Replace battery for Forruner 945 ?

A common benchmark of rechargeable batteries is that they lose about 20% of capacity over about 500 charge cycles. For a device like a smartphone with a daily charge cycle, it may reach 500 charge cycles in about 18 months, or 1000 charge cycles in the 3 year timeframe you mention, and battery life can be seriously degraded at this point.

However, the F945 has a pretty massive battery life, and even those exercising 7-10 hours per week are typically reporting a charge cycle of about 1 week. So it's going to take 10 years to reach the 500 charge cycle benchmark.

Balanced against this, is that fact that as an outdoor sports watch, the F945 is potentially operated in harsh environments (eg. salt water while swimming, mud in trail runs, etc), and water and dust-proofing is important. Breaking the seals to replace the battery risks compromising the waterproofing. For this reason, it is not intended that the battery of the F945 be replaced.

Currently, I use F945 (starting from September 2019) with a frequency of 1.5-2h/day for cycling with connection to external sensors. Key settings: heart rate, SPO2, step count....all day. Do not receive SMS, phone calls, listen to music. Currently, each time 100% fully charged, it only takes about more than 50 hours, only about 14%. So the battery has been degraded fast?

SPO2 is a huge power drain. Turn that off an see what you get.

Mine isn't holding a charge longer than 2 days, either.  I'd love to know a fix.

mcalista said:

SPO2 is a huge power drain. Turn that off an see what you get.

I turned off all-day measurement with heart rate and SPO2. Sleep measurement mode only. But 2 days now, check those parameters when sleeping again nothing?

What the manufacturer states and what you get are two different things and trust me there isn't a hope in hell the battery will hold out 10 years (with decent life), no matter how infrequently you charge it.

If Garmin are confident of this, why are they not offering a 10 year warranty on the battery?

I am replacing a Polar MS watch as the battery only holds about 2 hrs charge and it is only 3 years old. I was considering a Garmin 945, but if the battery is not replaceable I will look elsewhere. This is just another case of built in obsolescence. Disposable society. 

I know many people like to have/buy the latest so doesn't effect them as they just replace every year or so. But for me, I am not that financially well off so always consider what is the best value for my limited money. 

Any chance you got this sorted?
I have an aging (also almost 3YO, at 33MO currently) 945, that seems to have really taken a nose-dive in this regard, the past few weeks (same exact set of customizations and widgets, no interface changes for some months now, at least), even just overnight is nuking the battery (used to drain 2-4% overnight, now it's on a 10-15% rate). 

I've checked everything, WiFi is disabled, PulseOx is disabled, I only enabled Bluetooth to sync, or to connect to an external HR source, or (cycling) trainer. 

Support asked me the same myriad of questions, and concluded that I seem to have an issue, but said they didn't have a battery-replacement option, at this time (not clear to me if they ever have?).  They offered me a deal, on a refurb, but at this point I'm just trying to make it to a 955 or maybe the Fenix 7 Solar (already sold out, where I was saving my gift-cards for), so I don't really want to invest in a "maybe okay" refurbished model.  We had a TERRIBLE experience with a VA4S refurb (official) where it wouldn't even make it a day, on the 2nd charge, so I'm very refurb-unfriendly at this point, for Garmin anyway (I had a long chat w/support on that one, too, and they basically recommended I return and get a brand-new VA4S, which is what we did, and it functions fine, in the 6 months since).

How in the heck can there be no way to repair an 800-dolllar watch, you're just out-of-luck, really???

This is a pretty bum deal, in the new world of supply-chain headaches, IMHO.

I have a similar issue, but it is very hard to tell whether the battery degraded or the general power consumption rose with the newer firmwares.

A comparison with my FR935 is interesting, currently the FR945 lasts for about one week with very little activities. The FR935 with one daily run for about 1h still lasts 3 weeks despite being 5 years old.

Interesting, because the FR935's Mediatek GPS chipset is said to be more power consuming than the Sony chipset in the FR945.

But maybe it's really a poor quality battery that has been used in the FR945 and degraded much quicker than in previous models.

HUMODDA said:

The FR935 with one daily run for about 1h still lasts 3 weeks despite being 5 years old.

That is amazing.

My 945 used to last 4 days on a charge with my 8-10 hours a week of GPS usage, now it's down to about 3 days.  I continue to be disappointed and underwhelmed by my 945 battery life compared to reported specs.