Rich electric Invertek CombiPlus, User Manual

Page: 36 / 128

Rich Electric Co. “CombiPlus” User Manual V7.19 Copyright 2009
Page 36
3.3 Gel:
Gel batteries have characteristics similar to AGM, except a silica additive immobilizes the electrolyte
to prevent leakage from the case. And like AGM, it is important to never exceed the manufacturer’s
maximum charging voltages. Typically, a gel battery is recharged in cycling applications from 14.1V
to 14.4V. Typical float voltage of 13.5~13.8v. The gel design is very sensitive to overcharging.
For both AGM and Gel batteries, the goal is for 100% recombination of gasses so that no water is
lost from the battery. True equalizations are never done, but a small boost charge may be needed to
balance the individual cell voltages.
Other Sealed Batteries:
Automotive and “maintenance-free” batteries are also sealed. However, these are not discussed here
because they have very poor lifetimes in solar / inverter cycling applications.
NOTE: Consult the battery manufacturer for the recommended solar charging settings for the
battery being used.
3.4 Flooded Batteries
Flooded (vented) batteries have been commonly used for many cycling solar inverter systems over
the years.
The advantages of flooded batteries are normally very cost effective. Flooded batteries can offer
good service life for deep cycle applications.
In cycling applications, flooded batteries benefit from vigorous charging and equalization cycles
with significant gassing. Without this gassing, the heavier electrolyte will sink to the bottom of the
cell and lead to stratification. This is especially true with tall cells. Hydrocaps can be used to limit
the gassing water loss. General monthly maintenance is normally required for flooded batteries to
maintain their water levels.
Note that a 4% mixture of hydrogen in air is explosive if ignited. Make certain the battery area is
well ventilated.
Special enclosure requirements are needed for flooded batteries. For more information on battery
bank enclosures and installations please refer to AUS/NZ standards AS 2676 & AS4086. Typically, a
gel battery is recharged in cycling applications from 14.6V to 14.8V. Float voltage are normally
around 13.2~13.8v. Typical equalization voltages for flooded batteries are from 15.3 volts to 16 volts.
However, a solar system is limited to what the solar array can provide. If the equalization voltage is
too high, the array I-V curve may go over the “knee” and sharply reduce the charging current.