Dead Battery?

Driving along early this morning (Sunday) in my 2000 MB ML320 with 302,000 mi on the clock. What I had thought was the alternator light had been on very dimly, and it had been my intention to take it in to the shop Mon AM. Suddenly the car lost power and was totally unresponsive to the throttle, but it kept running. As luck would have it I was passing a WalMart (This is NJ there’s a WalMart every 10 mi or so), and I managed to pull into the parking lot. The idle was very rough. I turned it off, and when I tried to turn it back on, there was a solenoid click but no crank. Dead battery I figured. As luck would have it They had a battery to fit for only $75. Using the boys’ admonition to try the cheap stuff first. I bought it and installed same within a half hour. Car started right up - no light on the dash. The light that had been on was a picture of a battery. Now here’s my question: Won’t a car run with a bad battery if the charging system’s OK? Was the light indicating a bad battery or a bad charging system? I would look this up in the woefully inadequate owner’s manual, but I got it wet a few years ago and all the pages are stuck together rendering it even less useful than it was to begin with.

You’re right to suspect the charging system, too. How old was the battery? You should get the charging system checked out on Monday.

2+ years

If the battery goes bad the charging system should keep the vehicle running if the lights, radio, wipers, heater and other voltage robbing devices are not used. When the engine idles or otherwise slows down then it may shut off regardless. The vehicle uses an onboard computer and needs a strong 12VDC to keep it running. I thinks it’s very wise to have the charging system checked out as soon as you can. You don’t want the new battery to discharge.

Thanks. My thought too.