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Battery Type
Lead acid
batteries are generally classified by application
(what they are used for) and by construction (how they
are made). The primary application is automotive in
which the battery is used for starting and lighting.
Deep cycle is another major application but is usually
broken down into more specific applications such as RV,
golf cars, renewable energy, and marine.
There are two popular construction types: flooded
batteries (wet) and VRLA batteries (Valve Regulated Lead
Acid). In the flooded types, the electrolyte is a
solution of sulfuric acid and water that can spill out
if the battery is tipped over. In VRLA batteries, the
electrolyte is suspended in a gel or a fiberglass-mat (AGM
technology), allowing these batteries to be mounted in a
variety of positions.
Before getting started, be sure to identify the
type of battery involved. This section addresses the
charging and maintenance for both flooded and VRLA
batteries. |
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Inspection
There are
many tools that may help in properly caring for and maintaining
batteries. Below is a list of basic items that Trojan recommends
for this task:
Recommended Equipment:
- Wrench
- Distilled Water
- Voltmeter
- Hydrometer
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- Post Cleaner
- Baking Soda
- Vaseline
- Goggles & Gloves
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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
great idea to start this routine when the batteries are first
received.
Inspection Guildlines:
1. Examine the outside appearance of the battery.
A. Look for cracks in the
container.
B. The top of the battery, posts, and connections
should be clean, free of dirt,
fluids, and corrosion. If
batteries are dirty, refer to the Cleaning section for the
proper cleaning procedure.
C. Repair or replace any damaged batteries.
2. Any fluids on or
around the battery may be an indication that electrolyte is
spilling, leaching, or leaking out.
A. Leaking batteries must be
repaired or replaced.
3. Check all battery
cables and their connections.
A. Look closely for loose or
damaged parts.
B. Battery cables should be intact; broken or frayed
cables can be extremely
hazardous.
C. Replace any cable that looks suspicious.
4. Tighten all wiring
connections to the proper specification (see below). Make
certain there is good contact with the terminals.
Proper Torque Values
for Connection Hardware:
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Flooded |
Automotive 50-70 in-lbs
Side 70-90 in-lbs
Wingnut 95-105 in-lbs
LPT 95-105 in-lbs
Stud 120-180 in-lbs
LT 100-120 in-lbs |
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VRLA |
Button 90 to 100 in-lbs
LT 100-120 in-lbs |
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WARNING: Do not overtighten terminals. Doing so can
result in post breakage, post meltdown, or fire. |
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Testing
Visual inspection alone is
not sufficient to determine the overall health of the
battery. Both open-circuit voltage and specific gravity readings
can give a good indication of the battery's charge level, age,
and health. Routine voltage and gravity checks will not only
show the state of charge but also help spot signs of improper
care, such as undercharging and over-watering, and possibly even
locate a bad or weak battery. The following steps outline how to
properly perform routine
voltage and specific gravity testing on batteries. This requires
a volt-meter and a hydrometer
(which we have available if you don't already own either).
I. Specific Gravity Test
(Flooded batteries only)
1. Do not add water at this time.
2. Fill and drain the hydrometer 2 to 4 times before pulling out
a sample.
3. There should be enough sample electrolyte in the hydrometer
to completely support the float.
4. Take a reading, record it, and return the electrolyte back to
the cell.
5. To check another cell, repeat the 3 steps above.
6. Check all cells in the battery.
7. Replace the vent caps and wipe off any electrolyte that might
have been spilled.
8. Correct the readings to 80o F:
Add .004 to readings for every 10o above 80o
F
Subtract .004 for every 10o
below 80o F.
9. Compare the
readings.
10. Check the state of charge using Table 1.
The
readings should be at or above the factory specification of
1.277 ± .007. If any specific gravity readings register low,
then follow the steps below.
1. Check and record voltage level(s).
2. Put battery(s) on a complete charge.
3. Take specific gravity readings again.
If any
specific gravity readings still register low then follow the
steps below.
1. Check voltage level(s).
2. Perform equalization charge. Refer to the Equalizing section
for the proper procedure.
3. Take specific gravity readings again.
If any
specific gravity reading still registers lower than the factory
specification of 1.277 ± .007 then one or more of the following
conditions may exist:
1. The battery is old and approaching the end of its life.
2. The battery was left in a state of discharge too long.
3. Electrolyte was lost due to spillage or overflow.
4. A weak or bad cell is developing.
5. Battery was watered excessively previous to testing.
Batteries
in conditions 1 - 4 should be taken to a specialist for further
evaluation or retired from service.
II. Open-Circuit Voltage
Test
For accurate voltage readings, batteries must remain idle (no
charging, no discharging) for at least 6 hrs, preferably 24 hrs.
1. Disconnect all loads from the batteries.
2. Measure the voltage using a DC voltmeter.
3. Check the state of charge with Table 1.
4. Charge the battery if it registers 0% to 70% charged.
If battery registers below the Table 1 values, the following
conditions may exist:
1. The battery was left in a state of discharge too long.
2. The battery has a bad cell.
Batteries in these conditions should be taken to a specialist
for further evaluation or retired from service.
