Battery drain issue in not-ideal conditions (?)

Hi,

I would like to ask more experienced inReach users how they manage the battery life of their devices.

I got my inReach last Friday and went on 2 nights/days hike, sleeping outdoor with no indoor time at all. I have paired the device with iPhone X and Fenix 5+ and set it to log every 5 minutes & send location every hour. I have started tracking at 8pm. To my surprise, the battery was half empty the next day morning, after less than 12 hours.

I was blaming Bluetooth and/or ANT+ for the fact, mostly because I could not explain the battery drain otherwise and because I noticed that the Fenix watch battery was half-empty, too (no activity started). So, I have switched off both radios and hoped it will do better for the remaining part of my trip.

But the battery fell under 25% the same day evening, so the quarter of the battery was drained during the period of about 12 hours. I stopped the tracking. I tried to send a message. It took ages under trees. The next day morning, after around 8 hours, the battery fell under 10%.

I was very disappointed and thought I probably have a faulty unit, and I need to get it replaced / serviced. Before doing so, I wanted to do more tests, which I did:

I have charged the device fully, and let it powered on without tracking and touching it, next to a large window in my house. To my understanding, in this mode it should only check for new messages every hour. The battery drain was very fast (I don't have the exact figures here with me, but it was either 25 or 50% in either 24 or 30 hours) - much worse than the figures claimed by Garmin.

Then, I have charged the device again and went for an MTB ride. I have set the device to log every second and send location every 10 minutes, to drain the device as fast as I can. To my surprise, the battery was at 87% after 4 hours and a bit. So, in this mode and conditions, the battery would keep the device alive for 30 hours, exactly matching Garmin claims.

So here I am with very inconsistent results. The first hike where the battery fell short by far was mostly in forest with a lot of trees, often in quite narrow valleys. The MTB ride where the battery did well was in better conditions, but still with a part of it in deep forest. The tracking points were sent precisely every 10 minutes with no delays.

My current theory is that what drains the battery most is when the device is trying to send a tracking point or send/check for messages but is unable to do so because it cannot find the satellite, or the connection is very bad. And if that happens, it can suck the battery completely within few hours.

I have bought the device because I plan a 14-days long trip to place with no electricity, no cellular coverage, very little population and some (tiny) chance of being kidnapped by pirates or other armed extremist group operating in the area. I wanted to be able to leave a track of where I am to my family, and let my last location be available to a rescue services in case it is needed.

But I have no idea how to set the device to serve this purpose. If I keep it switched off and only send my location manually when having perfect view of the sky, I should be able to keep the device charged for the duration of a trip. But in such mode my last location logged may be easily 100 kms away. If I use the "extended tracking" mode and log every hour, I risk that the device will try to send a location under bad conditions, for example under heavy trees in a jungle, and it will drain the battery fast.

I would love Garmin to tweak the communication logic in a way it would stop trying to send a track point after some time in very bad conditions and instead retry again a little bit later. If this is done well (and technically achievable), it would solve my problem.

So, my question is: what are your experiences so far and how do you use the device when you need it to work for an extended period?

Thanks,
David

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0 twolpert over 6 years ago

The significant thing in our description of fast drain is not the tree cover, although that contributes (especially if the foliage is wet). It's "often in quite narrow valleys". The Iridium constellation is such that this kind of topography makes it very difficult to "catch" a satellite in view. So yes, retries on data transmissions are going to eat the battery.

I have not tested the Mini. Older iR devices do back off on the retries after a period of failure. However, they will continue to retry until the traffic is sent. If challenging conditions persist, the retries will continue to consume battery.

This is a safety device. It's very difficult to balance reliable data transmission with battery life. A device with a fully charged battery does you no good if it never transmits your position because conditions are challenging.

In my experience, the battery meter on the Mini is somewhat non-linear. In consistent conditions, the final 25% of the charge is consumed much more quickly than the first 25%. Keep this in mind during field use.

Personally, I would not depend on a Mini for a 14-day trip with no possibility of recharging in the field. I'd either carry an external battery pack or (conditions permitting) a solar charger. In fact, for extended trips like this, you'd probably have been better off with one of the larger iR devices (with larger batteries) and field charging equipment.

There's a lot of uncertainty in your final figures. 25% in 30 hours would be good. 50% in 24 hours might be tolerable, but not good. This makes it hard to tell what you're actually getting. But in general, it does not appear to me that what you are seeing is unusual. Remember that Garmin's claims are always "up to" some time interval. And they are always liberally hedged with YMMV. Those figures are best treated as the absolute best possible outcome. Your actual results will always be worse.

Windowsill battery tests are not reliable. They generally show less battery drain than field conditions, but there are a lot of variables.

You are on the right track with disabling all possible radios. Your best battery life will be with extended tracking, which does that among other things. Also, keep the unit as exposed as possible - for example on the top of a shoulder strap. If possible, stop for a while whenever you have a good view of the sky to allow the unit to send whatever data it has backed up.

Unfortunately, it's difficult to tell for sure that the mini has traffic waiting. If it is actively trying to send, you will see the curved up-arrow on the status line on the home screen. But if it's between retries, the only way to tell AFAIK is to start the power-down sequence. You will be warned if points are pending.

Finally, note that all iR devices adjust the tracking interval when the unit is stationary. Regardless of your settings, it will send a track point only once every 4 hours. However, the device does wake up periodically to take a position fix. This is how it determines whether or not the device is again in motion. Mentioning this only because it helps give a more complete picture of battery usage.

