I’ve been riding everyday through the floods which have submerged my SP hub dynamo and you know what. It worked flawlessly. The front light didn’t flicker at all. I’ve had the dynamo for 6 days short of the two years mark and have completed over 9000 miles on it (thanks Strava) but the bearings have taken a hammering. Despite the internals working the bearings have needed to be replaced which I can’t do since I’ll destroy the dynamo, it needs recalibrating. So luckily for me there’s a two year warranty on these things so it’s been sent off to Taiwan to have the bearings replaced for free although it costs £7.20 to send it out there. If they weren’t within warranty it would cost $30(inc. p&p) for the repair plus the £7.20 cost to send it out there. I think that’s pretty damn good. I do wish they were user serviceable but they’re not and the cost to get it good again is fairly small. Everything needs servicing at some point and SKF bearings can cost £11 each anyway.
It took me half an hour to strip the dynamo out of the wheel and I do have a back up spare wheel. The one I had before I built up my dynamo wheel.
The main inconvenience is in having to make sure my front and rear lights are charged without the reassurance of my ultra reliable dynamo lights.
Anyway just wanted to say dynamos are great and I can’t wait to have it back.

I’ve been thinking about one of these hubs and I’d seen the comments about bearing not being user-serviceable – which worried me somewhat. Your tale makes me feel a bit more positive about them. I reckon the new 15mm axle version could be just what I “need”.

What type of Dynamo is it?

Fantastic things. I wonder if you could grease-guard them?

It’s a Shutter Precision Dynamo. The one I’ve sent back is the PV-8 but I am building a new bike with a black PD-8X which looks excellent.
I really want dynamo technology to develop and would love it if the current they output was increased. Charging my phone off the dynamo shows that it’s getting the usual USB output of around 450mA. The higher the current the quicker it’ll charge.
I didn’t protect my dynamo at all and cycled through floods which literally submerged the dynamo over a stretch of say 30 odd meters and a speed of around 8 mph. There’s increased water pressure at that speed which would force the water past the seals. Not a way to treat my bike but a really good test!

How about a hub dyno, regenerative braking, and e-bike? Has it been done yet?

SON hub here still going without any maintenance for 8 years on a an all year round commuter. 6 of those years have been off road commuting.