[Gta04-owner] charging gta04 on my bicycle

Dr. H. Nikolaus Schaller hns at goldelico.com
Fri Jul 11 08:55:10 CEST 2014


Hi,
the charger is a little critical about the VBUS voltage. It reports an issue if >5.2 V and drops charging if <4.4 V.

But charging is only (re)started if VBUS goes below ca. 1.5V.

So there is a situation for VBUS voltages where it does not charge even if you have 5.0V.

Andreas has modified things to make it work on a bike:
http://www.ohsw.de/gta04-otg.pdf
http://www.ohsw.de/gta04-bike.pdf

Maybe he will comment here as well.

BR,
Nikolaus


Am 10.07.2014 um 21:41 schrieb Michael Spreng <handheld-linux at m.spreng.ch>:

> Hello
> 
> In a few weeks I want to go on a bike tour, with my GTA04 as
> navigational aid. Because the battery only lasts for 2 hours with full
> backlight and GPS enabled, I have equipped my bike with a USB power
> converter for the dynamo. But it doesn't seem to work. I have my battery
> log attached. Between 12:14 and 12:25 I was riding my bike. But it looks
> like the battery drains even faster than normal while it is hooked up to
> the dynamo. It was in standby (or at least the screen was turned off, no
> GPS running) while I was cycling.
> 
> One of the problems could be that the power varies a lot while cycling.
> Each time I stop the charging stops, and in the beginning the available
> power (mA which can be drawn by the GTA04) is limited until I have
> accelerated to the usual speed. Which might confuse the charging logic.
> 
> Has anyone any Ideas how I could improve my Setup to be able to use it a
> whole day? How I could get charging working from the dynamo?
> 
> Thank you
> Michael
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