There's two things to look for. The most common is a defective diode inside the generator. That will reduce its output capacity to exactly one third of its rated value which isn't enough to run the entire electrical system, especially at low engine speeds. A professional load-test will identify that by the lower than expected output current and "ripple" will be very high. If the generator is defective, replace the battery at the same time unless it is less than about two years old. The damage to the diodes and / or voltage regulator is caused by huge voltage spikes these generators develop, (which can also contribute to elusive engine running problems). As the battery ages, it loses its ability to dampen and absorb those spikes.
Given the additional dandy symptom you mentioned about a squeal, there may be nothing more wrong than a loose belt. If your generator has an external fan right behind the pulley, push on that with your thumb. (Please do that with the engine not running)! If you can spin the pulley at all under the belt, it's too loose. Next, tug anywhere on the belt and watch if a spring-loaded tensioner pulley moves and springs back freely. If one is used and it's not springing back freely and maintaining tension, it must be replaced.
Thursday, February 21st, 2013 AT 4:07 PM