Nissan hardbody wont charge

[borrowedeye]

I have a 1995 nissan hardbody that wont charge. the alternator and battery are brand new.
I replaced the alternator because the truck dies just like the alteranter is bad, the lights fade and the truck sputters, I took it to a mechanic for a cheap fix, he ran a hot wire from the battery to the alternator and that solved the problem for about a month and then all over again it started happening. I will charge the battery after which I can drive for about 3-4 hours depending on if I use lights or not. It is driving me nuts, I dont have money to have nissan throw parts at it and I dont know much about electrical. So if you all have tips or have had this problem let me know.
Thanks for the help.

 

[Devils Paw 80]

Isn't there any place in your area that can check out your charging system for free? It's possible that your alternator is bad again. Have someone else check out the charging system for you. It doesn't have to be the dealer, or Nissan parts, that you use.

 

[borrowedeye]

last ti9me i had the alternator out i took it to three differant place to have it check. and i put the tester on the battery as it was running and it said 13.5 so i am super confused.