PowerStarŪ Brand AGM Sealed Lead Acid Batteries
10 Facts about AGM Batteries
1. AGM batteries were originally developed for the military and so are very robust and can take much more abuse than wet-cell or standard deep-cycle gel batteries. As the electrolyte is contained within the glass mats, there is nothing to leak or spill and they are relatively free from freezing damage.
2. As with other sealed batteries there is little to no maintenance with AGMs. Even more of an advantage is that most of them are 'recombinant'. What this means is that the oxygen and hydrogen combine inside the battery during charging cycles to form water - hence very little water loss and hydrogen emission. These batteries are therefore less hazardous than their counterparts.
3. AGM batteries can be stored in otherwise prohibited areas because of their advantages of no leakage and no fumes. Another advantage of this property is that they can be stored on end or on their sides if need be without damage.
4. The battery construction places the electrolyte in closer proximity to the active plate material. This enhances the efficiency of both discharge and charge cycles. Because of this, and because the internal resistance of the battery is very low they generally charge at a faster rate and to a higher capacity than non-AGM batteries. They can also take heavy discharge rates without damage and can take the occasional discharge below the recommended 50% of capacity rule.
5. AGMs have a very low discharge rate when stored for extended periods, and even if left to totally discharge in storage they can be quickly recharged back to over 95% of their capacity providing they have not been left too long in a discharged state. The advantage is, no flat battery after storing for extended periods (within reason of course).
6. Under normal operating conditions, a good service life of up to 5 years can be attained. With quality care and handling, managed discharge and charge even longer lifetimes are common. Some reports quote up to 10 years.
7. AGM batteries are quite a bit more expensive that conventional wet-cell and standard deep cycle. But if you measure this cost against their robustness, longer life expectancy and better performance, they still present as the best value for money over the longer term.
8. A 'normal' car alternator will only charge a wet-cell type battery to around 70-80% of its capacity. Because of its higher charging rates an AGM battery will just about fully charge and at a faster rate from the same type of alternator.
9. AGM batteries are capable of charging rates up to 75% of their rated ampere hour capacity. In some cases this can lead to damaged alternators or standard auto chargers that may be susceptible to the excessive heat generated when trying to deliver maximum amps. The good point though is that AGMs will charge at lesser rates and be quite happy doing that. But, if you are going to spend money on a quality battery then you should really be looking at buying a quality three-stage charger.
10. AGM batteries can handle a multitude of roles. They can be used as starting batteries, in deep cycle applications, or as standby batteries for critical powered systems. These reasons make them ideal for camping applications. They can also be connected in series or parallel banks providing for various terminal voltages and ampere capacities. I use two AGMs wired in parallel in my pop-up camper. They are charged via a three stage 'Smart' charger and I have never had an issue with them.