The so-called gel batteries, also referred to as AGM or VRLA, are lead-acid and, in terms of the charging method, differ little from conventional ones with liquid electrolyte. But at the same time, they are low-maintenance.
Instructions
Step 1
Remember that lead gel batteries require almost the same safety precautions for use as conventional batteries. They can release hydrogen when charged, although this is unlikely to happen. Therefore, next to a charging battery (even if it is installed inside, say, an uninterruptible power supply or a cash register), you must not smoke, use an open fire, or any spark sources. Under no circumstances should AGM batteries be disassembled or short-circuited. However, unlike conventional lead-acid batteries, they can be operated in any position, not just vertical.
Step 2
Since the capacity of a gel battery is usually small, never use a car charger to charge it. They stabilize the charging current too high.
Step 3
The simplest way to charge an AGM battery is to use an uninterruptible power supply as a charger, which is designed to use the battery with the same parameters as the one you intend to charge. Purchase a used source that has damaged its own battery. With a de-energized and switched off source, connect to it instead of the standard battery the one that you want to charge, observing the polarity. Remember that in most of these devices, the charging circuit is galvanically connected to the mains, so do not touch any wires while charging. The device will tell you when charging is complete.
Step 4
When charging an AGM battery from a stable current source (not a stable voltage!), Use the same method as for a conventional lead-acid battery. First, hold the battery under a current equal to one tenth of its capacity until the voltage at its terminals equals 2.4 V per one can (for example, if there are six cans, it is 14.4 V). Then reduce the current to one twentieth of the capacity and hold it under that current for another two hours. If the capacity is expressed in milliampere hours, the current after recalculation will be expressed in milliamperes, and if the capacity is expressed in ampere-hours - in amperes.
