Anyone have an overcharging alternator fry a battery?

Johnny Mac said
About the same time engine starts coming to temp, so I flick the fan on. Seemed to come to temp faster than normal, but it was 85 degrees. On e85, I rarely even use the fan, so thought that was weird

If the charging system was faulty (for what ever reason) you might not have had electric fans when you turned the switch.

Johnny Mac said
and the sun is blaring, but it looked like 17+. (Digital and hard to see in direct sun)

17 v will boil the water out of the battery. And is hard on other 12v electrical components.

Johnny Mac said
Pull alt belt, no noise.

Narrows it down to alternator

Johnny Mac said
I can hand spin it and reproduce noise.

Confirms there is a problem in the alternator.
I would disassemble the alt a d see if there is anything obviously wrong

Johnny Mac said
Anyways, title question....think my 17v overcharge for 5 miles killed my battery

May have boiled the water out so check that in the battery. Then put battery on a trickle charger. I would pull the battery out of the car and do the charging away from anything that could get damaged if the battery explodes.

Johnny Mac said
With a completely fried battery, would the overcharging alt mess with my elec water pump and fans and cause it to run hotter

As noted before a shorted battery will make the alt try to charge at max charge. BUT I am not sure if it would go to 17v

In my experience a really bad battery will keep the voltage lower not higher.

The VR in the alt ( somewhere it was stated tyou have a 1 wire alt) should regulate the voltage to keep things safe. So I'm not sure the alt fried the bat or the bat fried the alt.

But based on what you have said I'm leaning on alt had a problem and over charged the battery causing the cells to go dry.