Busch and Muller Luxos-U review

[Chris Heg]

I got one of the new Luxos-U lights when they first came out in
February and and I used it on the Texas Stampede 1200k this month. At
first I didn't like the light pattern because there is a lot of near-
field banding out to the sides but after using for many dark hours in
the wilds of Texas I am convinced. The light illuminates the whole
road from edge to edge nearby and casts a very good beam down the road
with an excellent cutoff at the top so you can control how much light
shines on drivers coming the other way.

The main reason I got the light was for the auxiliary USB power outlet
for powering my Garmin 705 GPS on long rides. For the most part it
worked well. As far as I remember it worked flawlessly during the day.
At night on days 3 and 4 there were some conditions where the charge
function shut down. I was not able to nail down those conditions but
then my brain was not firing on all cylinders at that point. I am sure
that it was due to discharging the buffer battery in the switch but
not sure why it happened sometimes and not other times. The backlight
would go out and the GPS would indicate "external power lost". I would
turn on the backlight and wait an indeterminate amount of time and the
charger would come back on. Not always, though. At least once I came
close to a low power shutdown of the GPS when the charger did not
reactivate. In that case I did several things like switching the light
off and on, unplugging and replugging the switch cable, unplugging and
replugging the GPS cable. One of those things must have worked because
the power came back.


Busch & Muller says:
"Before a USB device is connected, cycle for some minutes with the
light switched off so the cache battery has sufficient basic charge.
Permanent USB charging with more than 100 mA is only possible when all
light functions are switched off. When the cache battery is charged,
simultaneous charging and use of the light function is temporarily
possible.

The duration of this depends on the charging status of the cache
battery, the cycling speed, the quality of the dynamo and the energy
demand of the connected USB device. While the cache battery
discharges, the light output diminishes. As soon as the light output
drops below 20 Lux, the USB energy is interrupted. The light will not
deactivate during cycling. "



I don't know if the demand from the GPS varies significantly other
than with or without the backlight which I ran all the time, even in
daylight. One thing I found out later is that my total average speed
(including stops) for each day was 12.7, 11.4, 10.2 and 9.7 mph, due
to headwinds and attrition, so it may be that I was just not putting
out enough juice. All in all, I was happy with the performance of the
charger but was is not plug and forget. If you are stronger and faster
it should serve you well.

The light itself will not win any prizes for beauty. It's a hunk of
shiny plastic about the size of a lemon. If that's a major factor you
might be happier with an Edelux or IQ Cyo or something like that.

[j schaller]

I have been running a Luxos-U this spring as well and use a Garmin 605 to find my way. I've found it best to recharge the GPS during the day when the light is off. I unplug it when the sun sets and plug it back it at dawn. This has worked great so far as the internal battery on the 605 runs for something like 15 hours with the back light off, (it only comes on when the turn warning goes off) so there is plenty of juice remaining when the sun comes up. Once it's plugged back in with the light off it only takes an hour or two of ridding till it's re-charged to full power.

I have discovered one other trick. occasionally the short USB cable I modified to run from the switch to the GPS will rattle loose and disconnect causing the "external power lost" window to pop up. A careful re-route of the cable fixed the issue and now the Garmin runs just fine.

As far as the light itself goes, all I can say is amazing. Tons of light near and wide with a strong spot out front. It changes intensity with speed to keep the near field strong while climbing and boost the spot when going faster. I run it with a SP dynohub and each time I ride with it wonder how we ever navigated with the halogens of old.

[David]

Was there any rain on the Texas Stampede?

I also got the Luxos-U recently and used it on a 400km Brevet that included 14 hours of rain (but with it placed at the base of my front brake mount, above my fender and just below my Ortlieb handlebar bag, so somewhat protected.  I was not able to try the USB charger since the instructions warned not to try it during rain ... kept the cover on it.  A few days after the event I could not get the light (or charger) to work at all, and I saw condensation on the inside of the glass lens.  So I have returned mine to the retailer.

I have decided that I should keep absolutely necessary functions to finish a long brevet or randonee (i.e. good lighting) separate from "nice to have" functions such as GPS recharge without a need for batteries.

I would love to know if my experience was just a random event, if I did something wrong (other than ride in the rain!) or if others have similar problems. 

