Is the Fi Series 3+ Collar Worth Buying?

Fi Collar recently updated to the latest Fi Series 3+ Smart Dog Collar a few months ago. How does it compare to the older Fi Series 3? Is it worth buying or upgrading to?

According to Fi’s official announcements,

The Fi Series 3+ takes everything you love about the Series 3 and levels it up. The main improvements are:

• Faster, Smarter Tracking: Equipped with an enhanced antenna, the Series 3+ delivers 2x faster and more accurate GPS Tracking. This means quicker updates when your dog is on the move – whether you’re exploring new trails or responding to an unexpected escape.
• AI-Powered Behavior Tracking: Series 3+ is the first device to detect steps, sleep, barking, licking, scratching, eating, and drinking – unlocking a comprehensive view of your dog’s wellness and daily routines.

You can find the specific feature updates in the table below:

Features	Series 3	Series 3+
GPS Tracking	✅	2x improved GPS tracking
Lost Dog Mode	Location updates in real-time	Location updates in real-time and 2x improved GPS tracking
Health Tab Access	Activity + Rest	Activity + Rest and AI Behavior Tracking + Insights
Behavior Tracking (AI)	🚫	Eating, Drinking, Barking, Licking, and Scratching
Apple Watch Integration	🚫	✅
Battery Life	3 Months	3 Months
Waterproof	✅ rated both IP68 and IP66K	✅ rated both IP68 and IP66K
Extended Warranty	✅	✅

To see if it really performs as promised, I tried it out myself.

Here are my thoughts on the new Fi Collar 3+ from my own experience.

Compact Design and Solid Build Quality—Perfect for Tiny Dogs

The stainless steel Fi device itself weighs just 0.95 ounces (about 25 grams) without the collar.

According to the sizer on Fi’s website, it fits dogs as small as 5 pounds with a minimum neck size of 9.5 inches. Compared to other GPS collars on the market, it’s rare to find one that actually works for toy breeds.

While it’s too early to judge its long-term durability, the Series 3+ is a little thinner and looks to be made well. I haven’t had issues with my old ones and they have gotten the heck beat out of them too and I haven’t needed to replace them.

One thing to note: the Fi can’t be attached to just any collar—you either have to use the one it comes with or buy one of the many available third-party “Fi-compatible” option on amazon (one of which might better suit your style).

Reliable Location Tracking

Real-time tracking is the heart of any GPS collar, and the 3+ delivers.

Based on my tests, if I walk our dog with the collar Bluetooth-tethered to my phone, I get a very accurate track. Both the data points themselves, and the frequency of data points, to provide a reasonably high resolution track. I don’t actually care about that use case because I don’t need GPS to tell me my dog is walking next to me.

When someone else walks my dog in the same area, Fi collar using its own LTE/GPS, the GPS accuracy seems similar but the frequency of data points transmitted is far less, and the track is much lower resolution (a series of long straight connected lines).

“Lost Dog Mode”: A Major Upgrade

I also tested “Lost Dog Mode,” which prioritizes update frequency over battery life. Last year, Fi upgraded this feature to refresh every 10 seconds.

I tested the Fi 3+ against the Fi 2 on my three dogs: Odin, Nix, and Pandora. The performance gap was clear.

While I could watch Odin and Nix (on the 3+) move in real-time, Pandora is wearing the F2 and hers obviously isn't as accurate and slow to update. The 3+ also tracked down into the gully further which turns into a dead zone in the woods.

Bottom Line: The Fi 3+ provides much more precise and timely tracking when it matters most. Since “Lost Dog Mode” is a battery hog, I recommend activating it the second you realize your dog is missing.

Smart Power Management and Impressive Battery Life

Unlike any other tracker we tested, the Fi comes with a separate base that helps maximize battery life.

“When your dog is inside your home, it’s going to connect to the base via Bluetooth Low Energy. And that connection is super cheap from an energy perspective,” said Jonathan Bensamoun, Fi’s CEO and founder.

The base also serves as a wireless charger, using magnetic induction.

In my real-world testing, the new Series 3+ has shown even better stamina. I’ve had it running for five days now, and my puppy’s Series 3+ is still sitting at 93%. In contrast, my older dog’s Series 3 is at 84%, even though both were fully charged last Sunday.

While official claims suggest up to three months of battery, the general consensus on Reddit is that it typically lasts between 2 to 2.5 months on a full charge. Even if it doesn't always hit that three-month mark, it’s still standout performance compared to the competition.

Comprehensive Behavior & Health Tracking

While the original Series 3 covered the basics, the upgraded Fi Series 3+ delivers a much deeper dive into your dog’s well-being through a cleaner, more intuitive interface.

It moves beyond traditional metrics like sleep, barking, and activity. The Series 3+ now provides a holistic view of your dog's health by tracking eating, drinking, licking, and scratching habits—giving you early insights into potential health issues before they become serious.

According to Fi, the AI behavior detection feature is designed to improve over time. As more models are trained, the system will continue to refine its accuracy—potentially detecting issues with your dog even before you notice them.

Flaws but not dealbreakers

It’s slower to activate live tracking — but it’s getting better.

The biggest problem we had when we first tested the Fi was how long it sometimes took to activate live tracking. But the company has continued to improve on this metric. With the new Series 3+, we noted an average connection time of 27 seconds, a nearly 30% improvement from its previous average of 38 seconds.

It’s intended to work with the app always running in the background.

I regularly quit out of all the apps on my phone, partly to preserve my battery and partly to preserve some semblance of privacy. But whenever I closed the Fi app, it pushed a message saying I should leave the app open in the background “for better tracking.” According to Bensamoun, if you’re walking your dog with the app closed, the collar won’t know that you’re actually with your dog, and it will think they’re escaping. It will then power up the GPS connection and start sending you alerts, all of which will drain the battery faster. Bensamoun assured us that you don’t have to leave the app open in order for the tracker to function, but it works better if you do.

Reliable Customer Service

I’ve reached out to Fi’s support team multiple times with product questions, and they’ve consistently been patient and helpful.

I even came across a Reddit thread where a user had issues with false “out-of-safe-zone” alerts on their new Series 3+. Fi’s team worked closely with them via email and phone until the issue was fully resolved.

From my experience, their support is genuinely dependable. You don’t have to worry about being left in the lurch if a technical glitch occurs—they will stick with you to find a solution.

Also, keep in mind that Fi offers a 30-day return policy, though return shipping is on the customer.

The Verdict: Is the Fi Series 3+ Worth It?

Yes. The Fi Series 3+ is a significant leap forward, transitioning from a basic GPS tracker into a comprehensive, AI-powered health and safety wearable.

• For Series 3 Users: The upgrade is worth it if you want deeper health insights (like monitoring eating, drinking, or scratching) or if your current battery is starting to show its age.
• For New Buyers: This is arguably the most well-rounded smart collar on the market, especially for small dog owners and those who prioritize long battery life.
• For Series 2 Users: An upgrade is a no-brainer. The improvements in “Lost Dog Mode” speed and the addition of health metrics are night-and-day differences.

Final Thoughts: The Fi Series 3+ isn't just about finding your dog if they escape; it’s about preventative health. The ability to catch a spike in scratching or a drop in water intake via AI makes it a proactive tool for your dog’s well-being. Coupled with solid customer service, it’s a low-risk, high-reward investment for any pet parent.