As long as wallchargers comply to the USB charging spec it should work with n900. There were many, and there are still many nonstandard chargers made that will not work.
The USB spec says chargers should identify themselves as chargers by shorting the datapins together.
The phone can tell if you are charging from USB or wall-charger - it shows up in the "hal-device bme" output.
I'm using an after-market micro-USB wall charger rated at 550mA, and it seems to be OK.
Does anybody know what the allowed input voltage range is?
Since it has a switch mode supply insode, it would be nice if they specified a range.
I'd like to be able to charge or power it from an external battery, and it would be inefficient to have to add an extra DC converter.
You'd expect 4xAA NiMH to do the job, but would a 2-cell LiIon be too much? (8.4V max unloaded)
I found the document
Nokia_2-mm_DC_Charging_Interface_Specification_v1_2_en.pdf
Max input voltage is 9.3V, so I guess it would be safe to try the 8.4V LiIOn??
I don't know if that would meet all the other spec's, such as capacitance.
The USB standard specifies a much narrower charging range, but the N900 officially can be charged by the 2mm charger, using a simple adapter.
I found the document
Nokia_2-mm_DC_Charging_Interface_Specification_v1_2_en.pdf
Max input voltage is 9.3V, so I guess it would be safe to try the 8.4V LiIOn??
I don't know if that would meet all the other spec's, such as capacitance.
The USB standard specifies a much narrower charging range, but the N900 officially can be charged by the 2mm charger, using a simple adapter.
I'd be careful just assuming "simple adapter" will do. I noticed that when I do plug the Nokia charger to USB adapter piece supplied with the N900 into my old AC4 adapter, the AC4 starts to make slight whining noice without anything else connected. Also, the "simple adapter" does get a bit warm during charging. These two facts alone suggest that there is indeed some electronics in that small adapter. Most likely it is a post regulator to step down the higher voltage coming from the old style charger into a USB standard +5V.
While it is possible the N900 will be OK with higher than 5V, I'd not dare to try it myself...
i ordered a spare battery(official exactly the same)- it wont charge on the provided charger, but it will charge with an old nokia charger and adaptor..
Also, the "simple adapter" does get a bit warm during charging. ...
Damn! I was afraid of that. My CA-146C is still on order, so I have not had a chance to test it. The DX one claims to be "genuine", so I hope that means at least an authentic copy.
My plan was to put a 2mm plug on the battery, and use the CA-146C adapter with the N900. That may still work, just not as efficiently as I hoped. Still, probably better than using a car-charger to convert.
The idea was to be able to take the n900 backpacking in the bush for a week, so the less weight of batteries, the better.
Can anyone confirm if the N800 will work with 8.4V in? It should according to my limited understanding of the above document.
