Which Tests to be performed on your motorcycle battery?
Voltage and Specific Gravity
All batteries can be tested with a resistive load test, either electronically with a special tester that measures internal resistance, or with a digital voltmeter. Batteries with removable caps can also be tested for specific gravity (SG) with a hydrometer. A fully charged battery at rest should read about 12.66 volts, with an SG of 1.265. A 75% charge yields 12.4 volts or 1.225 SG. A 50% charge yields 12.2 volts or 1.155 SG. And 11.7 volts or 1.120 SG indicates that the battery is fully discharged. Differences in SG greater than 0.050 between cells mean that the battery is worn-out.
Capacity test is the only way to get an accurate value on the actual capacity of the battery. While used regularly it can be used for tracking the battery’s health and actual capacity and estimating remaining life of the battery. When the battery is new its capacity might be slightly lower than specified. This is normal. There are rated capacity values available from the manufacturer. All batteries have tables telling the discharge current for a specified time and down to a specific end of discharge voltage. Table below is an example from a battery manufacturer
Impedance, an internal ohmic test, is resistance in AC terms. With regard to DC battery systems, impedance indicates the condition of batteries. Since it tests the condition of the entire electrical path of a battery from terminal plate to terminal plate, impedance can find weaknesses in cells and intercell connectors easily and reliably. Basically, impedance test is determined by applying an AC current signal, measuring the AC voltage drop across the cell or intercell connector and calculating the impedance using Ohm’s Law. In practice, not only is the AC voltage drop measured but so is the AC current. The AC current is measured because of other AC currents in a battery that are additive (subtractive). Other AC currents are present from the charger system. The test is performed by applying an AC test signal to the terminal plates. Then measure both the total AC current in the string and the voltage drop of each unit in the string by measuring each cell and intercell connector consecutively until the entire string is measured. The impedance is calculated, displayed and stored. As the cells age, the internal impedance increases as depicted .
It is well known that low temperatures slow up the internal chemical reactions in any battery; the degrees of reduced performance vary according to the technology. For example, at temperatures around freezing, a VRLA may need capacity compensation of 20%. The lead-calcium cell using 1.215 specific gravity acid will require a doubling of capacity, while the Ni-Cd will need about 18% increased capacity