Frequent short trips, stop-and-start traffic, sub-zero temperatures and additional electrical loads have reduced the starting power of your battery. To avoid a total battery failure, you should charge the battery in the spring and autumn at least. It is best to always combine external charging with changing the tyres. We will show you what to look out for when charging vehicle batteries.


Accucharger Sortiment

Frequent journeys over short distances, irregular driving profiles along with stop-and-start traffic, daily cold starts in the icy temperatures of last winter, additional electrical consumers such as heated seats and parking or rear window heating and many driving in economy mode have lowered the energy level of your battery start for start and journey for journey.

Treat your battery to an extra boost of external recharging now.


Which charger do I need to use?
As a general rule, fully automatic chargers (charging voltage limitation with 14.8 V) are well suited for charging the battery installed in a vehicle. These charging devices are fully automatic. Depending on the battery capacity, we recommend the following chargers:


We also recommend the battery tester so that you can periodically check the battery voltage. BBT DBA - Digital Battery Analyser

In general, the following applies for charging batteries:

It is essential that you check the open-circuit voltage with a battery tester or voltmeter. Please make sure to recharge the battery as soon as an open-circuit voltage limit of 12.5 V has been reached. To be able to measure the open-circuit voltage with a battery tester or voltmeter, you should wait approx. 5 hours after you have finished charging the battery (internally by alternator, externally by charger), or it has not been discharged for at least 1 hour.


Good to know: When maintaining the charge with a Banner Accucharger, the battery is periodically recharged with a small current after it has been fully charged, just to compensate for the battery's self-discharge! This is precisely why there is absolutely nothing to be said against a longer period of trickle charging when using a Banner Accucharger. Simply ideal for longer periods when the vehicle is not in use or for winter storage.

In start-stop cars it is essential to observe the following
If recuperation is also operated in the start-stop vehicle (recovery of braking energy), the AGM or EFB battery works artificially at a lower state of charge of approx. 70% (SOC State Of Charge 70%). In older cars without start-stop function, the battery was always charged to 100% by the alternator. A charge deficit can occur relatively quickly in the start-stop-car and lead to partial or full discharge, even with an almost new battery, and starting problems are then naturally pre-programmed. 


Please bear in mind: Especially in winter operation, below 0 degrees Celsius ambient temperature, the battery hardly absorbs any more charging current. At the same time, many power consumers are in operation, such as the rear window heater, seat heater, auxiliary heater and some others more! We are now completely ignoring the Economy (ECO) driving mode, which partially reduces the charging voltage to approx. 12.3V!

SORRY, no more battery is charged in driving mode!

Video: Autobatterie richtig laden
Banner HOW TO: Correctly recharge your car battery with the Banner Accucharger 6A Recovery

Correctly recharge your car battery with the Banner Accucharger 6A Recovery

  • Attaching the Accucharger in the car

    • Before charging, check the electrolyte level and, if necessary, fill up desalinated or distilled water to the max. acid residue mark or 15 mm above the upper edge of the plate.
    • The battery screw connections must not be kept open during charging and it is best to close them again.
    • Running Bull AGM/BackUp: AGM batteries must not be opened. It is not possible or necessary to measure the acid density or top up with distilled water.
  • What to look for when loading!

    Connect the red clamp to the positive terminal and black clamp to the earth terminal*.

    • This is particularly important in modern vehicles due to the battery sensor, as otherwise the sensor cannot recognise the charging current correctly and may generate an error message. Once again: The charging current must run via the sensor, otherwise the control unit does not know that the battery has been charged and in the worst-case scenario will issue a message saying “Restart not possible”.
    • *The recommendation has been made before, that time due to the formation of sparks when coming into contact with the negative terminal. (Earth = metallic smooth point away from the battery).

  • Connect the Accucharger to the 230 V socket.

    • Do not switch on the charger until the battery has been connected.
    • We recommend a charging current of one tenth of the capacity (e.g. 44 Ah / 10 = 4.4 A charging current).
    • For automatic chargers, such as the Banner Accucharger, this is set automatically.
  • Charging starts automatically

    • The Accucharger automatically charges the battery with the recommended charging current.
    • During charging, the temperature of the acid must not exceed 55 °C. If this is exceeded, you must stop charging the battery. 
    • Display of battery charge in percent.

    • When the battery charge is at 100%, it automatically switches to charge retention mode.

    • Ensure good ventilation when charging.

  • Unplugging and disconnecting the Accucharger

    • The battery is fully charged when the current drops to 0 or no longer decreases or the automatic charger switches off itself. 
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Accucharger 3A
Banner Accucharger – for professional battery charging and charge retention. Simple, fully automatic, safe and fast.
überladung autobatterie, starterbatterie

This is exactly what an automatic charger of the Banner Accucharger series prevents!
Under- or overcharging of a battery as shown in the picture.


What happened here?
Charging and subsequently overcharging of a discharged start-stop battery in a garage, unattended overnight of course, with a so-called workshop charger with W-characteristic (falling current with rising voltage = transformer characteristic).


The workshop charger has only one voltage limitation (often only at approx. 15.5V !). The voltage (in volts) rises continuously during the charging process, while the charging current (in amperes) continues to fall. Charging must always be stopped manually in time to prevent overcharging, overheating and excessive gassing of the battery!


PS: The battery also lacks a degassing hose for the correct and safe discharge of oxyhydrogen!


The optimum charging voltage briefly noted, for external chargers.


Please note for AGM batteries:

  • Maximum charging voltage must not exceed 14.8V (voltage constant), the gassing voltage is approx. 14.6V! Therefore, always check the design of the alternator in the vehicle.
  • Only use voltage-regulated chargers with at least IU characteristic and AGM/GEL charging programme.

Please note for conventional and EFB batteries (Ca batteries):

  • Maximum charging voltage must not exceed 14.8V! Optimum charging voltage for all calcium batteries (Ca) is approx. 14.6 - max. 14.8V, the gassing voltage is approx. 14.6V. Gassing is good for electrolyte circulation, counteracts possible acid stratification, but means some water loss!
  • It is best to use voltage-regulated chargers with at least an IU characteristic.

In general, the following applies: 

Fully automatic chargers (charging voltage limited to 14.8 V) are well suited for charging the battery installed in a vehicle. If your charger has an automatic mode with voltages >14.8 V, the battery must be disconnected from the on-board electronics or removed from the vehicle altogether. In the worst case, the installed control units could be destroyed by overvoltage, the resulting damage would be enormous.

Please pay attention to the type of charger. Valuable tips on charging the vehicle can be found in most of the operating instructions issued by the vehicle manufacturer or the charger manufacturer.

All values quoted refer to a room temperature of +25 °C. Caution: Temperature compensation in case of deviation. 


Please note:

If the vehicle is also used for recuperation (recovery of braking energy), as is the case in many start-stop car models, the AGM or EFB battery works artificially at a lower state of charge (SOC State Of Charge at approx. 70%). An external periodic 100% full charge is really optimal!


BMW batterie nachladen
Recharging process in the car and battery not installed in the engine compartment! In some car models, the battery is installed in the boot, less frequently in the interior or passenger compartment. The battery terminals are now increasingly difficult to reach due to a clipped-on fuse box or similar, which is precisely why these cars have a positive and negative jump start connection in the engine compartment. Caution! If available, it is best to use the jump start connections in the engine compartment for recharging (and jump starting). So always use the red positive contact from the jump start connection in the vehicle requiring assistance for the charger, not the positive terminal of the battery, then use the metallic negative contact from the jump start connection in the vehicle requiring assistance - if not available then simply connect to earth. (Ground = bare metal point in the engine compartment).
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