I have worn a smartwatch on every run, ride, and race since 2019, and I keep a spreadsheet of the ones that lie about their metrics. So when a list puts budget smartwatches and battery replacements side by side, I do not start with the spec sheet. I start with one question: are you trying to get a watch onto your wrist, or keep one that is already there?
That question matters because both halves of this comparison fail in the same way. A cheap watch that counts your steps but guesses your heart rate is not a training tool, it is a notification machine. A replacement cell that does not match your exact model number is not a repair, it is a dead part in a padded envelope. Either way, the money is small and the cost of getting it wrong is your trust in the numbers.
Related: How to Check Smartwatch Battery Health Before You Buy
If you want a watch, the Smart Watch for Women Men with call answering and two bands in the box is the pick, because it is the only product in this comparison that tells time on day one. If you already own a Garmin Fenix 5S or 5X and the battery is fading, one of the two replacement cells is the smarter spend. Those are the two real answers here. Everything below is why.
Smart Watch for Women Men, Answer/Make Call, 1.83"HD Touchscreen, 2 Bands, IP67 Waterproof Fitness Tracker, Heart Rate/Sleep Monitor, DIY Dial, Multi-Sport Modes Pedometer, Smartwatch for iOS/Android
The only product here that works as a watch out of the box, and the only one with a spare strap in the box. Call answering and IP67 water resistance cover the daily basics.
No GPS listed, and wrist heart rate at this level is a guess during intervals rather than a measurement.
Smart Watch for Men, 1000 mAh Battery, 1.85" HD Fitness Tracker, Heart Rate Sleep Monitor, 120+ Sport Modes, IP68 Waterproof, Smartwatch for iOS Android
Leads with a 1000 mAh battery and 120+ sport modes, and IP68 is the higher of the two water ratings in this list.
No GPS listed. A big battery number is the spec I trust last, and a sport mode count says nothing about accuracy.
Pattaya 361-00096-00 Battery Replacement for Garmi n Feni x 5s Feni x 5S Plus Smart Watch
A way to keep an older Fenix 5S or 5S Plus running instead of replacing the whole watch.
It is a battery, not a watch. The wrong model number means a dead part and a wasted order.
Pattaya 361-00098-00 Battery Replacement for Garmi n Feni x 5X Feni x 5X Running Smartwatch Watch
The same logic for the larger Fenix 5X and the running variants named in the listing.
Fits the 5X family only. The smaller 5S takes a different cell, and ordering from memory is how people end up with the wrong part.
Prices and availability were captured from Amazon Creators API and may change.
These four products are not the same kind of thing
Two of them are watches. Two of them are parts. Comparing a cheap watch to a replacement battery is like comparing a bicycle to a set of tires: they belong to the same hobby and they solve completely different problems.
I am not being pedantic. The mistake I see most often in this category is someone buying a battery for a watch they do not own, or buying an inexpensive watch expecting it to replace a Garmin. Both are avoidable with five minutes of reading.
The two inexpensive watches
The Smart Watch for Women Men lists a 1.83 inch HD touchscreen, call answering and dialing, IP67 water resistance, heart rate and sleep monitoring, a DIY dial, multi sport modes, a pedometer, and two bands in the box. It works with iOS and Android. Visit on Amazon →
The Smart Watch for Men lists a 1.85 inch HD display, a 1000 mAh battery, 120 plus sport modes, IP68 water resistance, heart rate and sleep monitoring, and the same iOS and Android support. Visit on Amazon →
Those spec sheets describe two devices from the same shelf, and the differences that matter to me are narrower than the marketing suggests:
- IP68 is the more protective of the two water ratings. IP67 survives splashes and brief immersion, IP68 is rated for longer or deeper exposure. Neither is a dive rating, and neither belongs in a pool for an hour.
- The 1000 mAh battery is the headline number on the second watch, and it is also the number I would verify last. Big battery claims are the easiest thing on a spec sheet to write and the hardest to audit.
- The two band bundle on the first watch is a real, if unglamorous, advantage. Straps wear out before watches do.
