You finally bought a dash cam. You spent an hour tucking wires into the headliner of your car, feeling like a DIY pro, only to realize the damn thing turns off the second you pull the key out of the ignition. That’s the problem. Most people buy a dash cam for protection while driving, but they quickly learn that the most expensive "accidents"—hit-and-runs in grocery store parking lots or late-night vandalism—happen when the car is parked. If your camera is plugged into a standard 12V cigarette lighter, it’s basically a paperweight once you lock the doors.
That’s where the Garmin Constant Power Cable comes in.
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Honestly, it’s one of those "why didn't I think of this?" gadgets. Instead of making you tear apart your dashboard to find a fuse box and mess with "add-a-fuse" kits that look like a fire hazard, this thing just plugs into your OBD II port. Most cars made after 1996 have this port. It’s usually right under the steering wheel. You plug it in, and suddenly your dash cam has a direct line to the battery. It’s constant. It’s reliable. And it actually works without making you feel like an amateur electrician.
How the Garmin Constant Power Cable actually works
The OBD II port is usually reserved for mechanics to tell you why your "Check Engine" light is on. But it’s also a source of unswitched power. The Garmin Constant Power Cable taps into this to provide juice to your Garmin Dash Cam 47, 57, 67W, or the Mini 2.
Wait.
Won’t this kill my battery?
That is the first thing everyone asks. If you leave a camera recording 24/7, eventually you’re going to need a jump start, right? Garmin actually thought of that. The cable has a built-in timer switch and a voltage sensor. You can set it to stay on for 10 minutes, 24 hours, or just let it run indefinitely. But here is the kicker: if the cable senses that your car battery voltage is dropping too low—meaning you might not be able to start the engine—it cuts the power to the camera automatically. It sacrifices the surveillance to save the car. It’s a smart fail-safe that makes the whole "hardwiring" process feel a lot less risky for people who don't want to carry a portable jump starter in their trunk.
Installation is almost too easy
If you’ve ever tried to hardwire a dash cam the traditional way, you know the pain. You’re upside down in the footwell, using a multimeter to find a "hot" fuse, and trying to ground a wire to a rusty bolt. It’s a mess.
The Garmin Constant Power Cable is just a plug.
- Locate the OBD II port (usually near your left knee).
- Plug the cable in.
- Run the thin wire up the A-pillar.
- Set the timer.
That’s literally it. No wire stripping. No crimping. No blown fuses. It’s a five-minute job that gives you the exact same result as a professional $150 installation at a car audio shop.
Why parking mode matters for your insurance
Insurance companies are notoriously difficult when it comes to "unwitnessed" damage. If you walk out to your car and see a massive dent in the fender, it’s your word against the world. Without video evidence, you’re likely paying your deductible out of pocket.
The Garmin Constant Power Cable enables the "Parking Guard" feature on compatible Garmin cameras. Because the camera has a constant power source, it stays in a low-power standby mode. If the onboard G-sensor feels a jolt—like a bumper hitting your car—it wakes up instantly and saves the footage. If you have a Wi-Fi connection (like if your car is parked in your driveway), it can even send a notification to your phone.
Imagine getting a ping on your watch while you’re at dinner, seeing a live clip of a guy backing into your door, and walking out to catch him before he drives away. That is the actual value here. It isn't just about the tech; it's about the $500 or $1,000 you save on a deductible.
The weird limitations nobody mentions
Let's be real for a second. This isn't a perfect solution for every single person on earth.
First off, some European cars—looking at you, BMW and Volkswagen—can be real jerks about the OBD II port. Sometimes the car's computer realizes there is a power draw it didn't authorize and it might trigger a "battery discharge" warning on your dashboard. It’s not actually damaging the car, but the car is "worried" about the battery. Most of the time, the Garmin cable's low-voltage cutoff prevents this, but it’s something to keep in mind if you drive a sensitive German luxury sedan.