TABLE 1.
State of charge as related to specific gravity and
open circuit voltage
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Percentage of Charge
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Specific Gravity Corrected to
80o F
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Open-Circuit Voltage
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6V
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8V
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12V
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24V
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36V
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48V
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100
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1.277
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6.37
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8.49
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12.73
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25.46
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38.20
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50.93
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90
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1.258
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6.31
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8.41
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12.62
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25.24
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37.85
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50.47
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80
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1.238
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6.25
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8.33
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12.50
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25.00
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37.49
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49.99
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70
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1.217
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6.19
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8.25
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12.37
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24.74
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37.12
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49.49
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60
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1.195
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6.12
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8.16
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12.24
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24.48
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36.72
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48.96
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50
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1.172
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6.05
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8.07
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12.10
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24.20
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36.31
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48.41
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40
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1.148
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5.98
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7.97
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11.96
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23.92
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35.87
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47.83
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30
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1.124
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5.91
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7.88
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11.81
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23.63
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35.44
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47.26
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20
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1.098
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5.83
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7.77
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11.66
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23.32
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34.97
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46.63
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10
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1.073
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5.75
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7.67
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11.51
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23.02
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34.52
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46.03
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Watering
(Flooded batteries only)
Flooded batteries need water. More importantly, watering
must be done at the right time and in the right amount or else
the battery's performance and longevity suffers.
Water should always be added after fully charging the
battery. Prior to charging, there should be enough water to
cover the plates. If the battery has been discharged (partially
or fully), the water level should also be above the plates.
Keeping the water at the correct level after a full charge will
prevent having to worry about the water level at a different
state of charge.
Depending on the local climate, charging methods,
application, etc. Trojan recommends that batteries be checked
once a month until you get a feel for how thirsty your batteries
are.
Important things to remember:
1. Do not let the plates get exposed to air. This will damage
(corrode) the plates.
2. Do not fill the water level in the filling well to the cap.
This most likely will cause the battery to overflow acid,
consequently losing capacity and causing a corrosive mess.
3. Do not use water with a high mineral content. Use distilled
or deionized water only.
CAUTION: The electrolyte is a solution of acid and water so
skin contact should be avoided.
Step by step watering procedure:
1. Open the vent caps and look inside the fill wells.
2. Check electrolyte level; the minimum level is at the top of
the plates.
3. If necessary add just enough water to cover the plates at
this time.
4. Put batteries on a complete charge before adding any
additional water (refer to the Charging section).
5. Once charging is completed, open the vent caps and look
inside the fill wells.
6. Add water until the electrolyte level is 1/8" below the
bottom of the fill well.
7. A piece of rubber can be used safely as a dipstick to help
determine this level.
8. Clean, replace, and tighten all vent caps.<
WARNING: Never add acid to a
battery.
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Cleaning
Batteries seem to attract
dust, dirt, and grime. Keeping them clean will help one spot
trouble signs if they appear and avoid problems associated with
grime.
1. Check that all vent caps are tightly in place.
2. Clean the battery top with a cloth or brush and a solution of
baking soda and water. When
cleaning, do not allow any cleaning solution, or other foreign
matter to get inside the battery.
3. Rinse with water and dry with a
clean cloth.
4. Clean battery terminals and the inside of cable clamps using
a post and clamp cleaner.
Clean terminals will have a bright metallic shine.
5. Reconnect the clamps to the terminals and thinly coat
them with petroleum jelly (Vaseline) to prevent corrosion.
6. Keep the area around batteries clean and dry. |
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Storage
Periods of inactivity can be extremely
harmful to lead acid batteries. When placing a battery into
storage, follow the recommendations below to insure that the
battery remains healthy and ready for use.
NOTE: Storing, charging or operating batteries on concrete is
perfectly OK.
The most important things to avoid:
1. Freezing. Avoid locations where freezing temperature is
expected. Keeping a battery at a high state of charge will also
prevent freezing. Freezing results in irreparable damage to a
battery's plates and container.
2. Heat. Avoid direct exposure to heat sources, such as
radiators or space heaters. Temperatures above 80° F accelerate
the battery's self-discharge characteristics.
Step by step storage
procedure:
1. Completely charge the battery before storing.
2. Store the battery in a cool, dry location, protected from the
elements.
3. During storage, monitor the specific gravity (flooded) or
voltage. Batteries in storage should be given a boost charge
when they show a 70% charge or less.
See Table 1 in the Testing Section.
4. Completely charge the battery before re-activating.
5. For optimum performance, equalize the batteries (flooded)
before putting them back into service. Refer to the Equalizing
section for this procedure. |
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Charger
Selection
Most deep cycle applications have some
sort of charging system already installed for battery charging
(e.g. solar panels, inverter, golf car charger, alternator,
etc.). However, there are still systems with deep cycle
batteries where an individual charger must be selected. The
following will help in making a proper selection.
