Hi,

I've got two of my three batteries into a weird state. When I put them into the N900, it refuses to start: no white LED at all. When I plug in the charger, the orange light very briefly flashes on once (in fact, it seems more intensely than usual), and then it's dead.

Using a multimeter I can see that there is power in the battery: I've tried the battery with 3.5V, 3.7V and 4.08V and 4.22V. At all of those voltages the two batteries behave as above. I also found I can run my N810 off these batteries (using an ingenious system of elastic bands).

My third battery still works fine.

The way I got the batteries into this bad state was by charging them in an external USB charger: one of those little keyring charger gadgets:

http://www.sourcingmap.com/mininatur...n-p-27419.html

It seems it may be overcharging slightly, up to 4.22V. But what I noticed is that when I only charged the battery a little way in the charger, the N900 did boot from the battery, but shortly afterwards crashed. So it seems like something had already gone wrong.

So my questions are:

* Does anyone know what that brief orange flash means? Is it a particular message from the firmware, or is it just some piece of power circuitry dying?
* How can the N900 possibly "know" that I've been charging in the USB gadget, given that the N810 is perfectly happy to use them?

Thanks for any help. And if anyone else is thinking of using one of these keyring chargers, I would highly recommend not doing so!

The charger chip in N900 has direct path to make orange on the LED, but I imagine normally the led would be under software control and driven by the dedicated led driver.. FWIW, the led flashes for me when I plug in charger with powered-on N900 too.

Out of interest, could you measure the resistance between - and third pin on all your batteries? Would be interesting data..

Interesting that the LED flashes on your phone, it doesn't on mine when it's powered on. It might be meaningless. My next test will be to put in a dead battery and leave it plugged in overnight, maybe some magic will happen.

The resistance is 100kOhm, on both my "dead" batteries. It's 120kOhm on my BP-4L batteries for the N810, and 47kOhm for BL-5CA.

Visual inspection of the terminals on the battery, comparing the 3?

Holy crap! After all that trouble, you're right, it was just physical damage to the pins. There's nothing visible, but a little wiggling with a safety pin to push the clippy bits closer together, and now it works. Hooray!

I guess this means the little USB gadget is OK, provided I don't use it too much and I bring a safety pin with me when I travel. If I keep wiggling the pins like that they'll wear out eventually, so it's just a question of how much the portability is worth to me in replacement battery costs.

Thanks for the help, and I definitely learned some stuff :-)

OK, a couple more points to clear up, for anyone else who finds this thread.

The brief orange flash when you plug in the charger happens if you take out the battery completely and plug in the charger. If you see it, a bad connection to the battery is a plausible explanation.

The other symptom I saw was that after charging, it would work for a while, then I would look at it later on and see it had mysteriously turned itself off. I thought it was crashing, but probably it means that it was bumped and the terminals disconnected.

My USB charger has triangular terminals that look almost designed for spreading the battery clips too far outwards:

http://mat.exon.name/diagrams/20100324_003.jpg

I also have a desktop charger, unfortunately far too bulky for my purposes, which has blade shaped terminals like the ones in the phone. Obviously this latter design is far more sensible.

I guess it would work better if they were rotated 90 degrees and made a bit smaller..

Just wanted to quickly check if the ORANGE LED is meant to flash even when the display is on? In mine, I have noticed recently that the LED flashes only when Display is off or the Phone itself is OFF. I am not sure if it has happened recently or is this the way it shud function? can we change it so that it flashes always as long as charger is charging the mobile? other led notifications look fine.

Yes it's normal that it's only active when screen is off.

My N900 got the same recently, my battery is about 3.4 and my phone won't turn on, it's been charging in a very similar charger like the one used by matthew_exon, but my battery is taking hours to charge or I don't know what else, maybe it is death already...

how can I test the battery? not a single 5800 around me, no x6, don't know what to do next...