Turn off wireless where not available

[wallcraft]

A Kindle Review on Amazon by P. FEng indicates that the Kindle will quickly drain its battery (1-2 hours) if you don't turn off the wireless on a plane. This is plausible, since my phone drained quickly in Canada as it tried to find service that was not available. Assuming this isn't an isolated hardware fault, it is a warning to everyone to be careful when traveling.

I agree with P. FEng that this may be is a design fault. A cell phone needs to be on to receive incoming calls. A Kindle does not need to be connected all the time, and it should have good power management for the wireless connection. I would also have allowed charging via USB, although this lack may be a consequence of the long design cycle (USB charging was less common even a year ago).

[HarryT]

Surely the LAW requires that you turn off the wireless on a plane, does it not, just as one has to turn off a cell phone? The wireless component of a Kindle is a cell phone.

[wallcraft]

I agree that leaving a Kindle turned on in your bag is a bad thing on several levels, but I'm sure there are a few cell phones in this state on every flight. I don't have much sympathy for this case, but it is worth remembering to turn off the wireless when traveling internationally (or to the rural US).

[catsittingstill]

If Kindles drain their battery when they're out of EVDO range, that's something I want to know if I'm going to be spending the weekend in Canada or something, even if I drive and don't have to turn off the EVDO for safety's sake.

I saw that review too--but I think we should consider the possibility that he just got a bad battery--some units have been shipping with batteries that drain unusually fast--like within 24 hours. Peter Svensson wrote a widely reprinted review about one of those units, claiming that the Kindle is a battery hog.

[Alisa]

I think the wireless turns off itself when the unit is asleep. I think the reviewer was actually reading and had the wireless on during the flight. The wireless is definitely quite a battery hog. My house has marginal coverage so I turn it off unless I need it. I have a Sprint mobile, too, and I find that it's battery gets eaten really fast when the signal isn't good, too. On the Kindle with wireless off, I can read for days. I read well over 1000 screens yesterday and did a little bit of playing with stuff online (checking out Hadrien's links on feedbooks.com) and my battery meter was down by less than 1mm. However, I found that my first session with the Kindle, the battery went down rather quickly. The battery meter said it had a good charge, but it was at half within a few hours of reading. After I did a full charge, though, I haven't had that issue.

[geoelectric]

Old thread, but assuming it has a typical cell radio algorithm, what it'll do when out of range is increase wireless power in steps until it gets to max, wait a fixed amount of time, then go into a sleep/wake pattern where it will check for wireless every so often. You definitely see increased power loss in this state over a normal found connection, as the cell radio will decrease its power from full based on the strength of the connection.

This is normal behavior--cell phones drain faster out of range, too. Luckily, the Kindle allows you to turn off the cell radio with a hardware switch, after which it isn't an issue. I keep mine off nearly all the time, turning it on when only I need it, plus once in the morning to get my paper (which arrives within seconds--they must have a wake routine that contacts Amazon upon turning on wireless). My battery life is phenomenal.

The other thing that will drain batteries is indexing, which happens within sleep mode (i.e. it doesn't really go to sleep fully, but stays awake to index while showing you the screen). I suspect it also keeps the Kindle from decreasing CPU/power usage between page turns. If you load a bunch of new books, you'll see battery drop.

[Alisa]

I really don't understand why the Kindle doesn't shut the wireless system down more itself. After all, it doesn't need to be on all the time. This isn't a mobile phone where you may be receiving inbound calls. The Kindle knows when you may be about to use the wireless. You've hit the Search button, selected to go to the Kindle store or opened the web browser. You would think it would shut down when not in use. It could wake up at specified times to go out and retrieve your periodical content. Seems like that would really make things more seamless for people. They wouldn't have to switch it on and off which is a bit awkward sometimes since the switch in on the back. I don't get why that switch isn't on the top actually.

[geoelectric]

I'm with you on all counts. I'm unsure how content delivery works, whether it's a push-from-server or pull-from-kindle action. If it's push, that'd explain why they're leaving the wireless up.

[bob315]

Originally Posted by Alisa

I really don't understand why the Kindle doesn't shut the wireless system down more itself. After all, it doesn't need to be on all the time. This isn't a mobile phone where you may be receiving inbound calls. The Kindle knows when you may be about to use the wireless.

I agree that an option to automatically turn off the wireless might be nice, but there are other cases where it might not be desired. In addition to initiating the transfer from Amazon to the Kindle while sitting at your computer, it may be other people who are sending you things. Documents emailed to you@kindle.com by authorized friends can show up anytime and you might be interested in seeing them ASAP. Auto-off might be less useful then.

[Alisa]

Of course. I think there should be configurable power management settings. You could have always-on or have it only come up and check for new items periodically or have it off unless you do something that requires it.