Busch & Muller Lumotec IQ2 Luxos U and SONdelux K687 problem

[raymondoyo]

I would be grateful if anyone could help. I have one of these lights which has been fine, until now.   The light used to have 2 settings, high and low, both steady, and would hold power for a few mins when stopped. Now the light is low only and flutters all the time, and does not remain on when stationary. I am wondering if i just have to get a new light to see if it is the light or the dynamo or both. Many thanks

[Kim]

Almost certainly the light, probably the battery within it.

Worth checking your wiring though - there might just be bad connection or a short somewhere - and disconnecting the rear light if there is one.

The easiest way to properly test a dynamo is to connect a 6V 3W incandescent bulb to it.  With a multimeter across the stationary dynamo contacts you should read a few ohms on the resistance range, and on the AC volts range you should read some tens of volts as you spin the wheel.

Realistically, I'd expect a failure of the dynamo itself to cause it to go open circuit with no output whatsoever.

[grams]

This exact thing happened to mine. Returned for warranty replacement with no fuss.

[ElyDave]

Similar issue here, just wired everything up and the dynamo is giving about 8V with the wheel spun by hand, but nothing indicating at the light, no action at all.

The light was good up until March when it came off another bike.  Contacts at the light seem secure.  Likely to be a bad connection at the dynamo (is 8V enough), or the light itself?

[Kim]

Similar issue here, just wired everything up and the dynamo is giving about 8V with the wheel spun by hand, but nothing indicating at the light, no action at all.

The light was good up until March when it came off another bike.  Contacts at the light seem secure.  Likely to be a bad connection at the dynamo (is 8V enough), or the light itself?

Go for a bike ride with it.  The internal battery might be deep-discharged and need to trickle-charge before it comes to life.

I'd expect to achieve more than 8V on an unloaded dynamo with a decent spin.

[ElyDave]

Thanks Kim,

It might be giving more than 8V, but it's kind of difficult to spin the wheel, hold the bike, keep the probes in contact with the wires and look at the meter all at the same time. 

I plan on giving it a run out on Wednesday anyway, so we'll see then

[Kim]

It might be giving more than 8V, but it's kind of difficult to spin the wheel, hold the bike, keep the probes in contact with the wires and look at the meter all at the same time.

If you get it *just* wrong, you can get a spark going between the contacts and zap yourself with it.  DAHIKT.

[grams]

You’re not going to get it up to a representative speed by hand. I find the side of a power drill chuck against the tyre works pretty well, as long as you build up speed gently so it doesn’t slip.

[ElyDave]

Just to be clear here, I have a straight front light, with stand light, not the USB output as well.

Thanks for the tip on speed, it may be as Kim says, discharged stand light battery as well as too slow.. I know that when it was in regular use, it would flicker at walking speed, but that may well have been the stand light battery.

[Kim]

Just to be clear here, I have a straight front light, with stand light, not the USB output as well.

AIUI that one doesn't have a battery in it, so it's probably not a discharged battery (presumably it uses a supercap for the standlight like most lights).

[andrew_s]

Just to be clear here, I have a straight front light, with stand light, not the USB output as well.

In which case it's a Luxos B

[ElyDave]

Right, remade the connections at the hub end - Graeme pointed out some likely issues there - and managed to confirm voles are reaching the other end of the wire and hence the light, 8-ish V on spinning by hand.

Only remains to take it out for a quick spin tomorrow to see if I can get it to fire up, otherwise it's a conversation with B&M.

[ElyDave]

As predicted by Kim, it was just a matter of getting back up to cycling speed and getting the capacitor charged again.

Normal service is resumed and it gives flickery light when trundled and standlight when still, just need to get the alignment right.  All is good for audaxing