EZ Battery Reconditioning Method

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A battery in good condition may occasionally fail to crank the engine fast enough to make it start. In such cases, the battery may require charging.

All battery chargers operate on the same principle: an electric current is applied to the battery to reverse the chemical action in the cells. Never connect or disconnect leads with the charger turned ON. Follow the battery charger manufacturer's instructions. And, do not attempt to charge a battery with frozen electrolyte.

When using a battery charger, always disconnect the battery ground cable first. This will minimize the possibility of damage to the alternator or to electronic components. Otherwise, use a charger with polarity protection that prevents reverse charging.

The battery can be considered fully charged when all cells are gassing freely and when there is no change in specific gravity readings for more than one hour.

Fast Charging

Fast charging is used to charge the battery for a short period of time with a high rate of current. Fast charging may shorten battery life. If time allows, slow charging is preferred. Some low maintenance batteries cannot be fast charged.

1. Preparation for charging.

• Clean dirt, dust, or corrosion off the battery; if necessary, clean the terminals.

• Check the electrolyte level and add distilled water if needed.

• If the battery is to be charged while on the vehicle, be sure to disconnect both (-) (+) terminals.

2. Determine the charging current and time for fast charging.

• Some chargers have a test device for determining the charging current and required time.

• If the charger does not have a test device, refer to the chart below to determine current and time.

3. Using the charger:

• Make sure that the main switch and timer switch are OFF and the current adjust switch is at the minimum position.

• Connect the positive lead of the charger to the battery positive terminal (+) and the negative lead of the charger to the battery negative terminal (-).

• Connect the charger's power cable to the electric outlet.

• Set the voltage switch to the correct battery voltage.

• Set the timer to the desired time and adjust the charging current to the predetermined amperage.

4. After the timer is "off," check the charged condition using a voltmeter.

• Correct Voltage: 12.6 volts or higher.

If the voltage does not increase, or if gas is not emitted no matter how long the battery is charged, there may be a problem with the battery, such as an internal short.

5. When the voltage reaches the proper reading:

• Set the current adjust switch to minimum.

• Turn off the main switch of the charger.

• Disconnect the charger cables from the battery terminals.

• Wash the battery case to clean off the acid emitted.

Slow Charging

High charging rates are not good for completely charging a battery. To completely charge a battery, slow charging with a low current is required. Slow charging procedures are the same as those for fast charging, except for the following:

1. The maximum charging current should be less than 1 1/10th of the battery capacity. For instance, a 40 AH battery should be slow charged at 4 amps or less.

2. Set the charger switch to the slow position (if provided).

3. Readjust the current control switch from time to time while charging.

4. As the battery gets near full charge, hydrogen gas is emitted. When there is no further rise in battery voltage for more than one hour, the battery is completely charged.

• Battery Voltage: 12.6 volts or higher


Reserve Capacity Rating

20-Hour Rating

5 Amperes

10 Amperes

20 Amperes

30 Amperes

40 Amperes

75 Minutes or less

50 Ampere-Hours or less

10 Hours

5 Hours

21/2 Hours

2 Hours

Above 75 To 115 Minutes

Above 50 To 75 Ampere-Hours

15 Hours

71/2 Hours

3Vi Hours

21/2 Hours

2 Hours

Above 115 To 160 Minutes

Above 75 To 100 Ampere-Hours

20 Hours

10 Hours

5 Hours

3 Hours

2Vz Hours

Above 160 To 245 Minutes

Above 100 To 150 Ampere-Hours

30 Hours

15 Hours

71/2 Hours

5 Hours

31/2 Hours


Cleaning the battery will aid your visual inspection and reduce the possibility of current leakage. The battery case can be cleaned with a brush and diluted ammonia or soda solution. Avoid getting the solution in the cells. The battery terminals and cable connections can be cleaned with the cleaning tool (brush) made for that purpose. Remove all corrosion and oxidation, both common causes of high resistance.


When jump starting a dead battery with a booster battery, proper connections prevent sparks. First, connect the two positive terminals. Then, connect one end of the jumper cable to the negative terminal of the booster battery. And, connect the other end to a good ground away from the dead battery. If a spark occurs, it won't be near the battery.


If a battery requires replacement: use a cable puller to remove terminal clamps; unfasten the battery hold-down; lift the battery from its carrier with the proper tool; wash and paint corroded parts; replace any damaged parts of the hold-down, support tray, or cables; and select and install a battery of the proper size and capacity rating.

Taken with permission from the Toyota Basic Electrical Course #622,

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DIY Battery Repair

DIY Battery Repair

You can now recondition your old batteries at home and bring them back to 100 percent of their working condition. This guide will enable you to revive All NiCd batteries regardless of brand and battery volt. It will give you the required information on how to re-energize and revive your NiCd batteries through the RVD process, charging method and charging guidelines.

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