0 WD over 6 years ago

One of the videos under the MINI sales or support site list a graph with battery time, with respect to different config settings. However, I have found it not to be entirely accurate. The MINI seems to drain much faster than the chart details. Also, I don't think it lists if ANT or BT is in use. I feel my usage has been similar to yours, if that helps any.

0 sousekd over 6 years ago

Hi twolpert,

Thank you for a long post and valuable insights, really appreciated.

The significant thing in our description of fast drain is not the tree cover, although that contributes (especially if the foliage is wet). It's "often in quite narrow valleys".

That would explain why it was so much better during my MTB ride. The place I am preparing for is quite flat, but there is a jungle around the roads... hard to guess how it will behave.

This is a safety device. It's very difficult to balance reliable data transmission with battery life. A device with a fully charged battery does you no good if it never transmits your position because conditions are challenging.

Yeah you are right. If it does not log when you are stationery, it only needs to go through the "challenging conditions communication exchange" once (per 4 hours) during a night. If it is tweaked to do not try so hard and cancel a communication attempt sooner, it may not send your position after an accident... And I understand that it makes sense to try hard when you move - there is a chance to catch a satellite due to changing conditions...

I think the mini would work perfectly well for shorter, one-day trips, where you generally do not care about battery. But my first example shows that in the unfortunate conditions, it may be unable to survive 2-3 days long trip, even if set-up well.

I need to test how the "extended tracking" feature behaves when set-up to send position once per hour or two. Maybe it has some more optimizations than what is publicly documented, like tweaked time-out values etc. And maybe the best trick I should learn is to switch the device off when not moving - I haven't tried that on my first trip :-)).

I will update the post with with further test results, as soon as I will be able to go out again.

Thanks again,
David

0 sousekd over 6 years ago

The MINI seems to drain much faster than the chart details.

Was that this chart?
https://support.garmin.com/en-US/?faq=xzbn1lrET79h65EgOUEHj9

I would be perfectly happy if I can get half of the claimed 2000 hours with 2-hours send interval in extended tracking :-)

0 twolpert over 6 years ago

Chart does not include ANT+ connection to a wearable. I assume this is also disabled in extended tracking mode, but I don't know for sure. BT is covered by the "paired with phone" column.

0 WD over 6 years ago

Was that this chart?
https://support.garmin.com/en-US/?fa...T79h65EgOUEHj9

I would be perfectly happy if I can get half of the claimed 2000 hours with 2-hours send interval in extended tracking :-)

The chart I saw was actually in a video for MINI use. But the numbers look similar. I do think twolpert is correct that ANT is probably not calculated in. But then my question would be "what is the battery drain of ANT, as compared to BT?". Either way, I'll probably test some of these myself just to see, but so far, I can't achieve 35 hours with any connected devices. Maybe 24 at most.

0 Dogbert62 over 6 years ago

All,

I am in the same boat...

Firmware 2.3
Display backlighting -off
Send interval -off
Log interval -off
Auto track -off
Extended tracking -on
Bluetooth status -off
Ant+ status -off
Ring until read -off

72% battery left after 13.5hrs. I checked it in the first few hours (my guess before it pinged for messages) and it seemed to be running about 1% per hour.. So, my guess is that the device had trouble connecting to the satellite sitting the window sill. Regardless, 1%/hr is 4 days which is nowhere near the numbers presented in the chart.

I plan to use this in the extended tracking mode with a manual, twice daily, "checking in" with wife. So, I am hoping I am missing something, or there will be a FW update , to increase the life in extended tracking.

I will recharge the mini and place it outside in open sky to better mimic my use case but I doubt I will see much improvement over 1%/hr

Regardless, this is a really cool device..

0 sousekd over 6 years ago

72% battery left after 13.5hrs.

Yeah, it depends on conditions / visibility of the sky. During my last test, my device went from 100% to 67% in 16-18 hours, which means drain around or just little under 2% per hour with no use at all, just automatic checking for messages. It nicely match with your findings. It was indoor, next to a window, in my house. I plan to measure it in my office where we have large rooftop widnows, and I am positive I'll get a bit better results there.

As I understand, a device sitting idle with no logging / tracking enabled and Bluetooth / ANT+ turned off shouldn't drain battery much faster than "extended tracking with 1-hour send interval", which should last up-to 1075 hours. Theoretically, extended tracking mode can conserve more power by powering off some components between the cycles, but I don't think the device does so much more processing in the idle mode (tracking off) to drain 20-times more power.

...but when you look at the table here, the device should last twice as long in the extended tracking mode (185 hrs) in comparison with standard use (90 hrs, with 10-min send interval), so maybe there is more to it than we realize. I will test the extended mode this week and will report back.

0 AllanOlesen67 over 6 years ago

Your battery is 1250 mAh, and the device can charge from USB, right? So you should be able to get approx. 10-12 charges from a good quality 16 Ah power bank. I have one of those, and it weighs around 330 gram. Could that be a solution?

0 sousekd over 6 years ago

Of course it is a viable solution, but there may be more devices you need to charge during a longer trip, and you want to minimize the amount of battery packs needed.

The point is that the battery life should be at least close or comparable to what Garmin claims. Having it 20-times shorter can only mean we use the device in a different way or settings than needed, or that it is very variable and really depends on conditions, or the devices needs to be serviced or replaced. I would like to understand what is going on to find the best possible usage pattern in order to allow it to work on 14-days long trip. If that means "always switch it off when indoors" or "only switch it on when extended mode is enabled to avoid battery drain during the idle mode", it is something I can work with...