Last night my car wouldn't start. It was cranking way too slow, like the battery was low. I tried using jumper cables with my other car, and it still had slow cranking. So I called AAA, and they came out with their jumper cables, and to my surprise, the cranking was still slow. I would have thought it would have picked up 12 volts from his cables. I ended up having it towed to my house.

So tonight I put my multimeter on it. The battery reads at 12V, and it does at the starter as well. So I had the wife turn the key. It drops down to 9V.

So the question is, does that sound like a bad battery? Or is a drop like that normal?

A reading of 9 volts or above with the starter turning at normal speed is normal, but a reading of 9V or more with the starter turning slow and the starter is probably bad. If the reading is less then 9V with the starter turning slow, then there is a bad connection, the solenoid contacts are burned, or the starter is bad.

I'd clean all of the cable terminals to the starter and the battery terminals first, just on principal, and try again.

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'81 D150 with "Lean Burn"

Don't forget to clean up your ground on the block as well as your battery to body ground.

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A fully-charged "12 volt" battery should read 12.6 volts. If it actually reads any much less than that, either the battery is not fully charged (something the matter with your charging system or you left the lights or something on) or there's something the matter with the battery (dead cell, internal short). Slow cranking can also be due to faulty battery cables or a faulty starter.

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Too many people who were born on third base actually believe they've hit a triple.

A weak battery could certainly cause your problem, but starters can partially short out inside too; I've seen them draw 2X the normal current and sort of work (and smoke).