Hello Everyone,

I have been a long time lurker of this board and decided that I would come out into the light to ask a question.

I know that the N900 uses the recent standard microUSB for charging and also data transfer. My question is can anyone confirm that the microUSB charging functions work with another brand microUSB charger?

I know that seems like a strange question as "standard" means it should work regardless however live and learn my N97 will not charge from a large portion of microUSB chargers even though the voltage output is the same as an official nokia charger.

Just curious if anyone has tried and what their results were. Working in a place where we have several brand chargers it would be nice to not have to add another one.

I too would be interested to know this. Also, as I understand it some of the newer N series phones (I have been told definitely the N85 and N86 but not sure which others) can be charged from a USB port on a computer but only if the battery is not completely dead when beginning charging. Apparently if there is no power at all you can only get the unit to switch on by plugging it into a mains socket. Has anyone experienced if this id the case with the N900?

Very strange, my i8910 seems to work with anything I plug into it...

I don't know the real answer, but I can suppose ONE answer.
I have the same issue with my old Sony Ericsson M600... it works on the computer, but not on the in the car. Maybe the USB protocol should have some recognition behaviour for the devices and the Nokia filter it.
I'll try to make an example:

Nokia connected to the PC:

N: Hi! I'm a Nokia... who are you?
PC: Hi Nokia! I'm a PC... how can I help you?
N: Just give me some voltage... nothing more! Thanks

and then the Nokia charge

Nokia connected to the car:

N: Hi! I'm a Nokia... who are you?
Car: brum brum brum
N: WTF! I don't trust you!

and the the Nokia doesn't charge

Actually, I don't really know how the USB protocol works, but I think it could be something like this. I hope someone could explain it better

Somehow I doubt there is any communication going on at all with a AC charger. Maybe the failures are due to various quality of cables used and the phone not sensing sufficient voltage/current on the USB pins. This happens quite often with portable hard drives as well.

That's true and once I thought it too... but the charger[0] is big enough to have a chip inside it which sends the right command to the phone.

However, as I told, I didn't know how USB works, then these are just assumptions

[0] http://www.nokia.it/telefoni_accesso...-charger-ac-10

'Normal' USB is limited to 0.5A supplied from a USB port, and possibly less for a device with no intelligence to negotiate with the USB host.

However, there are defined specs in existence for battery charging via USB at up to 1.5A, including methods to recover from dead or weak battery modes where just connecting an unregulated 5V supply would not be sufficient (or even safe in the case of Li batteries).

I have an HP GPS which will run happily from a standard USB socket, but does not actually charge the battery, since the current draw of the unit is limited to the power required to run it. However, plug the same USB cable into the supplied charger and it will run and charge at the same time.

Have a look at http://www.usb.org/developers/devcla...arging_1_1.zip for one scheme (though I'm certain there are others, the HP seems to use a different arrangement). Nokia is listed as a co-author in this document though.

Good information and also glad to hear I am not the only one whom has experience this.

I mainly wondered if older microUSB chargers lacked the ability to communicate with a newer protocol. I honestly don't know because I have no real way to test the charger other than the output of the charger.

Strange, how certain microUSB chargers either to a computer, car or ac outlet act so different. Going to give those links another read over as well, just did a fast skim over them while at work.

Thanks again

I would wager that n900 will behave same as n97.

Fufthermore I'd make a guess that it will not charge if it's just provided power, it needs to either negotiate for power with the host system on the other end, or detect the device on other end as a charger.

I imagine charger detection is done by shorting the data pins together. Alot of old chargers just supply power, and are thus indistinguishable from sleeping computers (which might not survive attempts to eat as much as you can get)