[Cumulus] Some Cumulus experiences

[Eggert Ehmke]

Hello Hendrik, hello Peter,

thanks for your suggestions. I will build in a resistor too and try to 
increase voltage a little. However, the N810 definitely shows the message 
"Charging battery".

Regards
Eggert

On Tuesday 02 August 2011 12:29:53 Peter Turczak wrote:
> Hi there,
> 
> Hendrik Hoeth wrote:
> >> I think partially loaded it works ok. In this case it was plain empty
> >> and rejected to boot when connected to external. I have a separate 12V
> >> lead battery with a self build 5V adapter. It had worked before and
> >> worked fine the next day, so I think my adapter is ok.
> > 
> > Are you sure the N810 _charges_ on that adapter, or does it only run
> > without actually charging the battery? I tried a 5V supply first, and
> > while it would run and draw current, it refused to charge the battery.
> > Turns out that the Nokia chargers actually supply a slightly higher
> > voltage, around 5.1-5.2V if I remember correctly. So I changed my DC-DC
> > converter and voila, it works.
> 
> While building my own adapter for the N810 I stumbled across the same
> problem. When the current of the adapter is _not_ current limited the Nokia
> devices will consider it a "special" cable. See
> http://www.herjulf.se/solar/charge-station/Nokia_2-mm_DC_Charging_Interface
> _Specification_v1_2_en.pdf for details. The N810 expects a source resistance
> of about .5 Ohms. I cracked open a cheap 3rd party charger and found a .56
> Ohms/1W resistor in line with the +5 Volts ;). I used four parallel 2.2 Ohm
> resistors to have enough heat dissipation.
> 
> Fliegergrüße,
>   Peter
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