12V 45Ah Lead-Acid Auxiliary Battery for Model 3 and Model Y
This 12V 45Ah lead-acid battery replaces the auxiliary battery on compatible early Model 3 and Model Y vehicles. It serves the low-voltage electrical system and installs in the front trunk battery position. It replaces original battery reference 1129182-00-B.
- 12V
- 45Ah
- Lead-acid
- Reference 1129182-00-B
Key Features
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12V Lead-Acid Design
A replacement auxiliary battery for vehicles originally equipped with the matching 12V lead-acid system.
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45Ah Capacity
The specified capacity is 45Ah.
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Reference Number
Replaces original battery reference 1129182-00-B.
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Low-Voltage Supply
Serves the vehicle low-voltage electrical system, including control modules, locks and lighting.
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Original Battery Position
Installed in the front trunk battery location using the correct vehicle procedure and retaining hardware.
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Lead-Acid Vehicles Only
Fits vehicles with a factory lead-acid low-voltage battery. Does not fit lithium-ion low-voltage systems.
Highlights
Low-Voltage Battery Replacement
A single lead-acid auxiliary battery for the matching factory system. The battery supplies low-voltage vehicle equipment; replacing it does not increase high-voltage traction battery capacity or driving range.
Original Battery Position
Replaces the original 1129182-00-B battery in the front trunk battery position.
Battery Type
Open Controls > Software > Additional Vehicle Information to see the low-voltage battery type. This battery replaces lead-acid batteries only.
Installation for the Exact Vehicle
Battery access and power-isolation procedures vary with vehicle equipment and production version.
Compatibility
| Model | Years / Version | Notes |
|---|---|---|
| Model 3 | 2017–2021 | Factory lead-acid version only; replaces reference 1129182-00-B. |
| Model Y | 2020–2021 | Factory lead-acid version only; replaces reference 1129182-00-B. |
Production transitions vary by factory. Fits factory lead-acid versions only. Excludes lithium-ion low-voltage systems, Model 3 Highland, Model Y Juniper, Model S and Model X.
Specifications
| Product Type | Low-voltage auxiliary battery |
|---|---|
| Compatible Models | Model 3 2017–2021 and Model Y 2020–2021, factory lead-acid versions only |
| Position / Location | Front trunk battery position |
| Capacity | 45Ah |
| Voltage | 12V |
| Package Contents | 1 × low-voltage battery |
| Battery Chemistry | Lead-acid |
| Reference Part Number | 1129182-00-B |
What's in the Box
- 1×12V low-voltage battery
Installation
- Prepare access and isolate vehicle power using the procedure for the exact vehicle configuration; use appropriate protective equipment and prevent terminal short circuits.
- Remove and replace the battery following that procedure, retaining the correct hold-down and restoring the required vent hose and plug arrangement.
- Restore vehicle power and panels as specified.
Good to Know
Caution
- Use only on a matching factory lead-acid low-voltage system; do not substitute it for a lithium-ion battery.
- Keep the battery upright, protect its terminals and recycle the old battery through an appropriate collection facility.
Care
- Keep the battery upright when handling or transporting it, and protect its terminals from contact with tools or metal objects.
- Follow battery handling instructions and local recycling requirements; use a battery collection facility for the old battery.
- A low-voltage warning can have several causes. Diagnose the vehicle before assuming a replacement battery will resolve every wake-up, locking or charging problem.
FAQ
Will it fit every 2021 Model 3 or Model Y?
No. It fits 2021 vehicles with a factory lead-acid low-voltage battery only. Vehicles with lithium-ion low-voltage batteries require a different replacement.
Is this a lithium-ion conversion?
This is a 12V lead-acid replacement for a matching factory lead-acid system. It is not a conversion kit for another low-voltage architecture.
What if the vehicle has no low-voltage power?
Hood-release power connections are not battery-charging connections.
Will this increase driving range?
It replaces the low-voltage auxiliary battery. It does not add capacity to the high-voltage traction battery.
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