Lexus CT200h Battery: Specs, Fitment & Common Faults

A genuinely important safety point: because this is a hybrid, the 12V battery genuinely cannot be jump-started conventionally — it needs trickle charging, or the hybrid system's circuits risk damage, especially after a couple of weeks standing unused.

Illustration for editorial purposes

OEM Part Number: 28800-AZC34

Genuinely important to know: the CT200h's 12V battery is a small auxiliary unit, genuinely separate from the hybrid drive battery (a completely different, much larger component). A CT200h Forums member directly reported their genuine Toyota-supplied SB46B42R replacement was slightly bulkier than the original and sat at a slight angle when held down, but fitted without losing any presets.

2012-2020, 12V auxiliary battery, genuine reference (shared with Prius, Prius+, Auris)	Lexus OEM: 28800-AZC34 (also referenced as 28800-YZZPD) — S46B24R, 35-45Ah
Alternative genuine reference	Lexus OEM: 2880021171 (also 28800-21171, 2880021170)
Important	Never confuse this with the hybrid drive battery — genuine part G951076012 — which is a completely different, much more expensive component.

The Part Everyone Blames First, Not Always Correctly

A car that won't start gets blamed on the battery more often than any other component, and it's right often enough to make that assumption a reasonable first check. But it's not always the actual cause, which is worth knowing before spending money on a replacement that doesn't fix anything.

Before you buy: battery size, capacity and type (standard vs AGM/EFB for stop-start systems) vary by trim and engine. Always confirm against your VIN before ordering.

What It Does

The 12V battery provides the power needed to start the engine and runs electrical systems when the engine isn't turning. On cars with stop-start technology, the battery works much harder than on older designs, since the engine switches off and restarts far more frequently — which is exactly why these cars need a specific AGM or EFB battery type rather than a standard unit.

A Genuinely Important Safety Point Worth Knowing About This Hybrid — Lexus CT200h Battery

This is genuinely important to understand before attempting to jump-start a flat battery: because this is a hybrid, the small 12V auxiliary battery genuinely cannot be jump-started in the conventional way. Instead, it needs to be trickle charged specifically, since attempting a standard jump-start risks genuine damage to the hybrid system's circuits — worth keeping this in mind given how easily a hybrid battery can go flat after a couple of weeks of standing unused.

A genuinely useful, real UK cost figure worth knowing: the average price for a 12V battery replacement on related Lexus hybrid models has been documented at around £247.

It's also genuinely worth knowing a specific diagnostic finding if you're chasing a persistent parasitic drain: documented cases describe successfully isolating a drain to specific fuses, eventually traced to a specific multiplex network communication unit — worth having a proper fuse-by-fuse test carried out rather than assuming a battery replacement alone will resolve a recurring drain.

Warning Signs, DIY Difficulty & Aftermarket Advice

These are the same regardless of make or model — see our full Battery Guide for warning signs to watch for, confirming fitment against your VIN, and matching the right technology (standard, EFB, AGM) when buying aftermarket.

More Lexus Battery

The same part, covered across other Lexus models.

Lexus CT200h Battery: Specs, Fitment & Common Faults

OEM Part Number: 28800-AZC34

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A Genuinely Important Safety Point Worth Knowing About This Hybrid — Lexus CT200h Battery