So, almost every thread you see on here where people talk about using a cell phone vs Garmin/GPS, the idea that a phone battery won't last long enough is brought up because "GPS sucks battery". In my experience with iPhones (can't talk Android sorry), this is a complete myth. Let me tell you about my setup. I have an iPhone 6 (held in left/back jersey pocket), I use the Cyclemeter App. On my bike I have a Wahoo BlueSC v2.0 speed/cadence meter, and a Wahoo RFLKT (so I can see my speed/cadence/HR/distance without having to view the phone screen). I also have a Wahoo BlueHR heartrate strap.

When I ride, I turn off "mobile data", this means that the phone does not access the internet in the background while I ride.

Using this set up I find that my phone drains at a rate of about 10% an hour.

Case in point, on Saturday I did a century ride, and also rode 6 miles to and from the event start point from my house. I started on 100% charge. At the end of the ride, after 8h30m of elapse time (7 hours spent riding), my iPhone's battery was at 35% capacity.

As for the "I need my phone for emergency calls" issue. I carried a small battery pack that could recharge my phone fully, but I didn't need it and still could have made calls if necessary.

There are many reasons to use a Garmin instead of a phone, but in my experience, battery life simply isn't one of them.

I use my phone to stream Pandora on solo rides, so multi-tasking it to Strava or other GPS-related duties seems unwise. I leave that to my Garmin 500, which uses about 8% of it's battery on a 3-hour ride.

Friend bought a new battery for the phone he has ..

Apps like MayMyRide and Strava usually are the drain on the phone battery. I had several issues with both apps, MMR draining my battery far faster than normal, almost a rate of 20% an hour for some reason, and Strava not recording my rides. Currently waiting on my Garmin EDGE 810 to show up any day here so I can start using that. This will replace a Cateye Stealth 10 that I absolutely despise.

My Samsung S5 will go from 7am to 11pm and still usually have around 30-40% left on it at bed time.

I leave everything on all the time; GPS, Wifi, 4G, BT.

I don't let it capture ride data from my Garmin until after a ride though, I then turn the Garmin BT on, let it sync and then turn Garmin BT back off.

I think most of that worry comes from attempting to use the phone as the display also rather than just as a gps recording the ride.

I charge my phone once a day. I charge my Garmin once a week.

So then you should be fine with a phone.

J.

I actually see this as a plus for using a phone. My phone is always adequately charged for a regular ride, but something I have to take off my bike to charge once a week is more likely to run out of batteries at an inconvenient time.

Well, you're attacking a straw man a bit here...the argument generally is that using the phone as a mounted bike computer drains battery excessively fast, not that using your phone to track your ride drains battery.

Also, I'm not sure why there is a need to "debunk" the "myths" about the benefits of using a standalone bike computer...I don't think anyone is saying they're necessary, but simply that they have certain advantages (and yes, battery is one, since my Garmin with display on would have about 50% of its battery left after the ride you mention, and my phone would be almost 100%, without needing to carry around a separate battery and cable) over phones, and some disadvantages as well. But hey, if you don't want/need one, then don't buy one, and feel free to tell others why you made that choice. We're not talking about vaccines here....

I agree that using the phone as a screen severely affects battery life, but I've had people argue that even in the back pocket, a phone fails due to battery life.

That certainly used to be the case a couple of years ago. I remember when MapMyRide would kill my iPhone4 battery in like two hours. Today however, the drain is relatively minimal if you're just tracking (with Strava at least...I stopped using MMR a long time ago).

I'm fine with a phone. Very useful tool. Use it for sending texts, looking up traffic, etc. Occasionally it's useful for making a phone call.

Mine still has a full battery when I need it because I use a bike computer for my bike.

Sure. My experience is the opposite, though. My Garmin usually has enough juice in the battery to go for a ride because its battery lasts a long time. And my phone probably doesn't because its battery doesn't last all that long.

(I'm exaggerating a little bit. The phone usually has enough at the end of the day to probably get through an evening ride.)

For me it's the "one more thing to charge" issue. My phone is always adequately charged, even if I ride in the evening (which I'll admit I only do once a week, most of my rides are lunchtime or late afternoon).

Every phone is different, everyone's use is different, I understand that. My point here is that I've regularly been told that with my setup, I'll be "OK, except for long rides". 113 miles I did on Saturday is the longest single ride I've ever done, and I did it on one charge, and I still had juice to make phone calls and use my phone for the rest of the day afterwards.

