To determine the AH rating of a 12-volt battery

To determine the AH rating of a 12-volt battery

Battery preparation
To determine the AH rating of a 12-volt battery that has not been rated within ampere hours, first make sure that the battery is fully charged. If the battery is not new, you should use a battery charger to charge it, and then let it stand for several hours to remove the surface charge. Use a multimeter to measure the voltage between the two terminals of the battery. The voltage between the terminals of a fully charged 12-volt lead-acid battery should be at least 12.6 volts. In this case, you can start testing the battery.

Discharge test
Connect a resistor of about 1 ohm and 200 watts between the battery terminals. After the test, the multimeter should display about 12 amperes of current, but if this is not the case, please pay attention to the displayed current. To calculate the AH rating of a battery, you must determine how long it takes for the battery to discharge to approximately 50% capacity. To do this, monitor the voltage every hour for the next few hours and record it throughout the process.

The voltage should decrease by about 0.1 volt every two hours. If the rate of decrease is faster, the resistance provided by the resistor is too small and the current is too large to provide an appropriate estimate. You will need to connect a larger resistor to repeat the test process. After about 10 hours, the battery voltage should drop to about 12 volts. Write down the exact number of hours to calculate the AH rating of the battery.

Calculate AH
Once the battery power is reduced to about half, you can use a simple formula to calculate the ampere hour rating of the battery. Multiply the battery current (measured by resistance) by the time it takes for the voltage to drop to 12 volts to determine the half-charge rating. Multiply this number by 2 to get the true AH rating of the battery. For example, if your battery current is 12 amps, and the voltage reaches 12 volts after exactly 10 hours, the battery capacity is 12 x 10 x 2 = or the total rating is 240 AH.

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The internal resistance provides valuable information about the battery, as there will be a high reading at the end of life. Service personnel are required to take a snapshot of each battery or cell during installation and then measure the subtle changes that occur as the battery ages.

JET-AR01 battery internal resistance tester, is a portable battery tester, to test impedance online. It can test batteries' state of healthy (SOH) in very short time. It is a useful tools in daily maintenance.

Internationally, resistance test, also called impedance test, is widely applied in daily battery maintenance instead of voltage check, because resistance is important parameter to test battery quickly and accurately worldwide.

It is digital and multifunction which can quickly and accurately measure the battery running status. It can show and record multi-group battery cell voltage, internal resistance, interconnection resistance, etc., and also precisely judge battery’s condition (pass/warning/fail).

Key Functions

1. Online test the battery voltage, interconnection resistance.
2. Determines health of battery with pass/warning/fail.
3. Battery internal resistance and voltage out of range alarm.
4. All the battery test results are marked by group No., user can manage the data conveniently.
5. PC software analysis the battery according to the history data.

Key Features

• High precisely online testing, automatically switch the testing range in 0.000mΩ-99.999mΩ
• Great data storage capacity, 999 groups of test results (Max. 500 cell battery per group), 200 groups of setting parameter.
  • English Menu, 3.8-inch 320*240 LCD Display.
  • SD card can save data, and export data to PC to analysis the battery state.
  • Enhanced over pressure protecting function.
  • Self-recovery the over current protecting function.
  • Use the SOC chip to improve the tester stability.
  • Big capacity Lithium cell and AC 100V-240V power supply
  • Low battery indication.
  • Smart and portable, one person can finish all test, good at saving time and cost.
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• Powerful PC software for manage the testing data.
  1. Automatically analysis battery “bad” state.
  2. Building the history record base, describe the battery sate curve.
  3. Batteries contrastive analysis in the same battery pack.
  4. All batteries are administrated by different levels (excellent, good, medium, bad)