Quick Summary:
- Confirm the engine is fully off, not left in accessory mode.
- Lock the car correctly, and check mirrors or lights confirm shutdown.
- Disable remote start or stop timed idling after warming up.
- Remove key fob from range, and close doors firmly.
Keyless ignitions are convenient in a New York car hire, but they can also make it easier to leave the vehicle in a state that quietly draws power. The most common causes are being stuck in accessory mode, not fully shutting down the infotainment, leaving a door or boot slightly ajar, or unintentionally keeping the car “awake” because the key fob remains nearby. In winter, remote start and long warm ups can also create confusion, because you may think the engine has stopped when it is still running on a timer.
This guide gives step-by-step checks you can do every time you park. It is written for common keyless systems found in airport rentals around New York, including pick-ups at New York JFK and Newark. The steps apply whether you collected via car hire Newark EWR or another local location, because the battery-drain risks are about how keyless cars behave, not the rental desk.
1) First, understand what actually drains the battery
A modern hire car can drain its 12V battery while parked for four broad reasons:
Accessory mode left on. If you press the start/stop button without your foot on the brake, many vehicles enter ACC or ON mode. The screen, radio, USB ports, and sometimes climate fan can continue drawing power.
Vehicle never fully goes to sleep. A key fob left near the car, an open app session in the infotainment, or an active proximity sensor can keep modules awake longer than normal.
Something is physically open. A door not latched, the boot not fully closed, or even a glovebox or vanity mirror light can stay on. Some lights are hard to see in daylight.
Cold weather reduces usable battery capacity. New York winter temperatures reduce battery performance, so a small drain that would be fine in summer becomes a no-start the next morning.
2) Step-by-step shutdown check, do this before you exit
Use this exact sequence each time you park, especially if you have been stopping frequently for loading, photos, or quick errands.
Step 1: Come to a complete stop and shift to Park. On automatics, make sure the selector is firmly in P, not hovering between gears. Some vehicles will not fully shut down if they are not in Park.
Step 2: Keep your foot on the brake and press the start/stop button once. The brake pedal is the difference between “engine off” and “accessory toggle” in many models. If you press the button without the brake, you can end up in accessory mode.
Step 3: Look for clear engine-off indicators. Check the tachometer is at zero (if fitted), and the dash no longer shows “READY” (common in hybrids). Also listen for the fan and engine note disappearing. In a quiet garage you will notice it immediately, on a busy Manhattan street you may need the visual check.
Step 4: Make sure the infotainment screen goes dark. Some systems stay lit for a minute, but most will dim or show a “Goodbye” screen. If the screen stays fully bright indefinitely, you may still be in ACC.
Step 5: If you are unsure, force a full power down. With your foot on the brake, press and hold the start/stop button for a couple of seconds. Many vehicles treat a long press as a definitive off command.
Step 6: Open the driver door and confirm the car complains if it is still on. If the car is running or in ON mode, most models will chime loudly when the driver door opens. No chime does not guarantee everything is off, but a strong warning chime is a red flag that you need to shut down properly.
3) Avoid the accessory mode trap, the most common battery killer
Accessory mode is easy to trigger when you are charging phones, using the navigation, or waiting briefly. In a car hire, it is also common when you stop to check directions and press the button thinking you are switching off.
To avoid ACC drain:
Do not “double-press” the start/stop button. Some cars cycle OFF, ACC, ON with repeated presses. If you press once with no brake, then again, you can end up in ON mode while the engine remains off, which drains the battery fastest.
Use the cabin timer if available. Some vehicles have an “auto-off” timer for accessories. If you find it in settings, enable the shortest practical timer while travelling.
Charge devices while driving, not while parked. USB ports and 12V sockets can remain live in ACC. Charging a tablet, powering a dashcam, or running a hotspot for an hour can be enough to cause trouble in cold weather.
Do not leave a dashcam plugged in unless you are sure it is ignition-switched. Many rental cars have always-on USB ports. If your dashcam has “parking mode”, it can drain the battery overnight.
4) Lock correctly, because an unlocked keyless car may stay awake
Keyless systems can behave differently depending on how you lock the vehicle. Relying on “walk-away lock” is risky because it might not trigger if a door is not fully shut, or if the fob remains inside the car.
Use this locking routine:
Step 1: Close all doors firmly, then check the boot. If you are carrying luggage from an airport pick-up, the boot is the most common culprit. Push down gently after you hear the first latch click to ensure it is fully seated.
Step 2: Lock using the key fob button or the door handle sensor. Wait for a positive confirmation, usually a beep or the indicators flashing.
Step 3: Confirm by testing the door handle. After two or three seconds, pull the handle. It should remain locked. This is a quick way to avoid coming back to an unlocked car that stayed awake.
Step 4: Watch for signs the car is still “alive”. Mirrors may remain unfolded, puddle lights may stay on, or the cabin screen may remain illuminated. These hints vary by model, but if anything looks wrong, unlock and repeat the shutdown and lock steps.
If you collected your vehicle via an airport desk, the same advice applies whether you are in Queens at Avis at JFK or using another provider. The key is to get a clear lock confirmation rather than assuming the car did it automatically.
5) Keep the key fob away from the car when parked
A surprisingly common cause of battery drain in keyless vehicles is leaving the key fob close enough that the car keeps “handshaking” with it. In apartments, this happens when you park on the street outside and hang the keys near the front door. In hotels, it can happen if your room is directly above the car park.
