The findings suggested that PHEV battery performance may be more heavily influenced by differences in charging behaviour, usage profiles and driving patterns.
Plug-in hybrid vehicles (PHEVs) show greater variation in battery health than battery-electric vehicles (BEVs) in the used market, according to analysis from Generational.
The electric vehicle (EV) battery diagnostics business analysed 2,000 used plug-in vehicles from automotive retailers across the UK, covering 1,000 plug-in hybrid electric vehicles (PHEVs) and 1,000 battery-electric vehicles (BEVs) of comparable age and mileage.
The research found that both groups retained strong average battery State of Health (SoH), with PHEVs averaging 94.27% and BEVs averaging 94.94%.
However, the data showed wider variation among PHEVs, which recorded a 5.48% SoH standard deviation compared with 4.14% for BEVs.
Generational also found that 4.70% of PHEVs had an SoH below 85%, compared with 1.50% of BEVs.
The findings suggested that PHEV battery performance may be more heavily influenced by differences in charging behaviour, usage profiles and driving patterns.
BEVs were found to be typically used with more consistent charging routines, because the battery acts as the vehicle’s primary energy source, while PHEVs may be driven in a wider range of ways, including more limited battery usage or more frequent shallow charging cycles.
Oliver Phillpott, chief executive of Generational, said: “Average state of health evidently remains strong across both PHEVs and BEVs.
“What stands out is the wider spread of results among PHEVs, which underscores how both buyer and seller need to double down on checking the usage profile of the vehicle in question.
“Even while the averages are reassuring, for both parties the data reinforces how battery condition is something that needs to be assessed on a case-by-case basis.
“Transparent testing allows strong vehicles to be priced confidently and problematic vehicles to be identified early.
“So, across both segments, retailers and consumers can go into the market confident of finding a robust vehicle to meet their needs.”
The analysis follows publication of Generational’s 2025 Battery Performance Index, which was based on more than 8,000 battery health assessments conducted across the UK used EV market.
That report found average battery health of 95.15% across tested vehicles and concluded that battery degradation was not the systemic risk it is often assumed to be, although variation between individual vehicles becomes more important as vehicles age.
Phillpott added: “The used EV and PHEV market is entering a rapid growth phase. Buyers increasingly understand that the battery is the most valuable component in the vehicle, but they still need clear, trusted information before they can buy with confidence.
“Our latest analysis shows why a single mileage or age figure cannot tell the whole story. Battery condition is becoming the defining factor in used plug-in vehicle value, and the industry now has the data and tools to make that condition visible.”