This study investigates the performance of cost-effective high-voltage probes designed for electric vehicle projects (EV), with a particular emphasis on signal integrity across various frequencies and duty cycles. The paper addresses the challenges of measuring high-frequency signals in EV systems, where accuracy is essential but typically limited by the expensive cost of precise equipment. Significant errors were discovered at higher frequencies and duty cycles, which impacted measurement reliability. Both the dual opto-isolated probe, and inductive coupling probe shown a stable performance at lower frequencies, but their accuracy has decreased under more demanding conditions. These probes were deliberately intended to be cost-effective, acknowledging that high-voltage testing benches from the High Voltage Testing Laboratory cannot always be completely equipped for every project due to substantial investments and the high costs of precision instruments. The findings highlight the importance of optimizing affordable probe designs for high-voltage EV applications to ensure precise and reliable signal measurements while managing budget constraints.