USER MANUAL
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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 dis-
cussed here because they have very poor lifetimes in renewable cycling applications.
NOTE:
Consult the battery manufacturer for the recommended charging settings for the
battery being used.
7 .2 Flooded Batteries
Flooded (vented) batteries are preferred for larger cycling renewable systems.
The advantages of flooded batteries include:
• ability to add water to the cells
• deep cycle capability
• vigorous recharging and equalization
•
long operating life
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.
Note that a 4% mixture of hydrogen in air is explosive if ignited. Make certain the battery
area is well ventilated.
Typical equalization voltages for flooded batteries are from 15.3 volts to 16 volts. However, a re-
newable system is limited to what the renewable system 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.
Lead-Calcium:
Calcium batteries charge at lower voltages (14.2 to 14.4 typically) and have strong advan-
tages in constant voltage or float applications. Water loss can be only 1/10th of antimony
cells. However, calcium plates are not as suitable for cycling applications.
Lead-Selenium:
These batteries are similar to calcium with low internal losses and very low water consump-
tion throughout their life. Selenium plates also have poor cycling life.
