Edge 130 Plus elevation accuracy is poor following switch off and on in mid ride.

On some rides, after 2 to 4 hours, I have definitely seen that the device is getting tired and averages out elevation over miles or minutes, or something. While at the start, elevation changes seem rather quick and accurate to me: climb a ramp and in a second or two the meters start counting up. I've been wondering why but not much and never made a link to powering down (or just pausing?) during a break. As far as I checked, what it is (not) showing during the ride is the same as what it is (not) recording.

Looking at my elevation graphs, I see nothing as dramatic as your report, but definitely traces of this flattening out on some rides (1 in 10, at least). But I live in a quite flat area and almost all my rides end at home, so the only bumps not recorded at the end are bridges or tunnels. On tours over hills, 10m elevation changes still seem to show up. Just not always if you cross a canal going up and down a 10m high bridge.

On connect's elevation graph of a hilly ride, the elevation is silky smooth for the first 2 hours (I can zoom in down to perfectly reasonable looking 0.1 meter steps), then after a pause (don't know if I also powered down), it turns choppy with increments up to 15m. Meaning that the elevation stays the same for many GPS points whole latitude and longitude still varies accurately, then changes in increments or decrements of up to 15m  in intervals of 12 seconds, followed by plateaus of a multiple of 12 seconds. When the recorded temperature changes, it is always on those 12 second intervals, from the beginning of the recording  (on closer inspection, that was a twisted representation by connect's web interface, not part of the data - it's every 60 seconds indeed).

I did wonder if the Edge gets tired, but I doubt it's saving power because the battery rarely end up below 50%. Also wondered about IQ apps. I only have the temperature one and removing that temperature field didn't help, but I'll try removing the app altogether.

Investigating further:

I did a 45km ride at the weekend with 360m of climb.  The Edge130Plus announced total climb as 146m, so only 40% of the actual.

I stopped it twice during the ride, and following the first stop its elevation recording became poor - often no gradient showing on steep hills.

I have analysed the data a bit more and find that the Edge130Plus updates elevation after a stop only every 60 secs instead of every sec.    And it is EXACTLY 60 seconds..  Its location data is pretty accurate; it records this every second. 

After the first stop the elevation changed every second for 52 secs until 07:36:28:, then after that it changed at

07:37:28

07:38:28

07:40:28 ( a 2-minute gap - perhaps the two heights were actually the same)

until 

08:38:28.  It only every changed elevation on the 28th sec of each minute.

After the second stop I re-started at 09:07.  A quick flurry of elevation corrections, (it was 20m out), until 09:07:52.  Then the next changes came at

09:08:52

09:09:52

09:10:52

etc.  

The updating period remains constant throughout the ride (a few are missed, presumably because it thinks that the new elevation is the same as the existing one, but the elevation error becomes bigger and bigger; the lag seems to build up.  For example in this 30 minute section there are some significant climbs which it either under-states or, in the case of the sharp down-and up at the end, misses the descent and climb completely.

I've passed the information to Garmin.  If anyone wants to compare the plots I'm happy to share the tracks on Garmin connect.

Garmin have sent me a second replacement Edge 130Plus.  All three have this problem, namely following a switch-off and on mid-ride the altitude updates every 60 secs (exactly).  They have told me that there is a work-around, namely to allow the unit to auto-switch-off.  I tried it and they are wrong; the problem remains.  Here's a graph I did of a ride yesterday.  

Garmin has told me that they are not going to fix this problem.  So maybe a few of you need to lobby them.

Does the problem occur if it is not turned off and left to go into auto pause?

I don't use auto pause, but I do manually pause. As far as I checked, when the pause duration is shorter than the auto power down time, I didn't see the height problem.

To me, the conclusion is: don't ever power down during an outing, and disable auto power off. Or if you must, record two separate rides. Because:

• Powering down during a ride is made unnecessarily difficult: other (non-Garmin) devices just let you them turn off and resume when you turn them on again. The Edge, inspired by HAL, refuses unless you press other buttons to pause first. Then when you wake it up, it tries to fool you into riding without recording.
• It forgets the destination if you were using find back, or probably any kind of straight line routing.
• And now we know it messes up height recording.

Yep, mine does this.  Can reproduce it consistently by stopping or powering down mid ride. When the ride resumes elevation goes into this suuuper slow sampling/reporting mode for the remainder.

Mine does exactly the same. This is why I disabled auto power-off and on long rides with stops I don't switch it off, I just pause it.

It does so 100 % of the time. Of course I can correct elevation at the end, but current gradient display does not work.

So I am sure this is not a single unit issue, but rather general software problem.

I should have read this forum before buying this unit. I had the 520+ that worked fine but was stolen, I opted for the 130+ because size and simplicity. What I really don't like that they told you that they are not going to fix it.

I asked Garmin to replace the 130plus with a 130 and give me some compensation, or a letter to the retailer explaining that the units are faulty.   They refused, but did offer an Edge 530, which I accepted.  I tried it, but preferred the simplicity of the 130.  So I ebayed the 530 and bought a second hand 130 of eBay. No ended up a net £50 up. They should offer everyone who is dissatisfied with the 130plus something similar.