Practical distance rule: keep the fob at least several metres away from the vehicle, ideally not against the wall closest to the parking spot. If you are staying in a New York hotel with valet parking, keep the fob away from windows facing the street-side parked car.
Do not leave the fob in the vehicle. Many cars will warn you, but not all. If the fob is inside, the car may remain unlockable, may refuse to lock, or may stay awake longer.
Use a signal-blocking pouch if you already have one. It is not essential, but it can prevent the vehicle from repeatedly waking. If you use one, test it by standing next to the locked car and confirming it will not unlock.
6) Cold-weather remote start, make sure it is actually off
In New York winter, drivers often use remote start to warm the cabin and defrost. On some models, remote start runs for 10 to 15 minutes, then stops automatically. On others, it can be extended. The problem is that you can misread what happened, especially if you are indoors and cannot hear the vehicle.
Use these safeguards:
Step 1: Know your vehicle’s remote start behaviour. If the rental agent mentioned remote start, ask whether it shuts off automatically, and how to cancel it. This is particularly useful when collecting from Dollar at Newark EWR or similar winter-heavy locations.
Step 2: Do not repeatedly remote start without driving. Multiple warm-up cycles can drain a weak battery faster than one longer drive, because each start uses high current.
Step 3: After entering, complete the “takeover” properly. Many cars require you to press the brake and hit start to transfer from remote start to normal driving. If you do not, the engine may shut off unexpectedly when you shift, or you may cycle the system into accessory mode while you fiddle with settings.
Step 4: When you park, shut down as if remote start never happened. Follow the shutdown steps in section 2. Do not assume that because the car was remote started earlier it will be in a normal state now.
7) Check hidden drains: lights, climate, and connected tech
Even if you shut down correctly, a small “hidden” load can flatten a battery overnight in cold conditions.
Interior lights: Set the interior light switch to “Door” rather than “On”. Check the boot light and glovebox light are off. If you see a faint glow after closing the car, reopen and look for a stuck switch.
Seat heaters and rear demister: These usually turn off with the car, but if you are sitting in ACC for a while, they can draw meaningful power.
Aftermarket plugs: Remove phone chargers, inverters, and anything in the 12V socket. Some adapters have LEDs that draw power continuously if the socket remains live.
Bluetooth and Wi-Fi: A car that is waiting to connect to a known phone can sometimes stay awake longer. If you are troubleshooting unexplained drain, forget the phone from the car’s Bluetooth list during the rental period, or at least turn off the car’s Wi-Fi hotspot feature.
8) If you suspect the battery is already weak, reduce risk immediately
Hire cars are generally maintained, but a battery can still be marginal, especially after lots of short trips in traffic with heavy accessory use.
Take a longer drive. A steady 30 to 60 minute drive can recharge a 12V battery better than multiple short hops. This matters in New York, where stop-start traffic and short distances can prevent full charging.
Limit accessory time with the engine off. If you must wait in the car, consider keeping the engine running briefly rather than sitting in ACC for long periods. Be mindful of local idling rules and safety considerations.
Watch for warning signs. Slow cranking (non-hybrid), dimming lights, or repeated “low battery” messages mean you should avoid short stops with accessories on.
Know your support route. If the car will not start, follow the rental provider’s roadside assistance instructions. Do not attempt complex DIY fixes beyond basic jump-start procedures you are comfortable with, and avoid disconnecting the battery in a modern vehicle unless instructed, because it can trigger security and infotainment lockouts.
9) Parking habits in New York that prevent drain
City parking adds its own wrinkles. Tight kerb spaces can mean doors do not open fully, so they do not close fully either. Street noise can hide warning chimes. Cold snaps can turn a borderline battery into a no-start quickly.
Do a final 10-second walkaround. Check the car is dark inside, no lights remain on, and it is visibly locked. This is especially useful at night when you can easily spot an interior light.
Avoid leaving the car “half-locked”. If the car beeps repeatedly when you lock, or the indicators do not flash, something is wrong. Unlock, close everything again, and lock with a clear confirmation.
If you are using airport parking or a hotel garage, tell attendants it is keyless. Miscommunication can lead to the car being left in ACC. Make sure the attendant knows the key must be removed from the vehicle and stored away from it.
If you are comparing pick-up points for a future trip, Hola Car Rentals has pages for Hertz at JFK and other options, which can help you understand typical vehicle types and keyless features you might encounter.
FAQ
Q: How can I tell if my keyless hire car is in accessory mode?
A: If the dashboard and infotainment stay on with the engine off, or the radio plays after you “switched off”, it is likely in ACC. Press the start/stop button with your foot on the brake to fully shut down.
Q: Does leaving the key fob near the car really drain the battery?
A: It can. Some vehicles keep sensors and modules awake when they repeatedly detect the fob nearby. Store the fob well away from the parked car, especially overnight in cold weather.
Q: I locked the car, but the next day it was flat. What should I check first?
A: Start with simple drains: interior lights, boot not fully shut, a charger or dashcam plugged into a live socket, or the car left in ACC. Then consider cold temperatures and lots of short trips as contributing factors.
Q: Is remote start safe to use in New York winter without draining the battery?
A: Occasional remote start is usually fine, but repeated warm-ups without driving can weaken the battery. Ensure you cancel remote start when you do not need it, and fully shut down the vehicle after parking.
Q: Should I leave the engine idling instead of using accessory mode?
A: For short waits, idling can prevent battery drain, but be mindful of local idling restrictions, fuel use, and safety. If you are waiting longer, it is better to switch off fully and minimise accessory use.
