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So my daughter calls me yesterday from a rest stop on the Delaware Turnpike. She and her husband are stuck - stopped for coffee, now the 98 VW Golf won't start. Alternates between nothing at all and dim accessories, and brighter accessories, but a clicking solenoid. Aha, say I, bad connection. I talk them through a quick cleaning of the battery terminals, still no start, same symptoms. So I grab the DMM, hop in the trusty 240, and off I go.
At rest, the battery is putting out 12.45 volts. I check several places down stream, get the same reading. Check from the ground side, same reading. All in all, ten separate tests at various locations at or beyond the battery give 12.4 - 12.5 volts, even at the starter, so I rule out cables. Still no crank.
I jump the car, and even without my car runnin, the Golf fires right up, and now the DMM is showing 14.55 volts, just like it's suppposed to.
I follow them home, car runs perfectly, no idiot lights, no dimming or brightening lights, no funky smell, all seems well. At their home, they turn off the car, try to restart, and get nothing, no crank. Still getting 12.5 volts from a half dozen positions.
So, I'm officially confused. How can a battery hold 12 volts of charge, many points downstream of the battery show 12+ volts, and still not turn the starter? Especially when a alternate 12 volt source (my car, + to battery post, - to manifold) does?
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