I just noticed a little problem with my N900 and I was wondering if you ever had this (should this be a bug?).

I started to charge my N900 using an USB chord from a very old, very cheap PC. I'm thinking it never issued 500 mA, most likely only 100. At this rate, the N900 uses more than it gets. This does not keep the device from animating an orange LED and claiming charge even though it was actively discharging.

There's a thread here about estimating battery charge but unless it replaces the default one, user never gets notified the charge isn't sticking.

Also, under very heavy usage one might never get battery to charge under normal circumstances as well. I'm thinking either heavy usage (wifi, video, etc) or a busted program that hogs CPU or similar.

I'm thinking beeping every now and then and a red instead of orange LED?

yep it takes for ever on my pc- but then so do other phones.. what is wierd is how an olde nokia charger plus supplied adaptor takes so long to charge a n all..

this phone has issues with charging- sometimes it just doesnt even want to charge

It takes for ever because

* the capacity of the battery is 4.2 V by 1.2A, roughly 5 Watts Hour (rough guess).
* USB delivers 5 V, 0.5A, that's 2.5 W if all goes well.

As a result, it takes 2 hours to charge a battery, not counting

* overhead of charge (you must pump about 120%+ capacity to charge)
* heat dissipation (charger circuit inefficiency)
* power consumption of the running device
* loss of battery efficiency due to heat
* etc

Adding these factors, by jerk reflex is to guess 2.5 hours, but this is for sustained charge, which doesn't happen in li-po or li-ion, after a certain percentage the process is delicate and slow as to not upset the darned thing. As a result, it can trickle for another 20 minutes or so.

At this moment, my N900 just passed its 3 hour mark, knowing:
* wasn't in the red yet
* wifi is on, but standing by
* BT is on, standing by, visible
* mounted as mass storage, but not actually moving any bytes
* mail is updated every 5 mins, weather every 30

It's still orange.

Given internal charge logic my guess is no joy unless one gets a desktop charger. Then, rapid charging can go 1C for quite a while, plus topping, I'm guessing 70 minutes.

BTW, my N80 charged from off-because-out-of-juice to full in 1 hour 11 minutes. Meaning it gobbled up half capacity in like 15-20 minutes. I liked that.

in practise charging of my laptop it never cahrges fully..

and it takes 3 hours of the supplied charger

I think I saw a thread on why some older chargers take longer to charge the N900, i believe it was due to the charger being unable to negocciate a higher current from the charger. There was a hardware workaround proposed but it only fixes wall/car chargers, PC/USB charging is limited by the max current of the USB bus.

Old USB computer ports doesn't support power on USB. You may wait forever, the orange light may be just circuitry indicator but no real current...

Some USB ports have some additional power connector (inside computer box) and if you attach power from power source to it you get power on USB.

Moreover, my Dell 1720 notebook has 4 USB and I see a charge only on 2 of them.

I experienced this once - N900 connected via USB for several hours (with light use during that time) and the battery did not charge even though it indicated that it was. This was on a 1.5 year old Lenovo desktop running latest Ubuntu. I figured it was possible that it wasn't being powered since no driver attached to the USB device (charge only mode), so I reconnected in mass storage mode and it charged fine.

I have a different experience.

When I finish charging N900 while it's on stand by (this means Green LED), I switch off the device and then the green led becomes orange/yellow again, and it still charges for an extra 20 minutes.

The vice versa also applies.

I wonder what's going on...Doesn't the device charge completely while on stand by? and doesn't it charge completely when charging while completely Off?

It's kinda messy...



Bye

@s1rl4ncel0t: You can't continuously charge a battery, unless you like fire. Once fully charged, the charging circuitry will be shut down until the voltage reaches a certain point a little below full charge - at that point the charging circuitry will be reactivated. By turning your device off, you are forcing the charging circuitry to reactivate early.

If so, then this is a bug, even if cosmetic. Resetting the circuitry does nothing, as re-plugging the device when voltage is 4.2 gets you a "Battery already full", by design.