How To Replace A Lexus RX350 Battery?

Replacing a Lexus RX350 battery involves locating the 12V AGM battery under the hood, disconnecting terminals (negative first), removing the hold-down bracket, and installing an OEM-compatible replacement. Critical steps include wearing safety gear, avoiding terminal contact, and torquing connections to 5–7 Nm. Dispose of the old battery at certified centers—incorrect handling risks acid leaks or electrical faults.

12V LiFePO4 Batteries

Where is the Lexus RX350 battery located?

The RX350’s 12V battery sits under the hood, typically on the driver’s side. Secured by a metal bracket, it connects via red (positive) and black (negative) terminals. Newer models (2016+) often position it near the firewall to optimize space.

To access the battery, lift the plastic cover and unscrew the hold-down bracket with a 10mm socket. Pro Tip: Check your owner’s manual for exact placement—hybrid models relocate the 12V battery to the trunk. For example, a 2020 RX350 Hybrid’s auxiliary battery is behind the rear seat, requiring trim removal. Transitioning from ICE to hybrid designs, Lexus prioritizes weight distribution, which impacts battery location. Always disconnect the negative terminal first to prevent short-circuiting nearby electronics.

What safety gear is needed for battery replacement?

Essential safety gear includes acid-resistant gloves, safety goggles, and a non-conductive apron. These protect against corrosive electrolyte spills and accidental shocks from live terminals.

Battery acid can cause severe burns, so nitrile gloves (0.3mm+) are mandatory. Safety goggles prevent splashes during terminal cleaning—a 50/50 baking soda/water mixture neutralizes corrosion. Practically speaking, a fire extinguisher rated for electrical fires (Class C) should be nearby. For instance, a technician once avoided a thermal incident by keeping a 5lb extinguisher within reach. Pro Tip: Never wear metal jewelry; a wedding ring contacting both terminals can draw 500+ amps, melting skin tissue instantly.

How do you safely remove the old RX350 battery?

Disconnect the negative terminal first using an 8mm wrench, then the positive. Remove the hold-down bracket and lift the battery (15–20kg) at a 45° angle to clear cables.

Post-2015 models have Battery Monitoring Systems (BMS) that require resetting after replacement. Use a plastic pry tool to avoid scratching terminals. If terminals are corroded, apply baking soda paste and scrub with a brass brush. For example, a 2018 RX350 with heavy corrosion needed terminal replacement after acid ate into copper wires. Transition carefully—tilting the battery too far risks spilling electrolyte. Pro Tip: Wrap terminals in cloth to prevent accidental contact while moving the old battery.

What steps ensure proper installation of the new battery?

Clean the tray with baking soda solution, position the new battery, and secure the bracket to 5–7 Nm torque. Reconnect positive terminal first, then negative, and apply anti-corrosion gel.

Lexus specifies AGM batteries (Absorbent Glass Mat) for RX350s post-2010—flooded lead-acid types risk overcharging. Terminal bolts should be torqued to 5.4 Nm using a calibrated wrench. Post-installation, test voltage: a healthy AGM battery reads 12.6–12.8V static. For example, a 2022 RX350’s new battery showed 12.4V, requiring alternator testing to confirm charging issues. Moreover, reset the BMS via the OBD-II port to ensure accurate charge monitoring. Transitioning to maintenance, avoid over-tightening terminals, which can strip threads.

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How to maintain your new Lexus RX350 battery?

Monthly inspections for corrosion, secure connections, and 12.4V+ voltage extend lifespan. Use a multimeter to check charge levels and clean terminals biannually.

AGM batteries last 4–7 years if maintained. Avoid draining below 12V—deep discharges below 50% capacity permanently damage cells. For instance, an RX350 left idle for two months dropped to 11.8V, requiring a recharge at 10A for four hours. Transitioning seasons affect performance; winter demands 20% higher charge. Pro Tip: Use a trickle charger during storage—CTEK MXS 5.0 maintains 13.6V without overcharging. If voltage dips below 12.2V, test the alternator’s 14.2–14.7V output.

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