Okay, I messed up

I went to jump my John Deere 2030 diesel (24 volt system)
Battery charger on one battery
2002 Caravan on the second battery

I have done this before with other vehicles, multiple times with no problems...

Did not want to start so I decide it to let it charge for a while, 10 minutes
Walk outside van is dead no lights, wont start wont charge

What did I fry?

Thanks

 

I would make sure you have battery voltage and start checking the PDC. Does it smell fried?

 

Checked Voltage, seems to be reversed polarity?

11.3 volts

 

New battery
Cranked right over...

Yes the battery had reversed polarity

 

Seen batteries do that for no reason, Happen to our pontoon boat.

 

Welp I never stop learning.