Quick answer: Battery Replacement on a 2015–2020 Acura TLX is rated Easy and takes about 1 hour. You'll need 5 tools for this job, and parts cost about $168. This guide walks you through the full job step by step, including the mistakes to avoid.
| Part Name |
Part Number |
Price |
Buy |
| 12V AGM Battery |
— |
$150.00 |
|
| Battery Terminal Cleaner |
— |
$10.00 |
|
| Battery Terminal Protector Spray |
— |
$8.00 |
|
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
Prepare the vehicle
The 2015–2020 Acura TLX has its battery in the ENGINE BAY on the driver side. You'll need: Group 24F AGM battery (idle-stop equipped — check your original), 10mm socket. No registration needed. Note: the TLX has a battery current sensor on the negative terminal (same as the MDX) — handle it carefully during removal. The sensor monitors charging for the idle-stop system. After disconnecting, expect radio presets to reset and the idle-stop may need a drive cycle to recalibrate.
2
Disconnect negative first
Open the hood and locate the battery. Always disconnect the NEGATIVE terminal first. Use a 10mm wrench to loosen the clamp. Be gentle — don't yank the cable or damage the sensor. The sensor is critical for the idle-stop system; damaging it will cause warnings.
🔧 Mechanic's note — Ray Delgado
In my experience, that current sensor on the negative terminal is the idle-stop system's brain — treat it like glass. Yank the cable and you'll be chasing phantom warnings that only a new sensor fixes.
3
Remove the hold-down
Remove the battery hold-down. The TLX uses the Honda/Acura J-hook + top bar design. Apply penetrating oil if seized. Remove the top bar. Keep all hardware. Note the battery orientation. Verify your original is AGM (it should be for idle-stop) — check the label.
4
Lift out the old battery
The Group 24F AGM is heavier than flooded. Note the orientation. Place on a flat surface. Verify your replacement: Group 24F AGM. Do not install a flooded battery — the TLX's idle-stop system requires AGM. The charging profile is calibrated for AGM chemistry.
🔧 Mechanic's note — Tom Becker
I've found that AGM only — do not install a flooded battery in this car. The charging profile is calibrated for AGM chemistry, and a flooded battery in an idle-stop TLX dies young and throws warnings.
5
Clean the tray and terminals
Clean the battery tray. Remove corrosion and debris. Clean the terminals with a wire brush. Inspect the battery current sensor on the negative cable — ensure it's clean and undamaged. Check the J-hooks and top bar. The tray should be dry and clean.
6
Install the new battery
Place the new Group 24F AGM battery in the tray, matching the original orientation. Reinstall the top bar and J-hooks. Tighten snugly. Ensure the battery current sensor will align properly with the negative post. Double-check terminal positions. The battery must be secure.
7
Reconnect positive first
Reconnect the POSITIVE terminal first (red, plus), tighten the 10mm clamp. Then reconnect the negative with the current sensor — ensure it seats properly. Apply dielectric grease. No registration needed. The sensor will automatically recalibrate after a few drive cycles.
8
Verify and complete
Close the hood. Start the vehicle. Verify all systems. The idle-stop may not work immediately — it needs a drive cycle to recalibrate to the new battery. Check for warning lights. If idle-stop doesn't engage after several days, have the battery sensor checked.
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 terminal before the negative terminal
- • Not securing the new battery properly
- • Failing to check the battery's charge level after installation
