NiMH

Toyota Sienna Hybrid 2021+ (AXLH40) Hybrid Battery

The Toyota Sienna Hybrid 2021+ (AXLH40) Hybrid Battery is the high voltage battery in the Toyota Sienna (2021-2026).

At a Glance

NiMH chemistry
288 volts nominal
40 modules
air-cooled; LH and RH battery cooling blower assemblies with ducts cooled

Specifications

Chemistry	NiMH
Cell format	prismatic
Nominal voltage	288 V
Modules	40
Module voltage	7.2 V
Energy	1.9 kWh
Cooling	air-cooled; LH and RH battery cooling blower assemblies with ducts
Location	cabin area under the front seats

Cars That Use It

Toyota Sienna 2021-2026 AXLH40 FWD / AXLH45 AWD; hybrid-only from 2021 Run the checklist

What Goes Wrong

Reported failures, each from a source listed below, as of October 7, 2026.

Symptoms

Toyota's 2021 Sienna Warranty & Maintenance Guide schedules an inspection of the HV battery cooling intake filter, with a visual check for dirt or dust every 5,000 miles and cleaning if necessary. (techinfo.toyota.com: T-MMS-21SiennaHV.pdf, 2026-10-07)

Same Electrical Spec

These packs share this one's chemistry, voltage and module count. That is a spec match only. It does not mean the parts fit each other, so check with a technician.

Warranty

Toyota's 2021-2026 Sienna Warranty & Maintenance Guides list a Hybrid Battery Warranty of 10 years or 150,000 miles from the in-service date, whichever comes first. (techinfo.toyota.com: T-MMS-21SiennaHV.pdf, 2026-10-07)

How battery warranties work.

Get This Pack Tested

Do not open it yourself. The pack can hurt you with the car switched off.

Book a battery test Find a tech near you

How to test a hybrid battery safely

Sources

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 Toyota. Names and part numbers are used only to identify the vehicle and the part.