What Exactly is an AGM Battery?
This entry was posted on August 28, 2010.
Solar panels are a large investment. In order to have a properly working and efficient system, the system needs to have a good battery bank. A good battery bank will keep the system regulated, a constant power supply to the house, and be low maintenance. The initial investment for absorbent glass material (AGM) batteries is well worth the long term required maintenance costs. AGM batteries are a specific type of valve regulated lead-acid batteries (VRLA).
These specific type of batteries have several qualities over different batteries of the same size. The first and foremost being that they do not require watering. This means a low maintenance design construction and a safer battery all together. The term however, is slightly wrong. The name should be more like recombinant batteries. This is because of the process that happens within the battery. The oxygen created at the positive plate will largely recombine with the hydrogen created at the negative plate.
The Advantages of Using AGM Batteries
This design is really helpful when it comes to solar panels for several reasons. The design offers a lot more power for the size than traditional batteries. The AGM batteries have a high rate power capacity and a relatively short duration. These types of batteries can also be found in uninterpretable power supply applications. The specific power, or power density, of these batteries is exceptional. They can be charged and discharged rapidly. They also hold their charge for a long period of time due to their construction.
The AGM battery is called an absorbent glass battery because the electrolyte is absorbed into a material made from glass. It is hard to come up with a better name for it. The plates in these batteries come in either flat cells or cylindrical cells. Each are good for different things. The cylindrical can support weight better, so can have a purer lead, translating to higher power density. The rectangular ones are easier to work with in a series, which is what you will use for your battery bank. Therefore, the rectangular celled batteries should be used.
Why They Work So Well With Solar
So what makes them good for solar application? First, the voltage is the same for any standard battery, that means no special equipment or electrical know-how required. The internal resistance is lower than most batteries, so the battery does not produce nearly as much heat. They also have extremely high charge and discharge current limits. Beyond this, the self-discharge is low. So low that it is 1 to 3 percent every month. This means that if you go for a long period of time without sunlight to boost the system back up to power, the batteries will still retain a charge.
The only drawback to these special batteries is the cost. They can sometimes cost almost two to three times the amount of regular batteries. However, with the easy maintenance, the no spill and the power rating it is well worth the initial cost. For a battery bank, there is few batteries that can really compare to the AGM. That is unless of course you have access to the up and coming technology of the super capacitor. That is however a story for a different time.