What is the battery capacity of the Lexus RX400h?

The Lexus RX400h uses a nickel-metal hydride (NiMH) battery pack with roughly 1.3 kilowatt-hours (kWh) of capacity.

The RX400h, launched in the mid-2000s, combines a gasoline engine with an electric motor powered by a high‑voltage NiMH battery. The energy capacity of this pack is a key figure because it determines how much electric‑only assist the hybrid can provide and how far it can travel on electricity alone under certain driving conditions. While the system can operate with electric propulsion, most power comes from the gasoline engine, especially at higher speeds or during aggressive acceleration.

Battery specifications

Below are the commonly cited numbers that describe the RX400h's high-voltage battery system. They reflect typical configurations used across many Model Year 2005–2009 RX400h vehicles, though exact figures can vary by market and trim.

• Nominal pack voltage: approximately 288 volts (often cited as ~270–300 V in various manuals and reviews)


• Usable energy capacity: about 1.2–1.3 kilowatt-hours (kWh)


• Battery chemistry: nickel-metal hydride (NiMH)


• Configuration: multiple NiMH modules arranged in series to reach the high voltage, with integrated cooling and control electronics

In practice, the capacity figure translates into a modest window for electric-only operation, with most daily driving relying on the Hybrid Synergy Drive to blend electric propulsion with the gasoline engine for efficiency rather than long-range electric driving.

Model-year considerations

While the RX400h used a consistent NiMH pack across its production run, minor engineering refinements and market-specific variants could slightly influence pack cooling, power management, and the perceived capacity. In general, though, the energy capacity hovered around 1.2–1.3 kWh for most RX400h units.

Context and impact

The battery’s relatively small energy capacity reflects its role as a supplemental energy source and a bridge to stop-start efficiency rather than a plug-in all-electric range vehicle. Owners may notice improved fuel economy and smoother transitions between electric assist and gasoline propulsion, especially in urban driving and light acceleration.

Summary

In short, the Lexus RX400h uses a NiMH battery pack with roughly 1.3 kWh of usable energy capacity, nominally around 288 volts, configured from multiple modules. This capacity supports hybrid assistance rather than long electric-only driving, with numbers that can vary slightly by model year and market.

What is the most common problem with the Lexus RX 400h?

Top 10 Common Problems in Lexus RX 400h and How to Fix Them

• Brake Actuator Malfunction.
• Cooling System Issues.
• Transmission (CVT) Problems.
• Faulty Oxygen Sensors.
• 12V Auxiliary Battery Problems.
• Dashboard Melting (Cosmetic Issue)
• Water Leaks in Rear Hatch or Sunroof.
• Suspension Wear and Noises.

How to check Lexus hybrid battery health?

You can check a Lexus hybrid battery's health by looking for dashboard warning lights, using the vehicle's on-board diagnostics menu, or by using a professional OBD2 scanner with a hybrid-specific app. For a thorough check, you can also manually measure individual cell voltages with a multimeter, but this requires advanced knowledge. 
This video explains how to use a professional OBD2 scanner to check your car's battery health: 1mMr.ElectricYouTube · Apr 7, 2020
Method 1: Use your car's on-board diagnostics 

• Turn the car to accessory mode (press the power button twice without your foot on the brake). 
• On the navigation screen, press the "Menu" button. 
• Turn the headlights on and off several times until the diagnostic menu appears. 
• Navigate to the "Function Check" or "Diagnostic" section to find the battery health report or voltage readings. 

Method 2: Use an OBD2 scanner and app 

• Plug an OBD2 scanner into the port under the dashboard. 
• Turn the vehicle on in "READY" mode. 
• Connect to the scanner via a smartphone app like Dr. Prius or Hybrid Assistant. 
• Navigate to the "HV Battery" monitoring screen to view detailed data. 
• Look for the following indicators:
  • Voltage: Healthy modules should be between 7.2V7.2 cap V7.2𝑉 and 8.4V8.4 cap V8.4𝑉. 
  • Internal Resistance: This should be uniform across all modules. 
  • Delta SOC (State of Charge): Avoid large gaps between module states of charge. 
• Be aware of error codes, such as P0A80 (Hybrid Battery Deterioration) or P3000 (Battery Control System Malfunction). 

This video demonstrates how to check your car's battery voltage using the on-board diagnostics menu: 1mViktor G AutomotiveYouTube · Aug 30, 2023
Method 3: Look for warning signs

• Pay attention to dashboard warning lights, such as the "Check Hybrid System" light or the general "Check Engine" light. 
• Listen for unusual noises from the battery cooling fan, which may indicate a cooling system issue. 
• Notice if the battery is draining or reaching a full charge more quickly than it used to. 

Method 4: Professional hybrid health check

• Schedule an annual "Hybrid Health Check" with a Lexus dealership or a qualified hybrid specialist.
• This check includes a comprehensive analysis of the hybrid battery, drive system, and cooling system to evaluate the overall health of the hybrid technology. 

What size battery is in the 2006 Lexus rx400h?

The 2006 Lexus RX400h uses a BCI Group Size 51R battery for its 12-volt auxiliary power. This size is a standard replacement, and you can choose from various options like conventional flooded or absorbed glass-mat (AGM) batteries with different cold cranking amps (CCA) and reserve capacities to fit your needs.
 
Battery size and specifications

• BCI Group Size: 51R
• Voltage: 12V
• Terminal location: Positive terminal is typically on the top-right front.
• Terminal type: SAE - Type A
• Dimensions (approximate):
  • Length: 9-5/16 inches
  • Width: 5-1/16 inches
  • Height: 8-15/16 inches 

Key considerations for replacement

• AGM batteries: These are often recommended for hybrid vehicles to provide reliable performance for the car's accessories, even when the engine is off. 
• CCA: Choose a battery with a CCA rating that meets or exceeds your climate's needs, though the 12V battery's role is less intensive than in a conventional vehicle. 
• Warranty: Look for batteries with a good warranty, as this can indicate durability and performance. 
• Hybrid system: Remember that the 12-volt battery is separate from the large, high-voltage hybrid system battery, which is a different component altogether. 

What is the battery capacity of the rx400h?

IMPROVED CELL CHEMISTRY: YES. RATED BATTERY CELL CAPACITY: 6.5 AH.