Navigating electric vehicle (EV) battery health checks at dealerships can sometimes be challenging. It’s been noted that some dealerships may rely solely on their proprietary diagnostic tools, like the KIA Diagnostic Unit (KDU), potentially overlooking or dismissing battery health indicators not directly registered by their system. There are reports suggesting that certain dealers might apply Battery Management System (BMS) updates as a perceived quick fix to improve the displayed range on meter (GoM). However, applying these updates before properly assessing the battery’s State of Health (SOH) can lead to inaccurate readings. This is because BMS updates can reset to default values, requiring several charge cycles to gather reliable data. Consequently, owners might receive a superficially high SOH reading post-update, often exceeding 70%, which may not reflect the actual battery condition.
To ensure a thorough and accurate battery health assessment, especially if you suspect battery degradation, it’s advisable to be proactive. Come prepared with a copy of Kia Technical Service Bulletin (TSB) PS548. Request that the dealership strictly adhere to the procedure outlined in PS548, emphasizing your understanding that BMS updates should not be performed prior to obtaining a baseline SOH reading. Highlight the relevant sections in the PS548 document to draw their attention to the critical steps for accurate diagnosis.
If the SOH reading, obtained following the correct PS548 procedure, is below 70%, this should necessitate the dealership to report the findings to KIA Corporate, potentially leading to a battery replacement under warranty.
Beyond relying solely on dealership diagnostics, EV owners can also independently estimate their battery SOH using a practical calculation method. This method provides a supplementary check and can be performed using data readily available from your vehicle’s dashboard.
Here’s how to calculate your EV battery State of Health (SOH):
- Charge and Reset: Begin by fully charging your EV battery. After charging is complete, reset your vehicle’s energy consumption meter (m/kWh). This meter should display “–” upon reset. Note the odometer reading and the battery percentage displayed (if it’s not already at 100%).
- Drive and Discharge: Drive your vehicle until you need to recharge. Note the new odometer reading and the battery percentage just before you commence charging. Also, record the m/kWh value displayed.
- Calculate kWh Consumed: Determine the difference in mileage from step 1 and step 2. Divide this mileage difference by the m/kWh value you recorded. This calculation yields the kilowatt-hours (kWh) of energy consumed during your drive.
- Calculate 100% Capacity: Calculate the percentage difference in battery levels from step 1 and step 2. Convert this percentage difference into a decimal fraction (e.g., a 10% difference is 0.10). Divide the kWh consumed (from step 3) by this decimal fraction. This result approximates your battery’s current usable capacity at a 100% charge level.
- Determine SOH Percentage: Identify the nominal battery capacity of your EV model (e.g., 27 kWh, 30 kWh, 39.2 kWh, 64 kWh, or other specified value). Divide the calculated 100% capacity (from step 4) by this nominal battery size. Multiply the result by 100 to express the State of Health as a percentage.
This DIY SOH calculation method has been tested and shown to closely align with readings obtained from specialized EV diagnostic tools, offering a reliable way for EV owners to monitor their battery health. While an Electric Car Scanner provides in-depth diagnostics, this calculation serves as a valuable, accessible method for owners to stay informed about their EV battery condition and engage more effectively with dealerships regarding battery health concerns.
