Battery Maintenance
CAUTION: Always wear protective clothing,
gloves, and goggles when handling batteries, electrolyte, and charging your
battery.
Batteries should be
carefully inspected on a regular basis in order to detect and correct potential
problems before they can do harm. It is a good idea to start this routine when
you first establish your battery bank. AGM batteries have no accessible
electrolyte that can be drawn from the fiberglass mat and are also usually
sealed (VRLA**) therefore cannot be tested for specific gravity testing.
However resistance and also voltage can be used if the AGM batteries have
had absolutely no electrical loads
or charging for 4+ hours. Flooded lead-acid batteries are easy to test.
Inspection Guidelines:
lead acid battery
Examine the outside appearance of the battery:
- Look for cracks in the
container.
- The top of the
battery, posts, and connections should be clean, free of dirt, fluids,
and corrosion. If batteries are
dirty, a weak solution of household baking soda and water can be used to
neutralize any spilled acid. Make sure no solution enters the vent cap and
gets into the battery.
- Ensure that battery tops and
terminals are dry and clean after each maintenance.
- Replace damaged batteries.
Any fluids on or around the
battery may be an indication that electrolyte is spilling, leaching, or leaking
out. Leaking batteries must be replaced unless the spill is due to overfilling
the battery.
Check all battery
cables and their connections.
- Look closely for loose
or damaged parts.
- Battery cables should
be intact; broken or frayed cables can be extremely hazardous.
- Replace any cable that
looks suspicious.
- I use a laser thermometer to
check connections and individual cells as well.
Maintenance
State of Charge
Charge% |
Specific
Gravity |
100% |
1.255 – 1.275 |
75% |
1.215 – 1.235 |
50% |
1.200 – 1.180 |
25% |
1.165–1.155 |
0% |
1.130-1.110 |
Battery Ailments and Problems
Stratification: Heavier
charged ions within a lead acid battery sink to the bottom of the cells.
This leaves discharged electrolyte or diluted electrolyte at the top. The
results is oxidization at the top of the plates and accelerated corrosion at the
bottom of the cells due to higher acid concentration.
Sulfation: The
depositing of lead sulfate crystals on the plates occurs as the battery is
discharged and permanently reduces the capacity of the
battery. Deep discharging of the batteries can cause the sulphate to expand the
negative lead plates separating the lead from the grid, or shorting it
permanently damage the cell. Batteries, which remain partially, discharged
for extended periods of time develop "memory" of the reduced state of charge due
to sulfation.
Sulfation accounts for approximately 85% lead-acid battery failures.
Avoiding
extended periods of deep (>20%) discharge will reduce sulphation.
Battery RX for flooded acid cells
Stratification and lead sulphate
may be partially removed from cells via a controlled equalization charge.
During equalization a 2.35 - 2.4 Volt per cell is charge is applied to the
battery.
Equalization is indicated when:
- after extended periods of
deep discharge
- if any cell has a
variation of more than 0.05 V from the battery voltage
- when temperature corrected
specific gravity is 0.010 below the full charge value or differs ±
SG 0.015 from the other batteries within the array.
REMINDER:
Tighten all wiring
connections to the
proper specification. Make certain there is good clean contact with the
terminals.
WARNING: Do not over tighten terminals.
Doing so can result in post breakage, post meltdown,
or fire.
** VRLA = valve regulated lead acid
|