mitsubishi mighty max altinator not charging battery

i have a problem with my truck. the altinator does not charge the battery and the altinator has been replaced and you can disconnect the battery and the truck will still run but it will not charge the battery. the altinator has been tested and there is nothing wrong with it. is there anyone else who has had this problem and that would possibly know what is wrong with it. Thanks

clean the battery cables (ground) both ends

i have a 91 mighty max and im having the same problem. i have replaced the altinator and i have bought a new battery. my battery will not charge when i turn my headlights on. in the daytime its fine. and it runs perfect, but when i put my lights on it kills the battery and the lights dim and the radio cuts in and out. if anyone has any suggestions about what can be doing this id appreciate it. its getting old fast :banghead:

check the fuses at the pos batt post