[Chris Heg]

There was no rain in Texas but I have used the charger in the rain
here in Washington State. What I did was to make a molded protective
covers for the cable connectors in the following way:

-Sand the plastic around the ends of the cable connectors
-Coat the mating faces of the sockets with vaseline
-Use a silicon adhesive/sealant to form boots around the connectors
and mate them to the sockets. Any sealant that stays flexible when it
is cured will probably work.
-Form the boots over the exposed metal of the sockets and let them
cure.

The vaseline keeps the sealant from bonding to the plugs but they
seems to work well enough as a seal (so far). The problem you had
sounds like a manufacturing flaw in the light. I hope they replace it
for you.

[Chris Heg]

There was no rain in Texas but I have used the charger in the rain
here in Washington State. What I did was to make a molded protective
covers for the cable connectors in the following way:

-Sand the plastic around the ends of the cable connectors
-Coat the mating faces of the sockets with vaseline
-Use a silicon adhesive/sealant to form boots around the connectors
and mate them to the sockets. Any sealant that stays flexible when it
is cured will probably work.
-Form the boots over the exposed metal of the sockets and let them
cure.

The vaseline keeps the sealant from bonding to the plugs but they
seems to work well enough as a seal (so far). The problem you had
sounds like a manufacturing flaw in the light. I hope they replace it
for you.


On May 24, 3:51 pm, David <davidgl...@gmail.com> wrote:

[Antti]

I tried to charge Edge 800 with Luxos U, but got some notice like "Edge doesn't recognize the computer". Maybe an USB in USB out chargeable battery might be a better solution? Or should I try some other cable than the one which came with Edge?

Otherwise, there is much more light than with the older model IQ Cyo. Side by side comparison from Saturday Night Ride: We rode side by side with Luxos U and IQ Cyo. The road was well luminated by the whole width for 20...30 meters forward (just an estimate, not so exact measurement). When IQ Cyo was switched off, nothing seemed to change. When Luxos U was switched off, maybe one third of the road was illuminated.

[Kole Kantner]

The original Edge 800 firmware included a bug that did not allow
operation when plugged into a USB power source. Updating the firmware
appears to make the Edge 800 work with all USB cables, unlike the Edge
705 that requires a specific type of cable with sense resistor that
allows operation while charging.

Kole

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[Bill Watts]

I'm getting ready to fit a Luxos U to my bike, and then set out on a month of travel in Europe,and I was wondering, Chris, if you could say something more about how you waterproofed your Luxos.  Where, exactly, did you apply the silicone?  Did you put it on the USB cord, or on the light switch housing the port?  Did you worry about the connection between the light and the line to the switch, which already appears to be watertight?  

Bill Watts

Rusa 5365

[Dave Thompson]

I used the Luxos U during the Shenandoah 1200 and Gold Rush 1200.  In both cases I had monsoon conditions part of the way.  I'd prepared for it beforehand, with the USB port facing the rear of the bike behind my little top-tube bag but also encased in the end of a plastic bag with the cords (USB included) sealed as much as possible with electrical tape.

I keep my Garmin 705 constantly charged and the backlight on 24x7.  The only time that I ran into issues was when I stopped on a very steep grade on the Shen and left the light on until it shut down, discharging the onboard battery.  I also ran the 705 with the backlight but not charging, therefore discharging it just a little bit. 

Oh -- I also have a wired tail-light.

Once the internal battery was discharged, I found that I had to cycle at 12 mph or faster to turn on the USB charger.  Clearly, based on my experience, the 705 draws more amps when it's not fully charged.  At 5-6mph (this was a very steep grade), the light would flicker like a strobe.  This was when the internal battery was discharged.

On the GRR, if I had to stop, I turned off the light, therefore not discharging the battery and never running the 705 even part-way down other than for a few minutes.  The only time on the entire ride the 705 lost external power was on the Janesville Grade. 

I also found that the electronics in the light will first turn off the tail-light and then the USB charger, in that order.  That's ok if you have a wired tail-light with built-in stand-light.  I also use a battery operated light so I was never without something showing from the rear.

Perhaps I've been lucky and have not been affected by the rain.  The USB is always connected, but with that bit of plastic bag.  I did not bother with the connector covers at the back of the light; don't know if that makes any difference plus or minus.  I have not done any other waterproofing.   

Dave.

[Chris Heg]

The silicone went on the exposed metal on the outside of the connector that plugs into the Luxos charger.