Simple Steps for Longer Battery Life
The key to achieving optimum performance and long life is a solid battery maintenance program using the simple procedures outlined here.

Recommended Equipment

  • Wrench
  • Distilled water
  • Voltmeter
  • Hydrometer
  • Post Cleaner
  • Baking Soda
  • Petroleum Jelly
  • Goggles and gloves

Caution: Always wear protective clothing, gloves and goggles when handling batteries and electrolyte.

 

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 Recreational Vehicle, 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
Batteries should be carefully inspected on a regular basis in order to detect and correct potential problems before they can do harm.

Inspection Guidelines

  1. Examine the outside appearance of the battery.
  • Look for cracks in the container.
  • The top of the battery, posts and connections should be free of dirt, fluids and corrosion.
  • Repair or replace any damaged batteries.
  1. Check for any fluids on or around the battery.
  • Any fluids on or around the battery may indicate that electrolyte is spilling, leaching or leaking out.
  • Leaking batteries must be replaced.
  1. Check all battery cables and 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.
  • Tighten all wiring connections to the proper specification. Make sure there is good contact with the terminals.

Proper Torque Values for Connection Hardware:

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
VRLA Button 90 to 100 in-lbs
LT 100-120 in-lbs

Warning: Do not over-tighten terminals as this 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.

Specific Gravity Test
(Flooded/Wet 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 80° F:
    Add .004 to readings for every 10° above 80° F
    Subtract .004 for every 10° below 80° 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 equalisation charge. Refer to the Equalising 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.

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.

State of charge as related to specific gravity and open circuit voltage

Percentage of Charge

Specific Gravity Corrected to
80° F

Open-Circuit Voltage

6V

8V

12V

24V

36V

48V

100

1.277

6.37

8.49

12.73

25.46

38.20

50.93

90

1.258

6.31

8.41

12.62

25.24

37.85

50.47

80

1.238

6.25

8.33

12.50

25.00

37.49

49.99

70

1.217

6.19

8.25

12.37

24.74

37.12

49.49

60

1.195

6.12

8.16

12.24

24.48

36.72

48.96

50

1.172

6.05

8.07

12.10

24.20

36.31

48.41

40

1.148

5.98

7.97

11.96

23.92

35.87

47.83

30

1.124

5.91

7.88

11.81

23.63

35.44

47.26

20

1.098

5.83

7.77

11.66

23.32

34.97

46.63

10

1.073

5.75

7.67

11.51

23.02

34.52

46.03

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Watering (Flooded batteries only)
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.

Flooded batteries need water. But more importantly, watering must be done at the right time and in the right amount or else the battery's performance and longevity suffers.

General watering instructions:

  1. Add water, never acid, to cells (distilled water recommended)
  2. DO NOT OVERWATER
  3. For fully charged standard deep cycle batteries, add water to the level of 1/8 below bottom of vent well (see diagram A below)
  4. For fully charged Plus Series batteries, add water to the maximum water level indicator (see diagram B below)
  5. If the batteries are discharged, only add water if the plates are exposed. Add just enough water to cover the plates, then charge the batteries. Once fully charged, add water to the proper level indicated above
  6. After watering, secure vent caps back on batteries
Diagram 1    Diagram B
diagram A diagram B

Add water to 1/8" below bottom of the   Add water to the maximum water level indicator.
vent well.

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Equalising (Flooded batteries only)
Equalising 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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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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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. The tables below 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 (See Table below).
  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)
  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.

Charger Voltage Settings for Flooded Batteries

  System Voltage
Charger Voltage Setting

6V

12V

24V

36V

48V

Daily Charge

7.4

14.8

29.6

44.4

59.2

Float

6.6

13.2

26.4

39.6

52.8

Equalize

7.8

15.5

31.0

46.5

62.0


Charger Voltage Settings for VRLA Batteries

 

System Voltage

Charger Voltage Setting

12V

24V

36V

48V

Daily Charge

13.8 - 14.1

27.6 - 28.2

41.4 - 42.3

55.2 - 56.4

Float

13.5

26.4

39.6

52.8

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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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 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.

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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.
% Discharged

100

80

60

40

20

0

0

20

40

60

80

100

% Charged

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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.
  4. Completely charge the battery before re-activating.
  5. For optimum performance, equalise the batteries (flooded/wet) before putting them back into service. Refer to the Equalising section for this procedure.
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