Jj james

I'm new here sure could use some help my wife's 2005 c230 seemed like battery loosing power7yrs old put new one in went down pulled alt had cked was bad said rotor was dead traded in for rebuilt one didn't tell me there were any choices charged batt car will not crank over makes small noise ??????

speedracer.eric

The issue I'm having is that the voltage seems to go all over the place when I start driving, or the RPM changes. When the car idles, it seems to be fine for a while @ around 13.5V. Then I start driving around the neighborhood and it drops to 11.7V or so. It doesnt come back up every time I stop, but most times I came to a stop, the voltage went back up to around 13.5V.
I replaced the batteries first, both the trunk (Oreilly Part # 49PRMJ) and the aux (Advanced Auto- Part No. TX14) under the hood.
Kept getting low power, no convenience functions. Took the car to have the alternator and batteries tested, found out the alternator was only putting out 65 amps. Bought a bosch alternator (Part# R111202A) at Oreillys auto parts, puts out 150 amp. I didnt know until just now reading these forums that there are two units that fit (bolt on) and I have no idea what came off the car originally or how to find out.

Writing this post, I also realized that the battery I asked for was supposed to be 900 CCA, but the battery they sold me was the 825.

I did jack up the car and the terminal post on the alternator seems nice and snug, any thoughts or pointers would be greatly appreciated!