It's been one and a half years, but let's see.

Stand by eats more than off, obviously. A powerup cycle takes about one percent of the battery. A normal sleep cycle takes about 8%, about one per hour. You can get that from quoted standby times from product page.

So, surprisingly, turning something off eats less battery.

Also, you can install battery graph yourself.

Also, you can search forum for batterygraph screens, battery threads that span for years and some efforts from several people that do battery tests (such as the battery test thread).

Have fun.

it looks charging the battery of n900 is costly for you,why don't buy a charger instead of getting it on rent!!

I tested it few times with bq27200-0 module (cause batterygraph and other programs like that use stock battery info sources, that are incorrect). Results were as follows (N900 always charged "from 0" to full, then left for 30 minutes before test):

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cat /sys/class/power_supply/bq27200-0/capacity = 99

Turn off - Wait 8 hours - turn on

cat /sys/class/power_supply/bq27200-0/capacity = 98

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cat /sys/class/power_supply/bq27200-0/capacity = 99

Off-line mode for 8 hours

cat /sys/class/power_supply/bq27200-0/capacity = 94

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Surprisingly, it turns out that standby mode eats more battery. Long time ago, in stone era of mobile devices, i was turning it off for night. Then, following popular opinion that in smartphones / extra low-power mobile computers world bootup eat more battery, i switched to offline mode for night. did it also for my N900 for weeks, but i always felt that my battery last shorter. So finally did this test and coming back to switching off

Erm, popular opinions aside, no device eats less in standby other than off, ever. If anything, that little red LED eats a few as well.

As for powerup consumption, that's another myth-y thing that popular opinion is wrong about. If it were true, and powerup took something hefty, like 10% of the battery, then there ideas would be true:

a) Plug it in, it powers up, unplug it after 10-15 seconds after power up and it would be full. It's not, it can't be.

b) A battery is typically over 1000 mAh at 4.2 volts, that's 4.2 watts. N900 is 5000 mWh, and 10% of that is 500 mWh. That's 500 mW for 3600s, that's 1800Ws, and on a 10 second powerup you'd need to eat 180W (my math may be off it's really late). Point is, it would be glowing inside, smoke would come out, stuff would be having funny smells. In reality, 1% approx (actually, less than 1%, tests on forum have shown) spread over 30 seconds give us about half a watt, which is also a nice guess for a powerup cycle. n900 can eat up to 2W if you really try and boot-up isn't particularly heavy. Video encoding isn't up, e.g.

c) If that were true, no device would ever turn off, not really. It would just pretend-off, but actually stand by really deep, so it would insta-boot. Many devices do this. Some DSLRs do this to have instant-on, some notebooks, some PCs (ASRock has a nice instant-boot trick).

Normal appliances don't really turn off for convenience of touch button start, TVs and such need to keep time and the IR receiver. Non-touch ones, like toasters are really-off.

All this started a while ago, when someone with a poor grasp of math and physics (isn't that how all myths start?) found out that lights experience a surge when powered up, because cold filaments have a lower resistance. While true, the surge is the equivalent of 0.1 seconds of consumption (rounded), so it's not really there. And from there on, it spread like wildfire. As did battery formatting, battery memory, charging techniques that are almost always wrong.

It's so deeply embedded into the history that so called experts compile this info into whole books of unknowledge and then it ends up on lesser manufacturer's sites, in "expert's" training and I have seen manuals that came with batteries that gave plain wrong advice for the chemistry they sold.

(
Good information if you want it can be found on wikipedia, high-end manufacturer sites and specialty sites that don't have a Geocities-looking site. For batteries, batteryuniversity.com is a good read if you have the time. Professional charger manufacturers also have the right idea, like Maha. Those guys built chargers 3 years before Panasonic recommended the same charging technique (burst charges).
)

This includes self-discharge times, load types and profiles and many more.

As for the ultimate battery advice, here's the bottom line:

* Li-Po batteries hate the heat. Keep them cool. (Really)

* Li-Po self discharge (very slowly)

* Li-Po hates being fully charged or discharged when stored.

* Li-Po has a shelf life of about 10 years if charged 40-60% and kept in a dry environment at 4 degrees Celsius.

* Under normal use, a Li-Po has about 1000 cycles until it starts to be visibly lacking, that's about 3 years. Also, they tend to get ruined because they aren't kept in a half-charge at 4 degrees, so they start to break down after about 3 years. So, charge daily or you're saving for the dead.

Personally, I plug the device at night (about 2 AM) and pick it up at 9-10 AM, fully charged (96%). Every day. If it runs dry, I charge for a short while. After 18 months+, there is no visible damage.

Oh, and, because of the charging technique:
* Batteries charge faster from wall wart than USB or other emergency chargers

* Batteries charge faster in the lower range than higher. It sucks up 10-15% in 10 minutes when at 20%, but it takes 30 minutes from 86 to 96. So if you have a choice, aim low.

That's it for now.

ndi, thank You for very useful info. I will definitely look at site You mentioned - anyway, i think that i was ''victim'' of one of those myths, no matter that I'm not totally newbie in terms of battery maintenance. Even with Li-poly i tried to discharge them at least to 3,5 V before charging to full - yea, i know that origins of this come from NiCd/NiMh batteries, but i thought that 40-60% charge should be used purely for storage, i.e days/weeks/months without use.

So, we can sum up, that letting li-poly to go down only to 40%, then charging to semi-full is best to keep them alive and healthy? That is what you do by charging every night, or i missed something?

