When purchasing a diesel generator set, most people focus only on the engine brand. However, the alternator (generator end) is just as important — it directly determines the output performance, stability, and service life of the entire generator set. Full copper alternators and aluminum-wound alternators can differ in price by 30%–50%, but their quality gap is even greater. To help you avoid costly mistakes, here are three key techniques to quickly identify alternator quality. 1. Check the Material: Copper Wire vs. Aluminum Wire The material used in the stator windings is one of the most important indicators of alternator quality. Advantages of Full Copper Alternators Excellent electrical conductivity Lower heat generation Not easily oxidized Longer service life (typically 15–20 years) Higher efficiency and stronger load capability   Disadvantages of Aluminum Alternators Higher electrical resistance Poorer conductivity More prone to oxidation and breakage Higher ...