Knowing the State of Health (SOH) of your Kia’s battery is crucial for understanding its performance and longevity. While dealership diagnostic tools can provide this information, discrepancies can arise. This guide explains how to ensure an accurate SOH reading using a car scanner and manual calculations, empowering you to make informed decisions about your electric vehicle’s battery.
Dealerships often rely on the KIA Diagnostic Unit (KDU) to assess battery health. However, applying BMS updates before taking a reading can skew the results, often displaying an inflated SOH well over 70%. To obtain a reliable reading, referencing Kia Technical Service Bulletin (TSB) PS548 is crucial. This document outlines the correct procedure for obtaining the SOH, emphasizing the importance of reading the BMS data before applying any updates. Requesting the dealer to adhere strictly to PS548, highlighting the specific instructions regarding pre-update data reading, can ensure an accurate SOH assessment. A reading below 70% often triggers a report to Kia Corporate, potentially leading to a battery replacement.
Beyond relying on the dealership, you can calculate the SOH yourself using a car scanner capable of displaying energy consumption in mi/kWh (or km/kWh). After fully charging your vehicle, reset the mi/kWh reading. Note your current mileage and battery percentage (if not 100%). At your next charge, record the mileage and battery percentage before plugging in and note the mi/kWh reading.
To calculate the SOH, follow these steps:
- Calculate kWh consumed: Subtract the initial mileage from the final mileage and divide the result by the recorded mi/kWh.
- Determine usable battery capacity: Subtract the initial battery percentage from the final battery percentage (e.g., 90% – 20% = 70%). Convert this difference to a decimal (70% = 0.7). Divide the kWh consumed (from step 1) by this decimal.
- Calculate SOH: Divide the usable battery capacity (from step 2) by your vehicle’s nominal battery capacity (e.g., 27, 30, 39.2, or 64 kWh, depending on your model). Multiply the result by 100 to express the SOH as a percentage.
This manual calculation method has been verified against professional-grade diagnostic tools, demonstrating its accuracy in determining SOH. By understanding these procedures, you can confidently assess your Kia’s battery health and advocate for necessary maintenance or replacement.
