EV Battery State of Health (SOH)
What Is Battery State of Health (SOH) in an Electric Vehicle?
As electric vehicles (EVs) become more common, understanding how their batteries age is increasingly important, especially if you’re buying a used EV or want to keep your current one running efficiently. One key metric that helps assess battery condition is State of Health, or SOH.
What Does SOH Actually Mean?
Battery SOH is a measure of how well an EV battery performs compared to when it was brand new. It’s usually expressed as a percentage:
- 100% SOH means the battery is performing at full original capacity.
- 80% SOH means the battery can only hold 80% of the energy it could when new.
SOH gives you a snapshot of the battery’s remaining usable life, helping you understand whether it’s still fit for purpose or starting to degrade.
Why Does SOH Matter?
SOH affects:
- Driving range: Lower SOH means fewer miles per charge.
- Charging behaviour: Degraded batteries may charge more slowly or unevenly.
- Resale value: Buyers want to know the battery is healthy.
- Repair decisions: At LKQ Electriq, we use SOH to help decide whether a battery needs repair, reconditioning, or replacement of specific modules.
How Is SOH Measured?
There’s no single method, it depends on the vehicle and the tools available. Common approaches include:
- Onboard diagnostics: Some EVs display SOH in the vehicle’s software.
- Specialist tools: We use advanced diagnostic equipment to read battery data directly.
- Voltage and resistance testing: These help us assess individual modules inside the battery pack.
At LKQ Electriq, we go beyond surface-level readings. Our technicians look at real-world performance, thermal behaviour, and charging patterns to build a full picture of battery health.
Below is an example of a chart for testing a lithium cell capacity
Can SOH Be Improved?
Not directly — SOH reflects physical wear. But:
- Repairing faulty modules can restore performance.
- Balancing cells can improve efficiency.
- Software updates may help recalibrate readings.
We specialise in repair-first solutions, meaning we aim to fix what’s wrong rather than replace the whole battery.
SOH is a vital part of understanding your EV’s battery health. Whether you’re buying, selling, or maintaining an electric vehicle, knowing the SOH helps you make informed decisions.
If you’re unsure about your EV’s battery condition, we’re here to help. Our team at LKQ Electriq can assess your battery, explain what the numbers mean, and offer expert repair options tailored to your vehicle.
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