If you are searching “why does my car key battery keep dying” or “why does my key fob battery keep dying”, you are not the only one. A key fob battery that keeps going dead usually points to one specific issue – and most of the time you can fix it without replacing the whole fob.
This guide covers the most common causes, the fastest checks, and the fixes that actually work long-term. It also answers “why does the battery in my car key keep dying” and “why does my key fob battery die so quickly” with real troubleshooting steps.
Common reasons a key fob battery keeps dying
- The battery is low quality or old stock
This is the #1 reason people say “my key fob battery keeps dying”. Many cheap multipacks are old, stored poorly, or inconsistent. The battery can test “okay” at first and still fail fast under real use. - The battery is not making solid contact
If the battery can wiggle even slightly, the fob may lose power intermittently and draw power inefficiently. Bent or flattened contacts are common after a battery swap. - The fob is constantly waking up (stored too close to the car)
If you keep the key near the car (garage wall, entryway table near the driveway, or close to the vehicle overnight), some proximity systems keep “handshaking” or waking up more often than needed. That can drain the battery much faster. - A button is stuck or being pressed by the case
A slightly jammed button (or a case that presses a button just enough) can cause constant transmit attempts. This is a classic reason for “why does my key fob keep dying”. - Dirt, corrosion, or moisture inside the fob
Skin oils, dust, and humidity can create small leakage paths on the board. If there is any corrosion, battery life can drop from years to weeks. - The battery was installed wrong
Some fobs can still close with the battery upside down or not seated correctly. Sometimes the cover pinches the battery and the contacts do not sit flat. - The fob itself has an internal fault
Cracked solder joints, a failing transmitter, or water damage can increase power draw. If you have done everything else and it still drains fast, it is usually the fob.
Useful table – why your key fob battery keeps going dead (and what to do)
| Symptom | Most likely cause | Quick check | Best fix | Result you should expect |
|---|---|---|---|---|
| Battery dies in 1 to 4 weeks | Bad or old battery stock | Swap to a fresh name-brand battery from a reputable store | Use quality battery + avoid old multipacks | Often fixes it immediately |
| Battery works, then randomly stops, then works again | Loose fit or weak contacts | Shake test – if it rattles, contacts are not tight | Gently bend contacts up (slightly) + re-seat battery | Restores stable power and normal life |
| Battery drains faster when parked at home | Key stored too close to the car | Move key 20-30 ft away for a week | Store farther away (or use a Faraday pouch if needed) | Battery life improves noticeably |
| Battery dies after you dropped the key or changed the shell | Button stuck or case pressing a button | Press each button – any feels sticky or always “down”? | Clean buttons, realign rubber pad, replace shell if warped | Stops constant transmitting |
| White/green residue inside or battery looks crusty | Corrosion or moisture | Look at battery tray and metal contacts | Clean with isopropyl alcohol, dry fully, replace battery | Can restore normal life if damage is mild |
| Battery died right after replacement | Battery installed wrong or wrong size | Double-check polarity and seating | Install correct type, ensure it sits flat | Fixes “dies immediately” cases |
| You replace battery and it still drains fast | Internal fob fault | Try a new battery + store far away – still dies? | Repair or replace fob, or test with a locksmith | Confirms it is not “just batteries” |
Step-by-step troubleshooting (fast order)
Step 1 – Use a better battery first
If you are asking “why does my key fob battery keep dying”, start here. Put in a fresh name-brand battery and avoid old bulk packs. Make sure it is the exact type your fob uses.
Step 2 – Check the fit and contacts
The battery should sit flat and feel snug. If it moves, the contacts may be flattened. A tiny adjustment makes a big difference. If you are not comfortable bending contacts, a locksmith can do it quickly.
Step 3 – Move the key farther away from the car for 7 days
This is the easiest way to test the “constant wake-up” problem. If battery life improves, your fix is simply storage distance (or a Faraday pouch).
Step 4 – Check for stuck buttons
Take the case apart and make sure no button is jammed. Also check if an aftermarket shell is pressing on the rubber pad.
Step 5 – Inspect for moisture or corrosion
Any residue is a red flag. Clean gently with isopropyl alcohol and let it dry fully before inserting a new battery.
Step 6 – If it still drains fast, the fob likely has a fault
At that point, it is usually not user error. A locksmith can test the fob’s power draw and confirm if replacement is the best route.
How long should a key fob battery last?
In normal conditions, many key fob batteries last around 1-3 years depending on the vehicle, key type (proximity vs standard), and how often you use it. If yours dies in weeks or a couple months, that is not normal – it usually means one of the issues above.
Quick habits that extend battery life
- Do not store the key right next to the car
- Avoid cheap multipacks and unknown battery brands
- Do not leave the key in a tight pocket with pressure on buttons
- Replace cracked shells that press buttons
- Keep the battery contacts clean and snug
