How to replace the battery in a Garmin Fenix 5 Plus watch

The Garmin Fenix 5 Plus was released in 2018 and is still a great running watch in 2023. Some features include heat rate tracking, VO2 max, recovery advisor, payments and offline music. There's also my favorite: offline maps and navigation.

When I bought a used Fenix 5 Plus on eBay four years after it was released, the battery would still last 19 hours in GPS tracking mode, and several days as a smart watch.

The build of the watch is also very durable. It's made with a steel body, while some models are made with titanium and sapphire.

And importantly for this post: Garmin Fenix watches are repairable. the body is easily opened with a T6 Torx screwdriver.

Considering the Garmin Fenix 5 Plus is available for around $150 on eBay these days, this is still a great deal on a running watch!

I believe the same tools and process are also used for the Fenix 3, 5, 5X and 5X Plus, but haven't tested with other models.

Tools needed

• A T6 Torx screwdriver
• Something to carefully ply the glued battery out with, like the iFixit Opening Pick.

Parts needed

• The battery part number is 361-00097-00. The original has a voltage of 3.8v. The capacity is 255 mAh. A replacement may have a larger or smaller battery capacity as long as it physically fits. I recommend one getting one advertised as "new", because used batteries can be hit-and-miss. I'm in the United States, so I tried the "Garmin Approach S60 Fenix 5 230 mAH Smart Watch Replacement battery" from Battery Clerk. (Not an affiliate link!). It was $23.66 with shipping to Indiana. What's important is that:
  • 1. ✅ The part number matches
• 2. ✅ The physical dimensions fit
• 3. ✅ The electrical specs are compatible
• 4. ✅ It looks close enough to the one I pulled out of my watch.
• If you want to try another vendors, besides searching for Garmin part number "361-00097-00", you can also try searching for the Model number used by Cameron Sino, the replacement battery manufacturer: CS-GMF500SH. Just make sure all the details match!

Installation

There are already good videos on YouTube about the installation process so I won't make yet another. The process boils down to this:

1. Power off the watch if you haven't already ready.
2. Open the back of the watch with a T6 Torx screwdriver. (On the 5X, apparently you open the front instead)
3. Carefully disconnect the back and battery from the battery.
4. Carefully pry up the old battery
5. Install the new battery.
   1. Here, the replacement battery was just slightly larger than the original. At first, it appears some of the foil cover of the battery wasn't going to fit, or that the wires might not fit, but by using the same plastic "opener" picker" to press on the edges a bit, I was able to solve the fit problems in a couple of minutes.
6. Reconnect the battery and the watch back
7. Replace the bolts.
   1. I recommend not fully tightening the bolts until you have tested powering on the watch. If it doesn't power own, you might need to re-check your connections or try charging the watch.

The whole thing could be done in about 5 minutes.

Details about the Fenix 5 Plus replacement battery

How long does it take for the battery to arrive?

It took ten days to get the shipping notification from BatteryClerk.com, but then the battery arrived two days later in Indiana. So twelve days later. I suspect the battery was also shipped from China.

Does the Fenix 5 Plus replacement battery have a warranty?

The battery I received was manufactured by Cameron Sino, which specializes in replacement batteries, but does not seem to sell direct to consumers. The battery came in a box that said it had a one year warranty with some standard disclaimers against standard wear and tear and so forth.

Will the Garmin Fenix 5 Plus be waterproof after replacing the battery?

I presume so, but I provide no warranty! There's a rubber seal in between the body and bottom of the watch that's squeezed when the bolts are tightened. The quality of the seal does not appear compromised by opening and replacing the bottom of the watch.

How long does a replacement battery for a Garmin Fenix 5 Plus last?

I tested the battery life of the new battery the same way I tested the original when I first got it: I started tracking a run with GPS and heart rate enabled and left it in a window sill until the battery died. Then when I found it and booted it, I checked now long the activity was.

The original battery, which was about four years old when I bought the watch used, could track a 19 hour GPS activity. The replacement battery tracked for 20 hours and 25 minutes in GPS mode. Even longer!

Shortly after I bought the Fenix 5 Plus I tested the battery with real-world conditions on a 50 mile run that required about 11 hours of tracking including using some of the maps and navigation and it still had 25% or so of the battery left.

Mistakes I made

• I bought a replacement battery on eBay that also included the watch back. The price was practically the same as getting the battery by itself, so why not get them both and make installation easier? I found out. First, there was a long wait for the package to arrive from China. Then I saw they sent me a steel back, while I ordered Titanium. Finally, the watch still didn't boot with the new battery. I suppose it was an old, used battery that already died as well. But, "win or learn". I learned that the battery could be easily be pried off and buying the battery with the back was not necessary– indeed it would be better to have a "new" battery than this result.
• I saw that printed on the original battery was "Model: ASDB402334-P1" and assumed that's the primary model number. This leads to far fewer search results for replacements. I suspect that may be the battery vendor's model number while "361-00097-00" is Garmin's number. This number is also printed on the battery but not labeled.
• I tried using the QR codes printed on both sides of the original battery. These appeared to be dead-ends, as they both led to a phone number (??). Later, I went back and reviewed the phone number carefully. It was: (361) 0009-700. See what happened? The QR code app found the number of digits that matched a US phone number, so assumed that's what it was and formatted it that way, but in fact this just Garmin's part number, which happens to match the same number of digits as a phone number! 361-00097-00. Once I realized that, this was another clue that this part number was the important one.
• Based on searching for ASDB402334-P1 I ended up quickly buying a battery off of shop-battery.com (Perfect site name!). A week later, I had still not gotten a tracking number, and two messages to their email address had gone unanswered. Cannot recommend! They don't say were they are located, but I suspect they are located in China. Living in the US, that was going to be a long wait even if they did get back to me. Eventually, the battery did arrive, but didn't boot when connected or after charging the watch.