I just got a new battery and got the altenator checked. They said it was fine but was putting out low amps. I start driving and the battery light comes on. And it starts to die. But once it gets really low the light will go off and it will start charging again. But this time the light came on and stayed on and my truck died. I have a 1996 ford ranger 2.3 4 cylender. What's wrong?

Perform the simple Regulated Battery Voltage Test, Item 9, in the link below:

http://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-10.html#post1973613

If it is not between 14 and 15 volts, replace or rebuild the alternator. My bet is that the alternator is bad (regulator/brush holder assembly needs replacing). Here's how to easily rebuild it yourself, and save a lot of money:

http://www.askmehelpdesk.com/cars-trucks/faq-how-troubleshoot-repair-maintain-hondas-selected-other-vehicles-46563-13.html#post2518522

If the bearings are fine, it would take just several minutes to replace the regulator/brush holder assembly.

thank you but which one do i look at in the link?

Item 9.

Start your engine and connect the black lead of your multimeter to the negative battery terminal. Attach the red test lead to the positive battery terminal. If the alternator is good, it should read 14 to 15 volts.

ok thank you.