Also, just one little correction - N900 stock battery got 5W (4,9W in fact), so bootup can't use 0,5W, cause it would be... mentioned 10% Anyway, I got main rationale. Maybe someone will correct Your calculations, but that is pure cosmetic thing. I won't cause im after 24h without sleep so my calculations can get even ''better'' results.

A small correction: your power calculation is flawed, because the voltage isn't a constant.

Apart from that, my unscientific experience is that the powercycle and a night in offline are not very far off, so I take the fastest and most convenient way - I have AlarmD switch it to/from offline mode automatically

EDIT: did two powercycles and battery-eye shows a 3-4% drop caused by the reboot.

If we're talking 1 day or more, I agree it is better to power it off.

Do the same as me: charge your N900 at work. Save some pennies on your electric bill

petur:battery-eye, battery graph and other things like that seems to cheat. According to both, i many times run for hour or so with under 0 capacity I would rely on bx2700 module, which is showing 1% for powercycle - as ndi already mentioned, it is something under 1% in fact.

Ps.

It's funny how battery-eye/graph react for powercycle - doing it all the time in loop for 20-30 times you Can probably reach -50 capacity (but wasn't be able to see it on graph, line will be just under visible area) and then use N900 for half a day.

Actually, that's not true of NiCd nor NiMh. It doesn't help a NiCd to discharge below a voltage unless you are in very confined, non-standard scenario, like the memory droop. The effects of partial charging to a battery is negligible.

I charge as I can, and I try to make it to home. Sometimes I charge at night at 40, sometimes at 56 (if I forget about the phone) sometimes at 0.

Ideally, a pattern exists, but if you go ideal you can't use the phone or it forces you to shut down or stop using.

Lithium Ion (BTW, it's the same chemistry as LiPo, the differences are negligible, in fact it's called Polymer Lithium Ion) is quite delicate in some areas, quite strong in others. Don't worry too much, try not to abuse it.

abuse:
* heat (bad)
* cold (ok)
* overcharge (very, very bad)
* overdrain (very bad)

The last two are managed by the chip inside the battery AND the N900, so it's fine. Keep it at a reasonable temperature.

It eats cycles if you charge it for no reason - some people charge 5 minutes when in an office. This is bad, a 5 or 10 minute cycle counts as a cycle, and if you do this 3 times a day, in a year it'll be dead.

Also, it is very bad for it to be discharged. Phone shuts down when it's low, but if you leave it like that for a week it will go below the safe level and be destroyed.

So, you know, as needed. If you try to charge every OTHER day but don't make it ans it has to stay for hours on zero, it will probably give out before a battery that has been charged daily. If you charge 5 times a day, again, bad.

So charge as needed, try to charge fully so it would have autonomy and not go through cycles (that's why I charge overnight, full charge every time). Mine usually takes me through the day. If it doesn't, I charge it again when it becomes low. This means that, on average, I get 1.1-1.2 charges a day.

No, actually, you missed the unit. N900 battery has 5 Wh (the little h isn't a typo). That's watts-hour, meaning it can put out 5 watts for an hour. The bootup sequence eats 0.5 W (notice no h). To eat 10%, it would have to boot for an hour straight.

When peaking, the device eats 2W, so 5Wh lasts for 2.5 hours.

And yes, as it was mentioned, my calculation is off. The battery doesn't do 1250 mAh at 4.2V, since the voltage drops. If it is linear, it averages 3.8 (4.2 to 3.6), by 1320 mAh(as per specs) is 5.016 Wh.

I knew it was 5 so I just cheated the math and pasted the result :P

Ehmmm ... I can't really find much fault with the calculations, actually. It was an approximation to start with, and battery really is 5Wh, 10% is still 500 mWh and dissipating 10% of battery charge in a matter of seconds still yields blue smoke.

And explodes (lights, actually, it's a rapid flame) the battery, most likely, assuming a phone thingy can output anywhere near the required power to heat the core over 60 Celsius. Point is, it's not 10%.

As for using battery module as opposed to native HAL, it's not like that. Battery level is a complex thing without some electronics, and the percentage is a decaying average based on consumption, load and voltage.

It is not wrong, it is helpful. Rebooting the phone erases that backlogged average so the phone guesses based on voltage alone. That's why reboots mess up the percentage, not that percentage is unreliable.

I found the battery kernel module to be incredibly annoying. The thing simply assumes that voltage is percentage and it varies wildly. After quiet periods, it shows 75% even though the battery is over 50% gone. Other times, it simply panics when I know it's fine.

Overall, the Nokia percentage calculation is pretty good, if you know how it works. Batteryeye is a nice program, and it logs and shows, it does not presume to show any percentage, it is up to you to determine droop, fall rate and guess your own capacity.

Good capacity software could be written, but Maemo is kinda dead and the few good people we have are busy fixing stuff, not polishing battery guesstimates. And good for them.

Other phones have the same battery and charging principle and work to the percent because they gave a *** when they wrote the OS. Nokia didn't, because Nokia still uses indicators that read "full, full-ish, 'bout half, empty-ish and red". For that kind of precision (and they round up to counter human factor) there is no need to estimate anything.

You and your percentage. Kids these days.

I'd like to see some references for your claim that a partial cycle equals a full cycle.

Considering that what the N900 (and almost everything else) does once the battery reaches full is let it discharge 2-5% and then top it up again, it should be burning through a large amount of "cycles" once it reaches full. (And the green light comes on independent of whether the battery is actually full at that time or not, and stays green until charger is disconnected)