Not charging with headlights on

Your photo triggered a thought. If you replace the alternator, the later design known as a square back is far superior to the older known as a round back. DO NOT under any circumstances allow a parts store to sell you a "round back"

Newer square back on left



The second reason not to accept a roundback is that many rebuilders actually converted the older 69/ earlier grounded brush design to a "newer" isolate brush by hacking the housing and adding a second isolated brush. Do NOT accept one. Below, the "hacked" brush was added at top, at 12 o clock. This one is missing, you can see the hole