There are many types of chargers available
today. They are usually rated by their start rate, the rate
in amperes that the charger will supply at the beginning of the
charge cycle. When selecting a charger, the charge rate should
be between 10% and 13% of the battery's 20-hour AH capacity. For
example, a battery with a 20-hour capacity rating of 225 AH will
use a charger rated between approximately 23 and 30 amps (for
multiple battery charging use the AH rating of the entire bank).
Chargers with lower ratings can be used but the charging time
will be increased.
Trojan among others, recommends using a
3-stage charger. Also called "automatic", "smart" or "IEI"
chargers, these chargers prolong battery life with their well
programmed charging profile. These chargers usually have three
distinct charging stages: bulk, acceptance, and float.
Battery Chargers |
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Charging
Charging batteries properly requires administering the
right amount of current at the right voltage. Most charging
equipment automatically regulates these values. Some chargers
allow the user to set these values. Both automatic and manual
equipment can present difficulties in charging. Tables 2 & 3
list most of the necessary voltage settings one might need to
program a charger. In either case the original instructions for
your charging equipment should also be referenced for proper
charging. Here is list of helpful items to remember when
charging.
1. Become familiar with and follow the instructions issued by
the charger manufacturer.
2. Batteries should be charged after each period of use.
3. Lead acid batteries do not develop a memory and need not be
fully discharged before recharging.
4. Charge only in well-ventilated area. Keep sparks or flames
away from a charging battery.
5. Verify charger voltage settings are correct (Table 2).
6. Correct the charging voltage to compensate for temperatures
above and below 80o F. (Add .028 volt per cell for
every 10o below 80o F and subtract .028
volt per cell for every 10o above 80o F)
Table 2. Charger Voltage Settings for Flooded Batteries
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System Voltage
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Charger Voltage Setting |
6V
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12V
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24V
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36V
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48V
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Daily Charge |
7.4
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14.8
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29.6
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44.4
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59.2
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Float |
6.6
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13.2
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26.4
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39.6
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52.8
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Equalize |
7.8
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15.5
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31.0
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46.5
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62.0
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Table 3. Charger Voltage Settings for VRLA
Batteries
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System Voltage
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Charger Voltage Setting |
12V
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24V
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36V
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48V
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Daily Charge |
13.8 - 14.1
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27.6 - 28.2
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41.4 - 42.3
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55.2 - 56.4
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Float |
13.5
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26.4
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39.6
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52.8
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7. Check water level (see the Watering section).
8. Tighten all vent caps before charging.
9. Prevent overcharging the batteries. Overcharging causes
excessive gassing (water breakdown), heat buildup, and battery
aging.
10. Prevent undercharging the batteries. Undercharging causes
stratification.
11. Do not charge a frozen battery.
12. Avoid charging at temperatures above 120o F.
Additional VRLA Charging Instructions:
1. Become familiar with and follow the instructions issued by
the charger manufacturer.
2. Verify charger has necessary VRLA setting.
3. Set charger to VRLA voltage settings (Table 3).
4. Do not overcharge VRLA batteries. Overcharging will dry out
the electrolyte and damage battery. |
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Equalizing
(Flooded batteries only)
Equalizing is an overcharge performed on flooded lead
acid batteries after they have been fully charged. It reverses
the buildup of negative chemical effects like stratification, a
condition where acid concentration is greater at the bottom of
the battery than at the top. Equalizing also helps to remove
sulfate crystals that might have built up on the plates. If left
unchecked, this condition, called sulfation, will reduce the
overall capacity of the battery.
Many experts recommend that batteries be equalized
periodically, ranging anywhere from once a month to once or
twice per year. However, Trojan only recommends equalizing when
low or wide ranging specific gravity (± .015) are detected after
fully charging a battery.
Step by Step Equalizing:
1. Verify the battery(s) are flooded type.
2. Remove all loads from the batteries.
3. Connect battery charger.
4. Set charger for the equalizing voltage (See
Table 2 in the Charging section).
5. Start charging batteries.
6. Batteries will begin gassing and bubbling vigorously.
7. Take specific gravity readings every hour.
8. Equalization is complete when specific gravity values no
longer rise during the gassing stage.
NOTE: Many chargers do not have an equalization setting so
this procedure can't be carried out. |
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Discharging
Discharging batteries is entirely a
function of your particular application. However, below is list
of helpful items:
1. Shallow discharges will result in a longer battery life.
2. 50% (or less) discharges are recommended.
3. 80% discharge is the maximum safe discharge.
4. Do not fully discharge flooded batteries (80% or more). This
will damage (or kill) the battery.
5. Many experts recommend operating batteries only between the
50% to 85% of full charge range. A periodic equalization charge
is a must when using this practice.
6. Do not leave batteries deeply discharged for
any length of time.
7. lead acid batteries do not develop a memory and need not be
fully discharged before recharging.
8. Batteries should be charged after each period of use.
9. Batteries that charge up but cannot support a load are most
likely bad and should be tested. Refer to the Testing section
for proper procedure.
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% Discharged
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100
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80
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60
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40
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20
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0
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% Charged |
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0
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20
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40
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60
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80
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100
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Battery Watering Diagram |
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