Starter batteries – testing, charging, bypassing and replacements

11. Nov 2021 | Technology + Products

An annoying situation that many drivers are unfortunately familiar with: The vehicle will not start. Fortunately, there are various ways to solve the problem or avoid it from the outset.

Charging, bypassing or replacement: The right solution for a discharged battery

If the vehicle will not start because the battery is discharged, this does not automatically mean that it has to be replaced. Battery chargers can often help. It is essential to ensure that the charger is suitable for the battery type in question. Depending on the battery type, different charging curves and end voltages must also be selected. Older chargers should no longer be used, as these are usually not regulated. This could lead to overcharging of the battery, causing outgassing and can lead to an oxyhydrogen effect.

To charge a starter battery, the Flash CS120 battery charger (Item no.: 95950005) can be used. To do this, first set which battery type is available and how many amperes are required. The device is also suitable for external power supply during diagnostic work or software updates. It compensates the power consumed by the control and diagnostic device and supplies the used quantity.

The classic scenario: Starting aid by a donor vehicle

Of course, a vehicle with a discharged battery can also receive a starting aid from a donor vehicle. A jumper cable with a diameter of at least 25 mm2 is recommended. It should also be ensured that the terminals on the cable ends are well insulated so that no short circuit is caused if they should slip off. A jumper cable with overvoltage protection can also provide additional safety, as it protects the battery against excessively high electrical voltages and thus prevents damage to the electronics. It is also important to connect batteries to the same rated voltage and similar capacity.

If all else fails: What should be taken into account when replacing the starter battery

If an empty starter battery cannot be brought back to life with the appropriate charger or starter battery, it must be replaced. There are also a number of things that need to be taken into account when replacing them. When the battery is removed, the entire vehicle electrical system must always be de-energized. This means that settings such as radio codes or seat memories are lost, which can lead to a significant number of error messages when a new battery is connected. To prevent this, a buffer battery can be used during removal, which continues to supply the central electrics with power. A starting aid device such as the Reanimator (Item no.: 95980802/-806/-807) is also suitable here. The battery booster ensures a constant power supply and can also act as a starting aid.

If a battery needs to be replaced, it is also important to note that the old battery must be replaced by an equivalent battery. However, it is possible to switch to a more powerful battery at any time.

Initially, battery management systems usually have to detect that a new battery has been installed. So they have to be taught again. The requirements for this differ, however, depending on the manufacturer and many workshops do not have the correct equipment for all situations. To resolve this problem, Herth+Buss offers a simple solution in the form of the Diagnosis on Demand diagnosis unit (Item no. 95990401). Contact with the Herth+Buss technology team is established via the device. The team them takes on the work of the OE workshop and teach the battery. This saves both time and money.

Forewarned is forearmed: Check starter batteries in good time

To ensure that the battery works properly, it should be checked at least once a year, particularly before the winter months. This can be carried out using the CrankPrint testing unit (Item no.: 95972081), for example. This unit is suitable for checking the start and charging system in the vehicle and determining the starting capability. The most important test values that should be considered with a device like this are SOH and SOC. SOH stands for State of Health and indicates the general state of the battery, i.e. the starting capability, while the SOC, which stands for State of Charge, indicates the charge status. The battery power can be specified in both volts and amps. The CrankPrint testing unit is suitable for both AGM, spiral, flat plate, gel and conventional wet-cell batteries, as well as for start-stop batteries.

Another important test variable is the internal resistance of the battery. This should be as small as possible so that the power generated by the battery is supplied completely to the consumers. Voltages such as those can be measured using the multimeter (Item no.: 95980775), for example. The advantage: It can also be used for many other applications, as it can measure additional electrical variables such as frequencies or temperatures in addition to voltages.