2001 Windstar battery light!

I have a brand new alternator. I have just tested my battery found out it has good voltage. Connections are all good and clean as far as I can tell.
Van runs lower idle and air conditioning blows slow when is is on high
and battery light stays on permanetly. Eventually, all the lights in the dash come on the gauges go up and down (speed) then it will just die. What is happening here? Is there something else I should check? Thanks, Larry

Check the 15amp fuse #20 in the box next to the battery.

Do you have a voltmeter?

Check the 15amp fuse #20 in the box next to the battery.

Do you have a voltmeter?
Is that in the power distribution box? No I sure don't have a voltmeter. i will go and check it out. thanks

Yeah, the "battery junction box" (per the diagrams). You have a relay and fuse layout in the glove box manual.

If you can get your hands on a voltmeter ( I prefer the old style analogue type for most auto work), you should read voltages around the battery, the altenator, and on top of all the fuses in the battery junction box (with key "on"... engine not running) to see if anything is abnormally low.

Yeah, the "battery junction box" (per the diagrams). You have a relay and fuse layout in the glove box manual.

If you can get your hands on a voltmeter ( I prefer the old style analogue type for most auto work), you should read voltages around the battery, the altenator, and on top of all the fuses in the battery junction box (with key "on"... engine not running) to see if anything is abnormally low.
I checked all the 15 amp fuses and they all look good

I checked all the 15 amp fuses and they all look good
The battery checked out good but when it runs the battery just dies out I'm assuming the vehicle will just konk out

I recommend a trip to Radio Shack.