tonyC230

This goes out to a tech guy. I have searched and found lots about changing my own battery but I have a couple of questions. If the car is not running with the key out of the ignition then is there a problem taking the OEM battery out and putting in a new one. I know I will have to syn. the windows and panaroof but is there anything else to be concerned with? Can I connect a battery charger to the terminals while I dissconnect the battery to keep everything in memory or is it not a good Idea? I know I can take it to a dealer but I also know that the battery can be replaced for half the price of an OEM one. I have changed many in the past but this 02 C230 K seems to have lots of electronic stuff that my other cars don't have

mleskovar

Make sure you remove the negative terminal first.....and replace it on the new battery after the positive terminal is secured.

tonyC230

Thanks. I know about the negative terminal first but I forgot one thing. I have read about the rear sam unit. If the key is off and out of the ignition then disconnecting or unpluging the sam unit is the sam as diconnecting the battery. Someone has said that the sam unit might not power up again. That does not make sense to me that MB would build something like that. Can't see the harm in just taking the battery out and replacing it. I know to re-syn windows and roof but I don't want to have trouble with the sam unit. What does the tech guy do at MB. Does he put a power source to the terminals like a charger or back up battery or does he simply change the battery and re-syn stuff?

whoover

Yes, the dealer has an auxiliary power supply, but it's probably not worth it for you. Look in your manual. It has detailed instructions on what to do and what not to do, and what you need to do after replacing the battery. It's not going to be a problem as long as you heed their warnings and don't do anything stupid like disconnect the battery with the engine running.

mleskovar

All she did was replace the battery and resynch....it was more convenient for me to call MB roadside assistance to come out and give me a new battery when mine died.

AH1W-COBRA

hey tony,dont confuse the two.power supply provides a constant,clean,regulated voltage.a battery charger provides pulsed,dirty voltage designed only to recharge batterys.i noticed you questioned if a battery charger would work to maintain voltage.the answer is no,not safely.

tonyC230

Thanks for the info on a charger. I would like to know what the mechanic would use to maintain power to the system. I only have one MB Express location and it is over 40 miles away. The closer dealer damaged my car the last time I went there so, don't think I would like to take it there. The rear Sam unit as has been mentioned has me worried. Can't believe changing a battery is such a problem. My battery is working fine right now but would like to replace it because of age ( 02 ) not mileage ( 28,000 klm ) I store my car away for the winter and leave a battery maintainer on till spring but do not want problems. Unplugging the Sam unit would be the sam as disconnecting the battery. Don't understand the sam and powering it down or shutting it off and restarting it. Hey, what happens when it first goes into the car, ha ha.

tonyC230

I checked with a tech guy I know and he told me to just connect another battery to the spare terminal just under the red plastic cap and ground it anywere solid. Then remove the old one and put new one in. Only minutes to do the job were the dealer would charge 1/2 hour minimum for the same thing. Canadian price for the replacement battery is $222.50 plus tax of course. Think I'll shop around and probably get a better warranty