Bureaucrat, staff, administrator
4,335
edits
Changes
m
→Flooded or Sealed
Sealed batteries are just that, and they require no topping up. They use gel or absorption glass mat (AGM) to immobilize the acid solution. Unlike flooded batteries, they are not prohibited from air shipment. Gel batteries use a thickening agent like fumed silica to immobilize the electrolyte.
AGM batteries were originally developed for use in aircraft. In AGM batteries a fine fibreglass mat between the lead plates absorbs and immobilizes the acid. This makes the acid more available, enhancing the reaction between the acid and the plates. Consequently AGM batteries can be discharged and recharged at higher amperages than other types of construction.<ref>DC Battery Specialists, http://www.dcbattery.com/agmtech.html</ref> They are also resistant to vibration, operate in any position and will survive sub-mergingsubmerging.
Gels and AGMs have a lower internal resistance, losing only 1-3% per month due to internal discharge. Gel cells lose 10-16% to heat during charging while AGMs lose as little as 4%, meaning that the charging system can be smaller.