What Are the Causes of Insufficient Power Generation in Automotive Generators?

[DeBrynlee]

"Excessively high or low no-load voltage can lead to insufficient power generation in automotive generators. Excessively high no-load voltage: Automatic voltage regulator failure. Excessive current in the no-load exciter field winding. Inspect the automatic voltage regulator; if the set voltage is too high, readjust it. Excessively low no-load voltage: Open circuit in the exciter field winding. Check if the exciter field winding resistance is infinite. Replace the broken winding or reconnect the circuit; severe short circuit in the main generator field winding. High current in the exciter field winding. The main generator field winding overheats significantly, vibration increases, and the DC resistance of the field winding is much lower than normal."

[HeidiFitz]

I previously encountered the issue of insufficient generator output while driving, and there are several common causes. The most frequent one is a loose or damaged belt. If the belt is loose, the generator doesn't spin fast enough, naturally leading to insufficient power generation. My car had this problem due to an aged belt, causing the battery to never charge fully. Next is the wear of carbon brushes or issues with the slip rings. Over time, brushes can carbonize and lead to poor contact, affecting current transmission. A faulty voltage regulator can also cause unstable output voltage—too high or too low is problematic. Corrosion or loose connections in the wiring can interrupt power generation as well; in my case, the connector was severely rusted. If these issues aren’t addressed promptly, the battery can drain, lights may dim, or the car might even fail to start. I spent quite a bit on repairs and regretted not checking the belt tension earlier.

[LeElizabeth]

I've been troubled by the issue of the alternator not generating enough power, mainly due to problems with the belt, such as being too loose or broken, which prevents the alternator from spinning fast enough to produce sufficient electricity. Worn-out brushes can also affect performance, as accumulated carbon dust leads to poor conductivity. If the voltage regulator fails, it can't control the voltage properly, resulting in either insufficient or fluctuating power output. Additionally, corroded or loose wiring connections can obstruct current flow. This can lead to an undercharged battery, and suddenly stalling during a long drive is quite frightening—I almost had an accident myself. Now, I regularly check the belt and the battery charging light to prevent such issues.

[Dallas]

There are quite a few reasons for insufficient power generation in a car alternator. A loose or severely worn belt can cause insufficient alternator speed. Worn-out brushes inside or rusted slip rings lead to poor contact. If the voltage regulator is faulty, the output voltage will be too low. Corroded or disconnected wiring connections can also be the culprit. All these issues result in insufficient battery charging, causing lights to dim while driving. It's better to get it fixed promptly.