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Also, look at your port location. In some cars, the OBD II port is behind a plastic panel that won't close if something is plugged into it. You might need to buy a low-profile OBD II extension cable or just accept that the little door is going to stay open. It's a small aesthetic trade-off for 24/7 security, but for the "clean interior" fanatics, it might be a dealbreaker.
Another thing: if you have a hybrid or an electric vehicle (EV), the 12V battery system works a bit differently. While the Garmin Constant Power Cable generally works fine with them, the "voltage drop" logic can sometimes be slightly different because EVs tend to top up their 12V batteries from the high-voltage pack. It usually means the camera will run for a very long time, which is actually a plus.
Comparison: Constant Power Cable vs. Hardwire Kit
| Feature | Constant Power Cable (OBD) | Traditional Hardwire Kit |
|---|---|---|
| Install Time | 2 minutes | 45-60 minutes |
| Tools Needed | None | Multimeter, crimpers, fuse taps |
| Difficulty | Level 1 (Anyone) | Level 4 (Technical) |
| Reversibility | Instant (just unplug) | Requires removing fuses/wires |
| Compatibility | Most cars 1996+ | Any car with a fuse box |
The "Always On" vs. "Timed" debate
When you look at the physical box on the cable, you’ll see a little switch. This is where most people get confused.
If you set it to "Always On," you are relying entirely on the voltage cutoff. This is great if you drive every day. The camera will watch your car all night, and the battery gets recharged the next morning on your commute. But if you're leaving your car at the airport for a week, do not leave it on "Always On." Even with a cutoff, you're putting unnecessary stress on the battery.
Setting it to the 24-hour mark is usually the "sweet spot." It covers you for a full day of work or an overnight stay in a sketchy hotel parking lot, but then it shuts down to preserve your battery's long-term health. Batteries don't like being drained and recharged constantly; it shortens their lifespan. Using the timer is a smart way to be an "adult" about your car's maintenance.
Actionable steps for a better setup
If you’re going to pull the trigger on the Garmin Constant Power Cable, don't just plug it in and walk away. There are a few things you should do to make sure it actually works when you need it.
1. Check your MicroSD card. Constant recording or "Parking Guard" events take up space. If you are still using the tiny 16GB card that came with some older cameras, throw it away. Get a high-endurance card (like the SanDisk Max Endurance or Samsung Pro Endurance) that is at least 128GB. Standard cards will burn out in months under the stress of constant overwriting.
2. Test the voltage cutoff. After you install it, let the car sit overnight. Check the next morning to see if the camera is still on or if it timed out. You want to know exactly how your specific car battery handles the load before you rely on it in a high-stakes situation.
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3. Clean your windshield. It sounds stupid, right? But if your camera is recording 24/7, glare from a dirty windshield at night can make a license plate unreadable. Since the camera is now a permanent security guard, keep that little patch of glass spotless.
4. Update the firmware. Garmin frequently updates how "Parking Guard" handles sensitivity. Connect your camera to the Garmin Drive app and make sure it’s updated. Sometimes the cable needs the latest software to communicate correctly with the camera’s power management system.
The Garmin Constant Power Cable turns a simple dash cam into a full-scale security system. It removes the biggest barrier to entry—the "scary" installation—and replaces it with a simple plug. For about $50, it’s arguably the most cost-effective insurance policy you can buy for your vehicle. Just plug it in, tuck the wires, and stop worrying about what happens to your car when you aren't in the driver's seat.
Keep in mind that while this cable is designed for Garmin cameras, the dual USB outlet on the OBD plug actually provides standard 5V power. This means it can technically power other devices, but the "smart" features and communication for Parking Mode are specifically tuned for the Garmin ecosystem. Stick to the brand for the best results.
Check your car's OBD II location before ordering. Most are under the dash, but some (like certain Volvos) hide them in the center console or under a panel on the side of the dashboard. Knowing where it is will tell you if you need to plan for a longer cable run or a low-profile adapter. Once that's sorted, you're basically set for life.