Quick answer: Battery Replacement on a 2016–2022 Lexus RX is rated Moderate and takes about 20–30 minutes. You'll need 4 tools for this job, and parts cost about $140. This guide walks you through the full job step by step, including the mistakes to avoid.
| Part Name |
Part Number |
Price |
Buy |
| Correct group-size battery |
— |
$140.00 |
|
| Terminal cleaner Optional |
— |
$8.00 |
|
| Terminal protectant Optional |
— |
$7.00 |
|
About prices: shown prices are typical retail averages and change frequently; cheaper alternatives may be available. Confirm the current price before buying.
💡 Pro tip: Order all parts at once to save on shipping
Step-by-Step Instructions
Follow these steps carefully
1
Park it and shut it down
Park on level ground, switch everything off, and take the key fob with you. Do not confuse the hybrid's small 12-volt auxiliary battery with the big high-voltage traction battery; you are only touching the 12-volt one.
🔧 Mechanic's note — Tom Becker
In my experience this matters: Do not confuse the hybrid's small 12-volt auxiliary battery with the big high-voltage traction battery; you are only touching the 12-volt one.
2
Expose the battery
On the RX350, open the hood and lift off the plastic battery cover — it unclips. On the RX450h, lift the luggage-compartment deck board and remove the battery cover on the left side.
3
Disconnect the negative cable first
Loosen the 10mm nut on the black negative (–) cable clamp and wiggle the clamp off the terminal post. Tuck the cable aside so it cannot spring back and touch the post.
4
Disconnect the positive cable, then the hold-down
Loosen the 10mm nut on the red positive cable and lift the clamp off its post. Then remove the battery hold-down — on these Lexuses it is a clamp bar across the top of the battery secured by a bolt.
5
Lift out the old battery
Batteries weigh around 40 pounds, so lift with your legs, keep the battery upright, and do not tip it — spilled acid burns skin and paint alike.
🔧 Mechanic's note — Tom Becker
I always double-check this: Batteries weigh around 40 pounds, so lift with your legs, keep the battery upright, and do not tip it — spilled acid burns skin and paint alike.
6
Drop in the new battery and connect positive first
Reinstall the hold-down clamp so the battery cannot shift or bounce. Then connect the positive cable first and tighten its 10mm nut, then the negative — this reverse order is what keeps you from shorting a wrench to ground.
🔧 Mechanic's note — Tom Becker
Have the parts counter match the replacement to your exact year and trim; never guess at size or cranking amps. I don't skip this anymore.
7
Start it up and check everything
Start the vehicle and confirm it cranks briskly and idles. After a battery swap, some RXs need the power windows re-learned — run each window fully down and then fully up once — and the clock may need resetting.
All Done!
Test your repair before closing everything up. If something doesn't work right, double-check your steps.
⚠️ Common Mistakes to Avoid
- • Disconnecting the positive cable first and shorting the wrench against the body
- • Installing the new battery with reversed terminal orientation
- • Forgetting the hold-down clamp and letting the battery bounce around