Using your criteria, of course.

Personally, I prefer Root Beer to Coke. It would never ocur to me to write a post about how silly it is for people to drink coke when they could be drinking Root Beer.

But since you brought it up, battery life is a major reason I prefer my 510 to my iPhone for a bike computer. While I see your point, I don't always start a ride with my phone at 100%. There isn't always a charge available at the end of a ride. Sometimes I stop for lunch and want to use my phone to email/facebook/makecalls/generally burn battery life. I like to use my phone for a camera. Etc, etc., etc.

Also, if my Garmin runs out of power mid ride, I'm annoyed, but I'm not in danger or seriously inconvenienced. If my phone goes out on me mid ride, I could conceivably be stranded or worse.

So I prefer the 510.

FWIW, it also has more configurable screens for monitoring data, uploads directly to Garmin/Strava/Training Peaks/RWGPR/MMR, is rain proof, is less attractive to theives, and costs roughly 1/2 of what my last replacement phone cost. It's apso covered by Garmin's post-waranty replacement policy - I can replace it for around $80 if I mess it up (My last one got run over after it fell off during a race - $80 and a few days and I had a reconditioned 510).

Put me in the Bike computer beats iPhone by a mile category.

Err... OK? I was specifically targeting the "battery life" issue. My last sentence was specifically to avoid making this thread about "Garmin vs smartphone", which I have little interest in debating, as I see pros and cons on both sides.

Yeah, this is never an issue for me. Horses for courses I guess. I don't set out on a ride with 20% on my phone as a rule, and 10% drainage per hour means I don't get near full battery drain unless I ride for a long time. Typical rides for me are 1-3 hours. It's never an issue.
My answer to this is that if your phone is such a life-and-death thing, invest in a small and cheap portable battery charger for emergencies. I've had my phone die in my pocket when I thought I wasn't using it because some app decided to go into a death spiral and drain the battery. If your phone is your lifeline, then a backup battery should be part of that. They don't weigh that much. They are cheap. Check Monoprice or Amazon.

Again, that is not what this thread is about at all.

Back to the original statement about extending battery life by turning off mobile data. That's very good battery life, no question there. The battery sucking culprit must be the cellular data function, not the GPS receiver. Android phones have always been able to use GPS in airplane mode to extend battery life. Beginning with iOS 8.3, iPhones also have this feature. With both operating systems, airplane mode now leaves GPS on, and provides the option to turn on WIFI and/or Bluetooth.

I put a new battery in my bike comp about once every 2 years.

Do you charge your phone before every ride? I'm a little confused.

I charge my phone overnight. Mornings are when it's most full, and it'll run down over the course of the day. By the time I get home from work (when I start looking to take my bike out most days) I've already been running it down for 9 to 10 hours. For me, I'd either start riding with 50 % phone power, or have to go home and wait to exercise until the battery says I can go. Do you charge yours many times throughout the day? I'm guessing you don't based on your "one more thing to charge" comment.

(I charged my Garmin Friday so it's got plenty of juice left for my next several rides.)

No, but by the time I ride my phone is rarely below 50% charge. I charge it overnight.

No I don't usually have to charge it during the day. Also as I stated above, as I get about 10% battery drain per hour, starting a ride with a phone at 50% charge would not be an issue for me unless I was planning to ride >3 hours. I don't usually do this on a normal work day.

That's interesting. I'll have to try it in airplane mode on a future ride to see if it extends the battery life any further than just having data turned off.

I used to argue for my phone... until I got a Garmin

Now I wish I would have bought it sooner.

Again, I'm not really arguing "Garmin vs Phone" here. Garmins are great, and I'm sure I'd enjoy owning one, but for now I'm saving my money for other things like a new set of wheels. My issue is with the narrative that I see on here and in my real world contact with cyclists that GPS functionality on phones sucks the battery, making them useless as bike computers.

I don't want to argue with my brother in steel here but if the iPhone was doing everything my Garmin was doing (or can do) it would likely run down pretty quickly.

But yes, for base functions and displays, I can see how a phone plus some of the other parts you have to buy would to get the similar base functionality, would be a nice alternative to spending bucks on a Edge 1000 for example.