QuestionI have a Mercedes C ( second generation CDI ). Last week one of friends car ran out of battery and he asked me to help him start the engine of his car by connecting 200 Amp Booster cables to my battery. the + terminal of his car was accidentally connected to the - terminal of mine (or vice versa)and there had been a spark .Then we cahnged the terminals and he started running his engine. I used my Merceds C for a week ,everything alright, but yesterday when i stopped at a gas station,it did not work any more. A technician claimed that false connection might be the cause... is it true .may i take your opinion ?
thank you
AnswerOkul,
Depending on how long the terminals were reverse connected and what voltage was in his battery at the time, you could have had a spike on the system of your vehicle. It may also depend on whether the terminals was connect at his vehicle and were the spark occurred.
There is always a possibility of causing a spike through the charging circuit.
If the battery has on charge. I would disconnect the battery terminals (-) first then (+). Place the battery on a slow charger. Once fully charged reconnect the (+) then the (-).
Start the vehicle. You will need a voltage meter. With the vehicle running test the voltage at the terminals of the battery with meter Positive to positive, negative to negative. You should be getting about 13 volts form the alternator.
If the voltage is less that 12 volts, then you have to have the alternator repaired or replaced. If this vehicle has an external voltage regulator, it should also be replaced. The parts supply house can tell you if the voltage regulator is internal to the alternator on not. The reverse voltage may have burn out one of the diodes.
If the vehicle will not start, you may have a problem with the over voltage control relay. It is designed to keep from damaging systems on the vehicle. It may be located on the firewall and will have a fuse in the top. Check to make sure the fuse is OK.
Good Luck
Robert
