After my entries regarding failing of Ctek and other superintelligent and expensive automatic chargers, quite many readers of my blog have asked me – what to do? What kind of charger to use? Do they have to spend more than EUR 1000 for a professional charger?


This is the time when I can say – use the simplest “old school” type charger! Something similar as in the picture:

Similar chargers are manufactured by many companies in the whole world. These chargers consist of 120/230VAC/13 .. 15VAC 50/60Hz transformer and bridge of diodes. And that’s it, no more complicated electronics you will find inside them!


I will mention several nuances, which is worth taking into consideration when purchasing such a charger:

  • the charger of 12/24V will be more appropriate as 6/12V because it will be more powerful;
  • if possible, chose the model with an automatic fuse – there will be no problem with replacing it in case of necessity;
  • ammeter of any type – obligatory. Only if the charger is equipped with the ammeter, you will see, if the charger gives energy to the car. The preferable scale of ammeter: above 5A (optimal: 6 .. 10A). The most powerful charger will be more efficient.


Below I will compile nuances, which have to be taken into account when charging (maintaining) the car with such a charger:

  • the charger has to be connected in the engine room to the intended clips, not directly to the battery. Only if the charger will be connected in the appropriate way, the IBS system will know, how much energy the charger has given to the battery during charging;
  • charger like this has no automatics, so – do not leave it connected to the car for a long time (longer than 24 hours);
  • if the car is not sleeping, this charger will not be able to charge the battery. While the car is awake, the amount of consumed energy will be larger than the one, which the charger is able to give to the battery! So – connect the charger and allow the car to “go to sleep”. Only when the car will “fall asleep”, the charging of the battery will start;
  • each “waking up” will consume the amount of charge of several hours. Accordingly – if the car will wake up for “only” several times, it can be, that even charging the battery during the night, the result at the morning will be not much better than it was at the evening. So – do not wake up the car! Lock it (so the car will go to sleep faster) and leave to charge;
  • if the car is equipped with a Keyless system, it will wake up if you will touch the handles or will close the key to the car. Make sure, that the car can “sleep” peacefully while charging;
  • leave the battery connected to the car. So the IBS system will know the state of charge. It makes sense to disconnect the battery only in case if you are leaving for a longer time (more than a month). For shorter periods the disconnection of the battery is not desirable;
  • if possible, in wintertime (when the temperature outside is below 0 oC), during charging keep the car in the garage – the highest the temperature, the most efficient is the chemistry of the battery, it better absorbs energy and works more efficient.

Remember – the indication of the charger’s ammeter indicates the energy, received from the charger, not the current, which flows in the connection of the battery (we are talking about the situation when the battery is connected to the car). If the car is awake, all energy is consumed to maintain the electronics of the car. Even more – E60/90 and newer cars can consume 15 .. 20A or even more when awake – a regular charger will not provide such current. The missing current will be taken from the battery – so: actually the battery will not be charged, but DIScharged. Take care, that the car “sleeps” during all time of the charging.