Nuvi 855 Battery Discharge Rate

Yes, I've absolutely seen overnight battery level changes of a few percent as well as nearly a full discharge. One 855 owner reported in the past year that his unit occasionally turns itself on when in sleep mode which could explain this. I've never seen a random turn on but on the days when I see a near 0% charge just 12 hours after it had a 75-100% charge, a self-turn-on may be occurring with mine, too.

One person (possibly DorkusNimrod here) suggested removing the battery when the unit's not being used. I fought that suggestion until just recently since a battery removal/reinstallation reverts my 855 to the default Jill voice (or occasionally the non-TTS American English voice) so upon each boot up, I had to manually reset it to my preferred TTS voice.

Another issue I've had with my 855 is the 855 self-rebooting itself, which most often occurs when I touch the "Go" button for any destination when starting a route. Since I've started removing the battery every day, I find that my 855's self-reboots have either completely ended or at least are much less frequent. I don't know if the fewer self-reboots are due to my frequent battery reinstallation manual hand reboot or if it may be due to my battery being more fully charged.

All in all, several nuvi 8x5 owners have these issues and others have perfectly-behaved units. (Some with the well-behaved units feel that we with the misbehaving 8x5s are crazy, that we've failed to update our firmware, or worse. Maybe I should suggest trading my 855 for theirs )

My 855 *usually* behaves itself. I occasionally get those surprise reboots too. They can happen when searching for built in POIs or changing routes and usually when you need information quickly, such as checking if an upcoming exit has something you need.

My guess is that the unit runs out of free (heap) memory, causing the reboot. By doing a hard reboot yourself, the unit is regularly starting with all memory available. A memory leak over time can reduce the memory available until there is not enough available for a memory intensive task like calculating a route or searching.

And yes I run the latest firmware. Occasionally the Garmin support page says it has to upgrade. I check the firmwave versions for everything I can find (GPS module, unit, traffic receiver, etc.) before and after this, and nothing changes.

I pull the battery (actually just slide a thin paper between the battery and contacts) often and don't think I've had any issues with the voice resetting. I keep my Nuvi in Europe mode as I prefer the blue header line at the top to the green line in North American mode, and this always stays the same too.

I've wondered about phantom switching on from standby as well. I'm also curious if there is a difference in battery drain between using the on/off switch at the top of the unit and pressing OFF on the display after external power is removed...

I have found that my 855 will completely discharge in 1 day or less if I shut it off and then move the switch to screen lock (all the way to the right). Even tho the screen remains black, it must draw additional power when in the screen lock position. If I leave the switch in the middle position, it will go for many days before the sleep mode completely discharges it.

I know for sure my 855 will occasionally turn itself on because I have caught it doing it. A friend has also caught his doing it.

I have a 12 volt 20 amp power supply that I plug the 855 into if I haven't used it for a few days just to make sure the battery stays up. Several times I have turned the power supply off and 5 or ten seconds later the 855 turns itself on. One time I brought it in from the car when we got home and set it on a dresser in a spare bedroom, several minutes later I went back in the room to get something and it was setting there on.

Don B,
In all of those cases, did the 855 turn on after something happened, like shortly after disconnecting it from 12 volt or USB power?

Sometimes that was the case with the 12 volt supply, but I can't be 100% sure that was the case all of the times it may have happened. There were times when I didn't use it for two or three days and never went in where I had it stored, but the battery would be dead, so I have no way of knowing that if it did turn itself on did it do it two minutes after I set it down or a day after I set it down.

As I am retired and sometimes don't drive my car for several days at a time, the worst problem I have had related to this thread topic is actually the discharging of my car battery. Based on measurements I believe that the 855 left to its own devices pulls a bit over 100 mA out of my car battery when it is "off". While for those using their car daily, this is scarcely an issue, on a two-week vacation it depleted my battery enough that my car would not start on return.

Since then I have trained myself to pull out the 12 V plug for my 855 each time I leave the car. Roughly once every 20 times I plug it back in, I see the Garmin reboot sequence. I now believe that each time that that happens the 855 has somehow depleted its battery down to zero. As the 855 commonly turns itself back on when it senses that you have plugged it back in, my speculation (and hence the topic of my post) is that during the process of unplugging it it sensed the connection going from off to on, turned itself back on, and did not turn itself back off again. Something of that nature seems a little more likely to me than a completely random self initiated turn on while fully asleep.

http://www.poi-factory.com/node/33626

Excess heat reduces the charging capacity greatly. If you care about the battery life, take it out of the car when it's warm.

If I leave my 3760 inside at room temperature, on a full charge it will stay in standby for a REALLY long time. So long, that I've never really noticed it go down at all.

My car usually stays in the garage so when I get it it's cool. When I drive to work in the morning, it's plugged in, and when I get there, it's 100% charged.

If I leave it in the afternoon heat, when I get out of work, it's down to 25% capacity. If I leave it in the car during the winter, it's still 100% when I get out.

I imagine that most of us 855 owners follow your advice. I know I do. But many 855s do have phantom battery drain.

My 885t is the same. The battery drains even if I never turn the unit on.

They seem to always be in a standby mode and use up the battery.

I guess we could remove the battery until we are ready to actually use the unit. But I'd probably lose it.