B&M Toplight View Plus Rear Light: standlight fault or overexcited dynamo?

[mr ben]

I bought a rack-mounted B&M Toplight View Plus earlier this year and the light worked fine when moving but the standlight didn't.  SJS sent me a replacement which worked properly for about 900 km but then developed the same fault.

I have a B&M Cyo N Plus front light.  Wiring is hub to front light, front light to rear.  Previously it all worked fine with a mudguard-mounted B&M 4D-Lite Plus.

I have two wheels, one with a SONdelux and the other a Shimano DH-3N80 hub; I've checked the Toplight with both hubs and tried swapping the connectors around at hub and light and in all configurations the light works, but only when moving.  I've gone back to the 4D-Lite for a test around the block with both hubs, and its standlight is working fine in both cases.

The very helpful Ed at SJS has been in touch with B&M and they've said the only reason this would happen is if there is too much power going to the rear light causing an overload and blowing the capacitor.  He also says from my description I have it wired up correctly so it's not clear what the problem is.

I took the first Toplight apart to see if the capacitor was loose but it seems well attached.  Now, I *think* that both times the Toplights have failed was on their first meeting with the SON hub, but I can't be sure because my spreadsheet isn't quite that detailed.   So it seems like either there is a dodgy batch of lights - but nether SJS or B&M are aware of this.  Or there is a problem in the set-up with my SON, which has quite happily run the 4D-Lite for 5 years without a problem.

Any ideas from the hive mind?

[fuaran]

I also have a Toplight View Plus with a standlight that has stopped working. It rattles when I shake it, so I suspect the capacitor is loose. I've not tried taking it apart yet, not sure if that is possible without breaking it completely.

Anyway I have now ordered a Toplight 2C to replace it. I'll see how long that lasts.

[Kim]

I also have a Toplight View Plus with a standlight that has stopped working. It rattles when I shake it, so I suspect the capacitor is loose.

My bet is a bad spot-weld on the supercapacitor legs.  I've encountered this before on Spanninga Pixeos, and preempted it on my Brompton rear light (which is known to suffer this failure mode) by mechanical reinforcement with hot glue.  You'd think the lead-free solder joint would go first, but apparently not.

Of course, both of those are easily dismantlable with a screwdriver...


Either that or the OP has some exotic fault with the front light, subjecting the rear to the full power of the dynamo for prolonged periods (which apparently they aren't usually rated for).

[jsabine]

I've found that my Toplight Line Plus appears to be polarity-sensitive when connected to my Luxos U - one way round it works only when moving, but the other brings the standlight into action.

(Yes, that's a different rear light, a different front light, and a configuration change you've tested without success - do I get a full house for unhelpfulness?)

[mr ben]

Thanks folks.

I also have a Toplight View Plus with a standlight that has stopped working. It rattles when I shake it, so I suspect the capacitor is loose. I've not tried taking it apart yet, not sure if that is possible without breaking it completely.

Not exactly; I managed to prise the front and back apart with a tiny screwdriver very slowly without actually breaking anything, but it would need to be glued back together.  So no I wouldn't say 'easily dismantle-able', especially if you want to re-mantle it afterwards.

Either that or the OP has some exotic fault with the front light, subjecting the rear to the full power of the dynamo for prolonged periods (which apparently they aren't usually rated for).

Hmm, I never thought of that.  I hope not otherwise this is going to get complicated.

...do I get a full house for unhelpfulness?

  No, I'm glad to hear I wasn't being daft checking the polarity!