Li-ion polymer (LMO)
Hyundai Sonata Hybrid / Kia Optima Hybrid 1st-gen Lithium Polymer Battery (2011-2012)
The Hyundai Sonata Hybrid / Kia Optima Hybrid 1st-gen Lithium Polymer Battery (2011-2012) is the high voltage battery in the Hyundai Sonata Hybrid (2011-2012), Kia Optima Hybrid (2011-2012).
At a Glance
- Li-ion polymer (LMO) chemistry
- 270 volts nominal
- air; cabin air drawn into battery area and exhausted out the back cooled
Specifications
| Chemistry | Li-ion polymer (LMO) |
|---|---|
| Cell format | prismatic |
| Cell maker | LG Chem |
| Nominal voltage | 270 V |
| Energy | 1.4 kWh |
| Cooling | air; cabin air drawn into battery area and exhausted out the back (no liquid cooling) |
| Location | trunk, behind rear seat |
| Weight | 43.5 kg |
Cars That Use It
- Hyundai Sonata Hybrid 2011-2012 YF generation, 2.4L Theta II + 30 kW motor Run the checklist
- Kia Optima Hybrid 2011-2012 TF generation; Kia ERG (2012-2016) lists 270V DC system; shared Hybrid Blue Drive system Run the checklist
What Goes Wrong
Reported failures, each from a source listed below, as of October 7, 2026.
- Owner complaints NHTSA lists under the Hybrid Propulsion System component for the Hyundai Sonata Hybrid, Kia Optima Hybrid, by model year: 2012: 1 · 2012: 3. These are all hybrid system complaints, owner reported and unverified, not only battery faults, as of 2026-10-07.
- Hyundai TSB 23-HC-001H-1 (August 2023, 2011-2015 Sonata Hybrid) says the HEV safety plug or the power relay assembly (PRA) can set DTCs P0A0D, P1B25, P1B76 or P1B77, and tells technicians to check these parts before diagnosing the hybrid battery itself. (static.nhtsa.gov: MC-10241797-0001.pdf, 2026-10-07)
Symptoms
- Hyundai TSB 23-HC-001H-1 lists a cluster message reading 'Hybrid System Warning! Safely stop and Do Not Drive', a Check Engine light and a blinking service (wrench) indicator on 2011-2015 Sonata Hybrids with a safety plug or PRA fault. (static.nhtsa.gov: MC-10241797-0001.pdf, 2026-10-07)
- The same Hyundai bulletin describes no 'EV Ready' mode or a Ready light that blinks on and off, and a car that will not move from a stop or whose engine will not start. (static.nhtsa.gov: MC-10241797-0001.pdf, 2026-10-07)
- Kia's Optima Hybrid (2012-2016) emergency response guide says the battery is cooled by an electric fan drawing cabin air through an intake on the rear package tray, and that a blocked intake can let the hybrid battery overheat. (morongocsd.specialdistrict.org: Kia+Optima+HEV+2012-2016+ERG.pdf, 2026-10-07)
Warranty
Hyundai's 2021 Warranty Coverage Guide (dealer guide for 2011-2021 models) lists the Sonata Hybrid battery at 10 years/100,000 miles for original and later owners of 2011 models, lifetime coverage for the original owner of 2012 models (10 years/100,000 miles for later owners), and 10 years/150,000 miles for 2012 cars certified SULEV/PZEV in California-emission states; Kia Optima Hybrid coverage for 2011-2012 was not confirmed from a Kia booklet. (static.nhtsa.gov: INRD-PE21010-15928.pdf, 2026-10-07)
Get This Pack Tested
Do not open it yourself. The pack can hurt you with the car switched off.
Sources
- hyundainews.com: 21956-2011SONATAHYBRID.pdf
- gardnerweb.com: hyundais-remarkable-hybrid
- hyundainews.com: 22046-HYUNDAIADDSMOREVALUEANDCAPABILITYTO2013SONATAHYBRID,MA
- morongocsd.specialdistrict.org: Kia+Optima+HEV+2012-2016+ERG.pdf
- osti.gov: 1097169
- greencarreports.com: 1071692_hyundai-gives-2012-sonata-hybrid-battery-a-lifetime-
- hyundaiusa.com: america-best-warranty
- kia.com: warranty
- static.nhtsa.gov: INRD-PE21010-15928.pdf
- static.nhtsa.gov: MC-10241797-0001.pdf
- NHTSA complaints, 2012 Hyundai Sonata+Hybrid
- NHTSA complaints, 2012 Kia Optima+Hybrid
Last updated October 7, 2026. Failure and recall notes are as of that date. Spotted a mistake, or speaking for a maker? Report an error.
Hybrid Battery Test is independent. It is not affiliated with, sponsored by or endorsed by Hyundai, Kia, LG Chem. Names and part numbers are used only to identify the vehicle and the part.