I have been getting a low voltage reading on my dash gauge.

I stopped in Advanced to get a couple things and just had them check my battery. Battery was good but they said the battery was charging at a low voltage. Pulled the alternator and had them bench tested. Tested OK but the guy gave me a replacement anyway. Put the new alternator in and the gauge on the dash is still showing low voltage. I no not to 100% trust the dash gauge but it just started happening. Any ideas of what to check if the battery is still charging at a low voltage?

Thanks
Evan

 

They aren't mechanics, they sell parts. Most of those guys can barely work the register let alone any type of diagnostics machine. Check the voltages yourself.

 

My alternator puts out 14.6 vdc, yet the gauge indicates low. Put a voltmeter on your positive battery post and a good ground and see for yourself the actual output.

 

Since you didn't include the year, engine or any other info that might be helpful, I will assume the battery cables are original and they are at least 17 years old. If this is so, start by replacing the battery negative cable and checking the other grounding straps to the engine and transmission for good electrical connections using an ohm meter. Press one probe to the head, block, or transmission case and the other probe to the cable end that is connected nearest the frame or body.
In many cases, heat from the engine will in effect crystallize the copper strands in the battery ground (negative) cable within the last few inches of the cable that is connected to the engine block. The alternator is just one component in this electrical circuit, and high resistance at any point in any electrical circuit will effect the performance of the other components in the electrical circuit where high resistance is indicated.