94 Aspire charging problem

Just happened to be at Auto parts store when car wouldnt crank. Had them check it an said my Alternator was bad. Replaced Alternator and still wouldnt charge. Got another under warranty and they checked 1st alt and said it was good. Same problem again. and that Alternator checked good. but I'm tired of standing on the side of the road because neither Alternator charges my battery?? Anyone had this problem?? This aint my first rodeo. Been working on my own auto's for 30 years but this has me stumped!

 

First of all, an alternator doesn't start the vehicle, it charges the battery and runs the electrical system when the engine is running. First, you have to check why the engine wont turn over or the starter won't crank. This includes the battery and starter and wires, relays, connections, etc. Then if you find out the battery is dead, then suspect an alternator but still a new alternator is not going to start an engine if the battery is dead because the starter needs voltgage from the battery not the alternator. Once the engine starts then the alternator takes over and runs the electrical system and also recharges the battery. Sometimes a battery won't except a charge. Give the battery and real good look at. Check the voltage, clean and inspect the terminals and the water level and even each cell, with a hydrometer or a 12 volt test light. If the battery checks ok, than move onto checking the starter and any connections and cables including the ground and relays. If you have at least 9.6 volts at the battery then your starter should ingage. You cant really test anything untill you have 12 volts at battery, that includes testing the alternator.

 

You have a breakdown somewhere between the alternator and the battery or the battery is toast. After you check the battery it's time to get out the multi-meter and start tracing wires.

As Homeowner says, can't properly check the system without a fully charged battery. I would be interested how the parts guys diagnosed alternator without the engine running and whether they did a proper test on the battery.

 

Under the intake manifold, in the 10ga wire from the alt to the battery ia what is probably a failed fusible link