Today was my first test ride for the new power supply device chain: new dynohub SON 20R, JaWeTec Bikecharger, SwissBatteries PowerTank M, Garmin Oregon GPS without internal batteries, Schmidt Edelux lights playing all together. I did some short slope of probably 45km with some 1300m of elevation. Most of the uphills were too slow to keep the bikecharger charging the Powertanks internal battery, so I switched it off at uphills and let the Powertank drive the GPS on its own. At first image those two Powertank LEDs are visible. A red one indicating charging state and a blue one indicating some device at USB out consuming power.

With such short ride I could not enforce any power outage and I could not determine whether the GPS would empty the Powertank quicker than it could be recharged by the bikecharger. No problems today. The Garmin GPS ran continuously without internal batteries, performing routing, showing maps, trip computer and several other jobs permanently. No power saving mode, but no backlight, though.

Charging of the Powertank starts at less than 10km/h with the SON 20R dynohub. As soon as speed goes further down, one should consider switching off the bikecharger to protect the Powertank from those remaining slow pulses at DC out of the bikecharger no longer being able to provide constant voltage from dynohub out.

There is one more interesting experience: with the SON 20R there is no need to switch on the lights when reaching speed of 50km/h to protect the bikecharger from dynohub overvoltage. Actually the charger would switch off itself automatically for that reason. I had to take care about this when using the stronger SON 28S dynohub.
On the other hand, I found out, as soon as switching on the lights, there is not enough power to charge the powertank, no matter how fast I am riding. With my previous installation it looked as like there was enough power left to charge the GPS even when lights would shine, but there definitely is not. The Powertanks red LED will not even flash slowly with lights switched on. So that was not a very good idea, anyway. Something that I will no longer pay any attention to.

Finally some words on installation and weight: the whole collection of USB devices and cables including GPS but without dynohub and lights makes up 342g. See third image. Installation looks some kind of messy at the moment, but everything will be protected by some small bag mounted at top tube. At final stage there will by two wires from the top tube bag to handlebar and the GPS at the handlebar. Should look quite clean. Need to get appropriate bag.

Fig.1 shows two screenshots of two different tracks in different scaling on topografical Oregon 400t map. I like the clear and pretty map drawings. This map does not contain trails and gravel roads mostly, but nevertheless it gives a good impression about topografical layout providing good readability. Also, it provides a surprising amount of roads and city streets enabling road navigation capabilites by means of uploading tracks generated with google maps or whatever. This works pretty well but certainly lacks automatic rerouting, also needs an internet computer for planning the route and creating a GPX file to be uploaded to the Oregon.

Fig 2.: Track displacement example: some sloped section ridden downhill with GPS mounted at handle bar in horizontal position (left image) and ridden uphill slowly with GPS carried in back bag of trikot. Although riding much faster and therefore creating less track points (visible at image), the sooner downhill track recording is by far more acurate than the latter uphill track.

Fig 3.: These are two track screenshots of an uphill (and back downhill) ride onto the Zwölferhorn summit at our area. Left image shows track overview within topografical 1:100000 Oregon map. Right image shows topografical 3D profile of this track section from birds perspective, a feature that I like very much.

All those screenshots were directly taken from the handheld, no postprocessing.

Bicycle Holder Installation

Within the last weeks I have been gathering some practice with my new Garmin GPS, an Oregon 400t model. It was attached to my MTB, the Big Dummy, a motorcycle and a scooter. Finally I installed two bicycle holders, one at the Big Dummy and one at the scooter. I will need to buy at least two more of them. The Garmin bicycle holder for Oregon and Colorado models is simple and cheap, but it is not ready for hard bumps and impacts, probably dropping the device incidentially. Thus I had to feed in some layers of soft rubber tubing to prevent heavy shattering of device. While this was possible in an easy and efficient way at the scooter due to its thin handle bar stay providing space for a thick rubber layer, at the Big Dummy I had to keep my anti vibration layer quite thin due to thick 31.8mm handlebar. See images to compare both mounts. Nevertheless, I am hoping there is enough rubber to make it absorb hard shaking and keep device in place.
There are several GPS mounting systems available as like Bikertech customized, Ram Mounts, Touratech and probably lots more, most of them fairly well addressing the oscillation issue, but in my opinion they are way too big and heavy for my small vehicles, also quite expensive.

Power Source

Lengthy trips require some thoughts about GPS power supply. Batteries may be sufficient for one or at most two days of continuous use. Some battery charger will be needed most likely, since the Garmin would never recharge its batteries inside when plugged to some USB power supply.
Trying to avoid another battery charger in my baggage, I connected the Garmin to my hub dynamo via the JaweTec Bikecharger mentioned previously here. Basically this works, but it is far from being a perfect solution:

• With the SON 28 dynamo a continuous speed of at least 10km/h is required to provide enough power for the device. As soon as riding slower the GPS will start beeping and switch to battery if possible or just shut down.
• The charger is not recognized as a simple power supply. By default the GPS goes to mass storage mode when the charger is switched on. To prevent this, the devices USB interface needs to be set to Garmin Spanner mode, which means, for every short power outage one needs to confirm switching to GPS mode instead of mass storage mode at some popup window coming up with a nasty beep, again and again. Thats sort of cumbersome.

For the motorcycles there is no problem about power supply since it can simply be wired and plugged to the battery via some modified USB converter taken from my previous navigation device. Thus I can run it without any battery inside which is strongly recommended with offroad usage. For the Big Dummy I am still in search for a better solution. I may probably connect a special battery charger to the JaweTec charger and keep a pair of fresh batteries there, but actually I do not really like this, since it requires taking along too many small devices and batteries. I may probably just get a small and lightweighted charger and recharge batteries every night, leaving the JaweTec charger at home.
Another feasible solution would be the dynohub driven Zzing USB charger providing internal battery buffering (unlike the JaWeTec charger) for devices not being capable of USB charging. This way the Oregon GPS could be used totally without its batteries (keeping it lightweighted with better protection against bumps and vibration). However, the Zzing charger is quite big.
As to some readers comment the Australian company Pedalpower+ provides DC hub generators and several more interesting mobile power supplies for bicycle usage.
I finally decided to stick with my reliable JaWeTec charger and put some USB chargeable power buffer, called PowerTank by SwissBatteries in between the charger and the Garmin Oregon. I will give it a try and report about it.

After quite a long period of evaluating GPS web pages and newsgroups, searching for test reports, user experiences and talking to people, I got totally submerged by chaotic information overkill. Finally I decided to replace my Medion automotive GPS navigation device with a real outdoor GPS, the Garmin Oregon 400t (European model with 1:100000 topografical map covering most regions of Europe). This device will be mounted at the Big Dummy mostly, but will also be used for hiking and motorcycling. Currently I cannot tell, whether it will be possible to run it with my unbuffered dynamo powered USB charger since the Garmin device will not use and recharge its batteries when being plugged to an external power source. So, when riding slowly, the Garmin may simply shut down. I will find out more about it.