Just did a 12:57 IM and my 920xt had 20% left at the end. HR and power meter on the bike. Took off the HR strap for the run--I mean jog and walk.

How do you (if I understand you, correctly) turn on the HRM at the start of the bike? The way I read the above....you had the timer on at race start......but only turned on the HRM at the start of the bike?

That would be ideal, for me, although I think my 920 would make 13 hours, pretty easily. I use my 520 for the PM head unit.

Thanks!

My 920xt died at km 29.5 IMMT (around 9hrs 30m) after a full charge. I had it set to give me power and nutrition alerts on the bike which probably also drained the battery but I use an old edge 500 bike computer so that was my only option. In retrospect I should have also turned off bluetooth and wifi, and the backlight. The edge 500 was still going strong when I went to pick up my bike at 9pm LOL.

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Set back light to manual so it never turns on even for 1 second. If it is not set to manual, light always comes on during every notification or alert, if you have mile alert then it will come on 20 times during 20m run.

GPS no glonas

remove all sensors you do not use, have only those that you will use.

it should easily last 15 hours with 1s recording, if you need more turn on UltraTrac mode, but GPS precision will take hit, it should last 40 hours in that mode.

Turned off bluetooth/wifi and backlight. Had HRM and Cadence sensor. Did *not* enable Ultratrac. Lasted over 14 hours for IM.
I have heard that deleting logs on the watch can also help improve the battery life; I have not verified this but wouldn't hurt anyway.

I didn't take my advice so... You could consider not wearing your watch on the swim if you really are concerned (though from the sounds of it you aren't going to have a problem). The data really useless because of the inaccuracies of the watch in open water swimming.

Deleting the history makes a big difference. I had done all the settings recomendations and was getting terrible battery life in my training sessions and low battery alerts before 10hrs of IM racing. After deleting the history, the battery life improved tremendously.

I did IMTX in 16+ hours and finished with mine having 13% battery left. I turned off bluetooth, wifi, and glonass. About an hour before the end of the race, it went into "power save mode" and stopped any alerts, and the screen went dark, but it was still collecting data, but it got the whole race. You should be fine.

That is the only indicator I get on my 920. I can't imagine I changed any factory settings but maybe. I can look when I get home.

The 920 will last a full Ironman. That said there are some things that need to be done to make sure it does. The 920 has the nasty habit of looking for everything you've paired before even if you are using it at that time. One of the great things about the 920 is you can sync multiple sensors to it for different bikes so you can jump on and go and now mess with profiles etc. However, the 920 will continue to look for the other sensors and this a battery drain. Same thing with Bluetooth and WiFi. If you worried about battery life then strip out all the sensor you aren't going to be using and turn off bluetooth, wifi, glosnass, backlight on, etc. and you shouldn't have any issues. I know of multiple people who have raced 15-16+ hour races with no issues (using power meters and hrms).

That said...17% after a 2 hour run is not normal. Even with all the power sucking features turned (or even paired with a phone the entire time and receiving alerts from a crazy group message) it should have had better life than that. Maybe it was not fully charged? By comparison...I did a 4 hour ride on Saturday with everything turned on paired to phone, a hrm and power meter and had 82% left and that was after the upload to garmin connect (which took 3 tries btw).

Yeah, I agree... 17% for a 2 hr run (nothing paired, no backlight, no GLONASS) is excessive...

Frustrating part is that this is my 2nd 920 that's had battery issues...

Sigh

Yes it will last for a 13hr IM, I have friends that have lasted for their 15hr IM. As for how to maximize battery life this is what I did when I had the problem: http://lmgtfy.com/...ry+Life+Garmin+920xt

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Elisha
"Triathlon doesn't build character. It reveals it."

My recent experience at IMCdA on a rough day and a 12:29 finish is that the 920xt died with less than a half mile to go. This is with the HR strap on and power meter during the bike, 1-sec recording. No alerts or anything like that, other than lap alerts every mile on the run. So be faster than 12:25 to be sure. :-)

Ian

There seems to be quite a lot of variety in these watches. I had no issue last years IMChatt, 10:54 with 1 sec on, connected to my power meter, etc.

Last week at IMCdA I learned my battery on the Quarq died overnight, couldn't find a spare so the 5:36 bike the watch was searching for the pm. Ont he run the HR monitor stopped reading HR but still read cadence. Watch lasted the 10:46, although battery warnings were coming on.

I think long as the watch has been lasting as normal and you turn off sensors you are not needing like BT, footpod, etc that is might be expelling battery juice searching for, then you will be ok for 14 hrs or so. Remember if you are using it int he swim it may be connecting/ disconnecting to GPS and HR monitors which might be draining it faster.

True, I'm using the HRM-Tri now and I wasn't before. Normally I'm a sub-12 finisher and have never had battery issues, but the battery does degrade over time as well, and my 920 is from when they first hit the market, so that could be a factor.

By contrast, I don't think the 735xt would last for even my fastest IMs (low 10) based on the battery life I've experienced with it.

