You have already put a load on the battery by testing the starter directly on the battery. When a load is applied to the battery and the voltage drops down to 8.5 VOLTS - It's the BATTERY. It either needs charging or replacement.

You really need to explain in a detailed correct fashion and use the right terms to help people assist you. ie: 85!!!! Even 8.5 doesn't give the full information.

 

It is a brand new battery and is fully charged to 12.6., it dropped down to 8.5 when it was connected to the starter and went back to 12.6 when it was disconnected from the starter.

 

Charge the battery, and take it to the nearest auto parts store for a free battery load test and report the numbers here. It does sound like a bad battery.

But when you removed the battery while it was running, who knows what damage that may have done. Damage to the alternator. The positive cable may have touched ground while you were messing with it. Then driving it with the severely discharged(or possibly even bad) battery was also a bad idea, may have damaged the alternator.

You say it won't crank, but then you say it just makes a spinning sound when you try to crank.

 

Nope, you are right . Being that the battery is new eliminates the battery as being at fault. So don't bother to test it even though several have suggested you do that.

I'm out.

 

When you say connected to the battery.
Are you saying all you did was install the large cable to the starter ?
Or did you turn the ignition key to start and spin the starter ?
Voltage drop is below spec for the starter motor vs battery.

 

I'll guess this wasn't a real test but you just seeing if it would spin when off the car.
I recently rebuilt a riding lawn mower starter and bench tried it. Worked fine. Put it on the mower and would barely turn over with a fully charged battery.
Point being. The correct way to test a starter off the vehicle is to do a load test on it.
Back in my mechanic days, I had a local starter/alternator shop supply all my replacements. The old man/owner really knew his stuff. I watched him several times bench test a starter by pushing a 2x4 against the gear as it was spinning. His way of testing the power of the starter motor. Guess he knew just how hard to push against it to check.

 

I’ve found over the years, bench tests are great, but 9 X outta 10, you need a new starter, or whatever you are testing!

 

Took the starter to AutoZone and had it tested and they said it was fine. so back to square one.