Thread: (Request)Charging from unreliable/variable amperage and Pali's new BME
View Single Post
pichlo's Avatar
pichlo is offline pichlo
2014-09-03 , 19:31
Posts: 6,453 | Thanked: 20,983 times | Joined on Sep 2012 @ UK
#2
Originally Posted by biketool View Post
The old BME supplied by Nokia would reduce its amperage draw in stages if it detected a low voltage situation
Really? I had no idea. That sounds odd, I cannot fathom what the rationale for that might be.

it would remain at this low draw even if the available power increased.
Now THAT is definitely odd.

My application is a bicycle hub-dynamo driven USB power converter, it can provide up to 1500mA at 20km/h but if I come to a stop or even slow down this obviously will drop off, the N900 will drop to nearly zero draw and will not recover unless disconnected and reconnected at speed, a difficult trick while moving.
That's a bummer and I agree a software solution would be preferrable but in the absence thereof, you can try a hardware alternative: a little gizmo that would cut the power off completely in a voltage drop situation, reconnecting it once the speed (voltage) picks up again, thus simulating your manual disconnecting and reconnecting the phone. A DIY solution with two transistors and a bunch of resistors would do the trick quite nicely.