Dynamo hubs for lighting

[Mundo]

Is anyone using a dynamo hub for lighting on their E-Bike?

Any issues at the higher speeds?

Many dynamo hubs are 6 vdc 3 watts.... will these volts and watts increase at higher speeds?

I'll be trying a dynamo hub in a 26" wheel at 25 mph.
Light bulbs (Head & Tail) will be 6 volt Halogen. 2.4 watt.

Thanks for any information.\

http://en.wikipedia.org/wiki/Hub_dynamo

 

[cycborg]

Back in the old days high speeds could blow out unprotected incandescent headlights, but nowadays the lights almost all have regulated LED circuits so there’s no problem even at speeds well above 25 MPH. I have this setup on my non-e-commuter and while I rarely reach 25 MPH, I frequently exceed this on downhills and my light has lasted for years now without any problems.

That said, on an ebike you can bypass the complexity, weight, and inefficiency of a dynohub and just run a DC/DC convertor from your main battery. Many threads on appropriate lights and converters on here.

 

[Drunkskunk]

Sort of pointless on an ebike. At best it's a pretty good loss of efficiency for the power they put out. All they are doing is stealing some of the motor's power through a really inefficient means, and converting your battery power back into electricity at a huge loss. And they don't put out much power, either.
Typically under 5 watts. It's also a waste of weight, as they are heavy for the job they do.

Might be useful for a non motored bike, but with such a low output, you aren't going to get very bright lights.

 

[dogman dan]

Better to just get a good led light, powered by the bikes battery or a separate battery. The led's don't chew through batteries like incandescent, so even something run on rechargeable AA's works fine.

 

[samsavvas]

Is anyone using a dynamo hub for lighting on their E-Bike?

Any issues at the higher speeds?

Many dynamo hubs are 6 vdc 3 watts.... will these volts and watts increase at higher speeds?

I'll be trying a dynamo hub in a 26" wheel at 25 mph.
Light bulbs (Head & Tail) will be 6 volt Halogen. 2.4 watt.

Thanks for any information.\

http://en.wikipedia.org/wiki/Hub_dynamo

There is unfortunately a lot of misinformed opinion around about dynamo lighting systems (I think I'm being quite polite about this BTW!) I have a couple of commuter e-bikes. Both had Shimano front dynamos prior to conversions and I've left the dymano wheels on the bikes. They worked splendidly before e-bike conversion and continue to do so! Most of my other bikes run dynamo systems and have done so with complete reliability and satisfaction for many years.

Wheel dynamos these days:
- are very efficient (read the CTC evaluation by Chris Juden)
- are matched by truly excellent, focussed lights based on what are know as 'power LEDs (you can usually 'mix and match' across brands according to your preferences)
- can easily(!) run a bright rear light and 1 or 2 front lights.

I understand that a bicycle wheel dynamo is what is known as an 'inductance load' in a circuit. With increasing revolutions current output will increase to the point where the rotating coils saturate and then this increase stops at a point that is fortunately the optimal current level for a modern power LED! There is therefore no danger of over-powering the lights in a modern power LED-based lighting system! 'Over-volting' - a problem with the old incandescent front bulbs is no longer relevant as LEDs are current devices. The LEDs last - more or less - indefinitely. They also take no significant power from either the cyclist's legs nor from a battery and provide excellent redundant capacity. It's no fun pedalling home with a flat battery and no lights! Not that it happens often of course but I like the principal of the thing, knowing it won't happen to me.

If you are not interested in such a principal you can of course run regular headlights and tail lights, powered by internal batteries or directly from the e-bike's battery. Phillips and (I think B&M) make outstanding front lights for e-bikes which are connected directly to the bike's main battery (voltage more or less immaterial). I have this Phillips light on a 3rd e-bike. It's twin LEDs are rated to 60 or 80 lumens with a shaped beam which is extremely effective. On the road you'd never want more light than this provides (think 'car headlight'). But I like the simplicity and redundancy of the dynamo system...

If you are still running a halogen light you are not really working with a light that is optimised for a dynamo system. An halogen (incandescent) bulb is not a current device and so will not be inherently self-limiting like an LED light. You'll need a simple zener diode in the circuit to limit the voltage going to the bulb as speed increases. Virtually all decent halogen systems had at least some form of zener-based limiting built in already so you shouldn't have problems at speed. Some (like the SON E3) indeed had more sophisticated systems. There's plenty of advice on-line.

However if you are interested in running a dynamo system on your e-bike I suggest you look into a cheap set of well designed dynamo lights. Dosun make an excellent system that is available on-line at a very reasonable price and that rivals the SON, B&M and Phillips products in quality and construction. And there are heaps of cheap plastic-bodied European dynamo light sets available on the net that have excellent, shaped beams and blow even the excellent SON E3 halogen light off the road!

Savvas.

 

[d8veh]

There's absolutely no point in fitting a dynamo. It's the same as putting a second motor in your front wheel to recharge your battery while you're going along powered by the back motor.

It doesn't make any sense to use the electricity from a battery to drive a motor that drives a dynamo to make electricuty that you already had, especially when you get back less than what you started with.

Get alight that runs directly from the battery, like the Banggood ones, or use one of those Cree T6 ones that have a 4-cell rechargeable battery pack.