What neither listing includes is GPS. Read those names again and you will not find it. For a runner, that is the whole ballgame. A watch without GPS can estimate distance from arm swing and stride length, and that estimate drifts the moment your stride changes on a hill. I have tested that failure mode on other watches and it is not subtle. If your training depends on pace, a watch without GPS is not a training watch.
Heart rate is the second problem. Optical wrist sensors at this level are the hardest engineering problem in the category, and the cheap ones handle it the way you would expect: fine at rest, unreliable during intervals, prone to locking onto your cadence instead of your pulse. I do not have a chest strap session logged against either of these two watches, so I am not going to pretend I know how their sensors behave. What I can tell you is the pattern I have measured across the budget tier, and it is consistent enough that I would not build a training plan on it.
The two replacement batteries
The 361-00096-00 is a replacement battery for the Fenix 5S and 5S Plus. Visit on Amazon →
The 361-00098-00 is a replacement battery for the Fenix 5X and the 5X running models. Visit on Amazon →
Both are listed as replacements, which means they exist for one reason: the original cell in a five or six year old watch has lost capacity while the watch itself is still perfectly good.
This is the most underrated purchase in wearables. A Fenix that still holds a GPS fix and still matches a chest strap is worth keeping, and the alternative is buying a new watch at many times the cost of a cell. If you are the kind of person who keeps gear for a decade, this is your upgrade path.
Two honest caveats. First, these are cells, not watches, so there is nothing to review until someone installs one. Second, opening a sealed watch case is not a beginner repair. If you are not comfortable with small screws, gaskets, and a proper seal when you close it back up, budget for a shop to do the work. A watch that loses its water resistance after a home repair is a worse outcome than a tired battery.
The compatibility trap
This is where people actually lose money.
The 5S cell and the 5X cell are different parts for different watches. The 5S and 5S Plus use one, the 5X and its running variants use the other. They are not interchangeable, and buying the wrong one is a completely avoidable mistake.
So before you order: find your exact model on the back of the case, and match the part number in the product name to it. If your watch says 5X, the 361-00098-00 is your part. If it says 5S or 5S Plus, you want the 361-00096-00. Ten seconds of reading beats a return.
The trade-offs, stated plainly
- If you want a watch today and you do not run with GPS: the Smart Watch for Women Men gives you the most complete package, including a second strap.
- If battery anxiety is your main complaint and GPS is not: the Smart Watch for Men leads with a 1000 mAh cell, and you should treat that as a claim until you have lived with it.
- If you already own a Fenix 5S or 5S Plus: the 361-00096-00 is the least wasteful way back to a full week of use, provided the rest of the watch is healthy.
- If you already own a Fenix 5X: the 361-00098-00 is the equivalent move, and the model match is not optional.
- If you want accurate pace and heart rate data: none of these four is the answer. That purchase starts with GPS in the spec list and a chest strap on your test bench.
How I would decide
Start with what is already on your wrist or in your drawer.
If you own nothing and you want notifications, step counts, sleep estimates, and calls on your wrist, the call answering watch with two bands is the one I would try. It does the most out of the box.
If you own a Fenix and the battery is the only problem, buy the cell that matches your case. Do not buy a new inexpensive watch to replace a Garmin that still tracks accurately. You would be trading a tool for a toy.
If you own a Fenix and the GPS or the heart rate sensor has also started drifting, the battery is not your problem, and a replacement cell will not fix it. That is when a new watch makes sense.
What I am testing next
I am in the middle of a 2026 running watch test: four units, a certified course for GPS accuracy, and a chest strap comparison on every run. I do not publish a GPS or heart rate verdict on any watch until it has at least ten runs against that strap, and I do not publish battery life at "light use," because that number is a marketing department's fiction.
None of the four products in this comparison is in that test. Two of them do not claim GPS, and the other two are batteries. That is not a knock. It just means the right reason to buy them is not the reason most people buy them.
Bottom line
The budget smartwatch and battery replacement question comes down to which problem you have. If you need a watch, buy the one that works as a watch and expect a fitness tracker, not a coach. If you need to keep a good watch alive, buy the exact cell for your model, and pay someone to install it if you are not confident doing it yourself.
And if you are chasing accurate pace and heart rate, save your money. The watch that tells you the truth about your training costs more than any of these four, and the difference shows up in the GPS trace, not the spec sheet.