disable 66i auto power off when unplugged from power?

I am not aware of any way to explicitly control this.

The device powers up unconditionally when connected to power. If it's a computer USB port, it comes up in data transfer mode (removable USB "drive"). If it's a charger, wall wart, or whatever, it comes up in regular mode.

When in data transfer mode, it powers down immediately on "dismount". (I don't know what happens if you just unplug it. I can't quite bring myself to do that.)

When on an external power supply, it DOES prompt to ask what you want to do. You have 30 seconds to respond. If you don't respond, it powers down. There is an audible beep when the countdown starts.

For your use case, you are probably better off NOT attempting to continuously charge the device while hiking. 

If you want to submit an enhancement request, you can do it here:

https://www.garmin.com/en-US/forms/ideas/

I know it gives you 30 seconds to respond when power is disconnected. The problem becomes when you don't know that has happened. Now the device is off and you don't know it missing tracks and possible messages and if something happens and you can't reach the device no one know where you are and they can't get your location. The solution to that is don't charge the device while using it? That is not a helpful or acceptable solution. I do now see this question have been brought up before and mentioned other places as a flaw and reason to avoid the device. It also appears that the inreach mini had the same issue at one point that was fixed in a firmware update. That is really the only acceptable solution to this problem. Implement the option for the end user to choose when the device is powered off and on.

That’s a pretty important safety feature that you want Garmin to give users the ability to disable. 

That’s why it automatically shuts off because it assumes you are completely unaware that you lost corded power and it assumes you were relying on that power instead of battery.  It assumes you’re counting on the battery backup for emergency.  It would be a double whammy if you unknowingly lose main corded power and also unknowingly drain your backup battery power.  That’s exactly why the safety feature exists (because of the "unknowingly" part).  

These devices get used on boats, cars, trucks, ATVs, motorcycles, planes, remote cabins etc where people assume they have main corded power and the internal battery is for backup.

I would also recommend charging the device in your tent at night instead  of while hiking.  Hiking or any activity where you’ve got cables hanging out or can be jostled out is probably not the best practice.  Getting snagged on branches or vines is a pretty common occurrence while hiking.  Having things get jostled around in or on you pack is pretty common. 

Bottom line is that I assume their Corporate attorneys have to review any changes to safety features and I’m not sure if 3 or 4 people having trouble trying to charge the device while hiking instead of at night in their tent is a compelling argument.  But who knows.  Maybe they’ll allow users to disable the safety feature in a future update.  Tough to predict. 

Bugs the heck out of me also, as I suspect it would for the majority of hikers. I also have other vehicle use cases where I would prefer the unit stayed on during periods where the external supply dropped out. 

Ideal situation maybe a configuration setting to select either behavior. 

A majority of hikers do not travel trails etc with cords hanging about and plugged into thier GPSr. The battery in this device can last a full weekend with moderate use,  and recharges faster than you can overnight. 

Part of your first sentence said it all.  "Give users the ability." That is what I want the ability to choose if I'm relying on external power or relying on the device to be on.  The safety of it for me is the exact opposite of your post I rely on the device to be on if I powered it on and not turn of on it's own. I personally would like that choice. I don't see any need for attorneys to make the change as you can already turn off other more important features that would affect safety. On top of that the inreach mini originally had no way to disable auto power off but they added it with an update and now you can disable it

I disagree about more important features. There isn’t any feature that’s more important than power.  Without power, you’ve got nothing.  

Honestly, I don’t care if Garmin adds the ability to disable auto power off and you disable it.   I won’t be disabling it.  But you definitely should.  I was just trying to give my opinion as to the importance of that safety feature for those reading this thread now or in the future that may not fully understand the significance of the Auto Power Off when external power is lost without their knowledge …..and maybe haven’t thought it through…and understand that without that safety feature, their battery will begin to drain without their knowledge. 

Stay safe and good luck.  I won’t be commenting any more in this thread.  

The problem is, that 66i decides to switch itself off even when connected to external power at no predictable intervals.

When having 66i let say in a vehicle, fix connected to power, it should be able to run on that power and switch to internal battery when the ext power is lost. This should have a configuration function to set the unit to 'vehicle mode' or similar.

The reason is, that when for example a car ist started, the board voltage drops much and devices which are not able to cope with it are switched off or reboot or what ever. Devices with internat power should be able to switch between internal and external power without any interruption of service. This is BTW an industry standard, I was building and installing tracking devices abt 20 years ago and already then it was a basic requirement to have a 'vehicle mode' setting.

I understand you were giving your opinion. I was giving mine which happens to be opposite of yours. We both have different wants and needs out the device so why should one be allowed and the other not especially when the same option I'm asking for is available on a similar device that has less features?  Your opinion is not wrong nor is mine it's just different. I can see why is certain case you might want it on even though most of the time I would want it off. I still just want the option.