Ian

Hi. Yes, it lasted the race.
As far as I can remember it hadn't started giving low battery warnings when I finished. I've gotten more than an hour even after low battery alarms in training when I hadn't taken any measures to reduce energy consumption so it's probable there was still 1.5hrs+ remaining when I finished the race. My time was disappointingly a few minutes over the 13hrs.

I turned off the backlight, Glonass, Bluetooth and WiFi and used my sensors as normal (HR and bike speed/cadence sensor).
My watch was on maybe 10 minutes before the race start to ensure I had GPS aquired and everything was set up correctly so let's say 13:15 from switch on to race finish. I'm pretty confident there was at least 1.5hrs left in it. So best guess is 14:45 duration would have been feasible.

I was disappointed with my time as I was a few minutes outside 13hrs which was the slowest time I had envisaged. I really think 12.5hrs should have been do-able but as much as I knew what the likely issues would be, I still ran foul of some of them.

The swim is my weakest discipline. That's because I don't really enjoy swim training that much so I aim to do enough to be safe and competent but not necessarily enough to be fast. I do triathlon for fun, so that's a perfectly reasonable approach in my opinion. Due to unexpected work and other circumstances in the final 4 months I did much less than even the low volume of swim training I'd planned. I was quite nervous about the swim. However, it went great. I wasn't fast, but I was comfortable throughout and out of the water a couple of minutes faster than I'd predicted. I felt great after the swim which was a big surprise.

The bike is my strongest discipline, usually.
The bike did not go well. Maybe it was the unaccustomed swim distance. I felt good coming out of the water but perhaps it left me more drained than I thought. On the first 90km loop my HR was not excessive but it felt like very hard work despite a disappointing pace. On the second loop my average speed was down about 1.5km/h and my legs were feeling heavy and unresponsive, excessively so. I was definitely having a bad bike day anyway, but I think I pushed it a bit on the first 100km due to dissatisfaction with the slow pace I was seeing, which made it even worse.

After the bad bike I was about 15-20mins behind schedule starting the run and not feeling great coming out of transition. However, I quickly got into a solid rhythm and was suprised to find my bad cycling legs coming good again for the run. I had always doubted my ability to run the entire 42.2km but as I put distance behind me I started to get more optimistic and actually felt I might gain back the 15-20mins I'd lost on the bike. My plan had always allowed for a slow run pace. I was going strong as I passed 25km but then suddenly I started feeling sharp pain in my sides and arms with every stride. My legs still felt okay but muscles that were doing nothing much started causing me real pain. That was unexpected! I tried to keep running but it was agony. Just beyond 27km I resorted to running a couple of hundred meters in pain and reverting to walking for another couple of hundred and continued miserably like this for several kilometers. Then I realised that I'd taken on no salt since the bike. I was using electrolyte tabs with sufficient salt on the bike, added to the provided water. I had salt capsules in my pocket for the run but had completely forgotten them. I didn't know if this was the cause of my problems or if it was just fatigue but I took a salt capsule and then another 10mins later. Very quickly I started feeling better. The pain faded considerably though I was still a little uncomfortable, and the pain itself had taken a toll and despite the slow pace for the preceeding hour or so, I had very little energy. I started running again from around 35km. I still walked occasionally but only briefly, and when running my pace was respectable. I was feeling better rather than worse from 35km to 40km. Then I decided no more walking and finished the last 2km pretty strongly.

That's my race report!

Anyway, from my experience, the 920XT is probably fine for most people on an IM, providing you take some measures to reduce energy usage compared to how you may use it in training.

Incidentally, I used the Garmin triathlon HR strap for the swim and bike and then switched to a Scoshe Rhythm for the run. I can't see this having any effect on battery life, just including it for completeness.

Battery wears with age - so it depends a bit on how used your watch is :) But it really should hold up NP. The 735 on the other hand - would not.

Yep no problems at all. 16 and 17hr Ironmans with PM.

First world problems....

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Trying since 81
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Turn off gps for swim/bike I only use power and time on bike and time in the swim. Then turn on gps for run for pace

I don't specifically recall now - it was 10.5 months ago. But my bet is I had it on my wrist through the swim and just powered it up while running to/from the change tent. From bike's point of view, nothing unusual, HRM was on when I got there.

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To breathe, to feel, to know I'm alive.

Ummm, but why do an Ironman if you can't put the bike leg on Strava?

Just upgraded to the 920xt from the 305.

I hate charging it thru the computer. With the 305 USB charging cord could be plugged straight into the computer or the gadget that could be plugged into the wall to charge.

I am wondering if anyone charges their 920xt thru this same gadget that the 305 came with straight into the wall.

Does anyone think it could/would cause damage to the 920xt by doing this. Thanks.

did IM Copenhagen two weeks ago, tured off bluetooh and wireless, but had gps, HRM on for everything, had power connected on the bike and had normal sampling on. had 30 or 40% left crossing the line after 10h43. absoltue no problem with a 13hr IM if your battery is decent

I don't see why not, I have only charged my 920xt with a smart USB wall plug, no issues so far about 3 months use.