1990 Lebaron charging problems
 

My brother in law was over the other day talking to me about doing the oil change and tranny filter and fluid change. I found a some battery acid on his terminals, so I did old trick my one mechanic taught me take a little bit of tranny fluid and put on the terminals to eat the battery acid. All I got on the terminals was like a drop or two nothing major. When he left the charging gauge dropped down to around 10 or so. He didn't bother to let me know about it until Tuesday when he started to lose all his dash lights and the gauge dropped down to 8. I cleaned his terminals and check the acid level in the battery. They were down some so I filled the up with water and it never improved for him. When he took it autozone they said his alt was dead and gave me a price of $200 for a new one. Tuesday night if he was lucky he could drive maybe a mile or so before she would die at the red light and then I would have to jump it again in the street, when I followed him home.
Yesterday his belt seemed loose ( I could turn it one complete turn.) I got him a belt tensioner from the local you pull and now the belt is still doing the same thing. The tensioner is pretty tight because I give it a good push to get the belt back on. From what I understand the belt is about 2 years old. His brother the previous owner didn't drive it that much (pretty much just back and forth from H. S.) When I give the belt a tug before and after installing the "new" tensioner the Power steering pulley makes a noise and you can see move a little. Is this normal? After I installed the tensioner and gave it a jump with my jeep the charge level went from like 10 up to 13 then just dropped back down to 8. I killed it because it was acting like it was going to die and the dash lights went out. Every time I jumped it Tuesday night his dash lights would go out as soon as I pulled the jumper cables off my battery. I am giving the battery a full charge this morning. The car ran for about a hour and the charge level went back down to 8 again.
I got 5 check engines codes when I did the key on key off sequence. They are 12, 41,25,47,55. This was the order of them. After I pulled the battery cable for 30 seconds and gave it another jump which the level when from 10 back down to 8 again. After it ran for about 5 minutes of me revving it to try to keep it going I got the codes 12,41,25,55. The same order again.
Can someone please give me some help. My sister and her husband have to keep bumping rides from co workers and me until I can get it fixed for them.
Thanks for all the help in advance,
DR