Mercedes benz battery not charging

Problem of Mercedes benz battery not charging can be happen due to may reasons like, faulty alternator, faulty battery, damage wiring harness of alternator and loos connection of main battery cable or broken main battery cable which is connected from one side on battery and other side is on alternator. Alternator is use to charge battery by producing DC voltage. In some models of mercedes benz alternator is not directly connected with battery.

There is a fuse box at left side in front of battery. That fuse box is connected with battery main cable, and all the other main positive wire of alternator, starter, power steering goes into them from this fuse box. In this fuse box there is a relay called 30G relay. This is use to actuate power supply from alternator to all the other components. Failure of 30G relay can create problem of no charging and so many other as it work as actuator.

Causes of Mercedes benz battery not charging :

  • Faulty alternator.
  • Loss connection of battery positive cable.
  • Faulty fuse box.
  • Also failure of 30G relay.
  • Blown fuse of alternator.

Symptoms :

  • Low battery problem.
  • Battery not charging issue.
  • Battery warning light will illuminate on cluster meter.
  • Also Car may not start due yo low battery.

How to trouble shoot :

  • First mechanic need to scan vehicle if there is any electrical problem which is causing no charging problem. If found any other problem accept alternator than repair that will solve problem.
  • In case of no battery charging check battery condition, check water level in battery, and age of battery. if water level in battery is not proper than fill it till require level. Than check positive cable which come from alternator to fuse box. If there is any damage on positive wire or there is any loose connection present. than repair or replace positive wire or make proper connection. till here all the think should be perfect so that you can move to the other think.
  • Than connect multimeter to battery there should above 12volt in no start condition, it should not less than 12volt. than start vehicle after starting vehicle there should be above 13.9 volt. After start if there is below 13.9 volt than it means that alternator is not charging battery. In this situation connect positive lead of multimeter direct on alternator after removing positive wire from alternator. There should be above 13.9volt, if it present then it means there is some loose connection between battery and alternator. If found any loos connection or damage at positive wire than make it perfect.
  • In case after removing positive wire from alternator, alternator is not producing above 13.9 volt. Than it means that alternator is faulty. In alternator there is a rotor, voltage regulator, rectifier check which one is faulty. When found faulty component replace that with new one.
  • When alternator is charging properly and there is no problem with positive wire than there might be some other problems. Like some time the negative terminal which is present at engine compartment to jump start. Change that negative terminal which will solve problem.
30g relay

Solution of Mercedes benz battery not charging :

  • Replace faulty alternator.
  • Repair or replace damage positive wire.
  • Replace faulty battery.
  • Replace broken negative terminal.
  • Solve any other problem if found

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