- AGMs have a higher charge efficiency which allows you to recharge in less time. Flooded cells convert 15-20% of the electrical energy into heat instead of potential power. Gel cells typically lose 10-16% while AGMs as little as 4%.
- Lead acid batteries are good for wide temperature ranges
- Both Lithium & Lead Carbon (see following page) need a controlled environment not below freezing
- Lead acid batteries are good for cabin systems
- Lithium batteries are ideal for larger systems with 2 to 3 times longer life over Lead acid however they are more expensive
- We use the 10 hour discharge rate for battery calculations as this is the realistic amount of time it will take to discharge a battery. Some manufacturers use the 100 hour rate which we feel is not practical in real life situations.
- In our Solar Kits, we list both the Battery Capacity and the Daily Useable Capacity as no battery should be fully discharged