We are adding some sealed lead acid batteries to the site, both AGM (absorbed glass mat) and true Gel types, manufactured by Universal Power, headquartered in Texas. While we have kept our charger lines clear of Chinese made products (Taiwan is not the same as China), the Universals are made in China in a plant partially owned by Universal. This gives Universal a say that a simple customer/importer doesn't have. Their quality has been superb, and customer service outstanding. This is not the case with all imports.
Universal Power Group is a leader in competitively priced sealed absorbent glass mat (AGM) and gel technology. This new technology provides benefits compared to old technology wet batteries. They also boast one of the largest inventories of maintenance-free sealed lead-acid batteries in the nation, to which we have access.
The advantage of the sealed valve regulated design is that the battery needs no water additions, can be operated in any position, and can be used in close proximity to people and sensitive equipment. They are used in toys, medical equipment, mobility equipment, security, industrial equipment, consumer devices, and many other applications because of these features. The sealed batteries are DOT approved for air transport, and deemed non-hazardous. This makes them suitable for shipping around the country without hassles. It also allows travelers flexibility to carry them in luggage, or take a mobility chair or scooter abroad. All models we carry are designed to be cycled, dead if necessary, and give their rated service life, when properly maintained.
There are differences in construction, application, and maintenance between the AGM and Gel sealed lead acid batteries. First of all, they are both still lead acid types, though there is no free acid to leak, spill, etc. Some of the AGM types can be charged with the same charger used for flooded lead acid batteries, or used in a vehicle or piece of equipment with an alternator charging system. The Optima™ and Odyssey™ high performance batteries are examples of AGM construction, though they may be called dry cell, starved electrolyte, etc. True Gel cells, however, require specific charge profiles, particularly in the peak voltage settings of the charger. The term 'gel' has sometimes been used generically for all sealed lead acid batteries, and this practice is not correct, and causes confusion to consumers, and sometimes damaged/destroyed batteries. This makes it important to know which battery type you have, not trusting the salesman who sold you a 'gel' battery for your motorcycle (99% of the sealed power sports batteries are AGM).
The Gels were the first of the sealed lead acid type developed (in Germany, I believe), with the AGM coming later. The Gels tolerate temperature extremes a little better, but really only excel over an AGM in applications where they are cycled dead repeatedly and frequently, such as mobility wheelchair or scooter, or heavy duty golf cart applications. They give a few more cycles when treated this way. The Gels are more expensive though, and require a special charger or charger setting. Many applications are switching to AGMs.
There are small amp hour sealed lead acid batteries, on up to 250 amp hours and larger. The units under 30 amp hours are almost exclusively AGM construction. They usually say 'spill proof' or 'valve regulated', and 'sealed lead acid', and a few actually say AGM on them. The true Gels are usually over 30 amp hours, and have a 'G' in the model number, or actually say 'Gel' on them somewhere. If nothing else, they have a charging voltage recommendation of 14.0 to 14.2 volts (for a 12 volt battery). The AGM will have a charge voltage of 14.4 to 14.8 or even more. There are AGMs and Gels from around 30 amp hours on up.
These batteries, being sealed, cannot be tested with a hydrometer. A volt meter can tell something about the health or state of charge. We recommend anyone dealing with batteries or DC systems have a decent digital voltmeter. They aren't expensive. You can check battery charge, battery health, charger output settings, alternator output, wiring continuity, wire resistance, fuse continuity, solar panel output (voltage and current), parasitic drains, and many other electrical conditions with one.
Ask about quantity purchases, or battery sizes not found on the site. If it's a valid Universal part number, we can get it (case quantities).
Don't forget to check the tutorials for more on battery selection and charging, or contact us with specific situations, requirements.