Wired bike lights

[anotherkiwi]

I quite like the dynamo lights on my Kalkhoff, they are bright enough to see my way on unlit paths/roads at night and I never have to worry about batteries, even if I get to the end of the motor battery.

The hub dynamo itself is very good and I don't notice the difference. A far cry from the old dynamo lights I had in the 80's with the sprung wheel that pressed on the tyre. That felt like a proper drag when you used it!

If your battery gets to LVC your lights will still work even though there isn't enough juice for the motor. Most DC e-bike lights work from 7v to 42v and the high end up to 60v. The dynamo on the German e-bikes is from the olden times when wired DC lights didn't even exist on the market StVZO have since caught up.

 

[Danidl]

Hmm, you surprise me. I wasn't expecting that. The only thing I dislike more than lighting powered from a separate battery is a dynamo on an electric bike. It's an unnecessarily complex system with unnecessary conversion losses. IMO, not what sustainable transport is about - simplicity and efficiency.

Dare I disagree? The hub dynamo is simplicity itself, a self contained highly reliable unit, needing just two wires to a front bulb and two just more to the rear. Will work for 60+ years. Less drag than from the bottle dynamo sets , which are a friçtion drive and wear the sidewall of the tyres..
An auxiliary battery powered lamp will need to be recharged at irregular intervals.. a recipe for forgetting. And a lighting system linked to the main ebike battery will need a downconvertor, at least as inefficient, and wont work if there is a battery failure.
It is no accident that aeroplanes use turbine generators ,powered by the windspeed for critical electrical services

 

[Deleted member 4366]

I quite like the dynamo lights on my Kalkhoff, they are bright enough to see my way on unlit paths/roads at night and I never have to worry about batteries, even if I get to the end of the motor battery.

The hub dynamo itself is very good and I don't notice the difference. A far cry from the old dynamo lights I had in the 80's with the sprung wheel that pressed on the tyre. That felt like a proper drag when you used it!

You won't notice any difference with the lights switched off, but there is a difference when you switch on. You can't get power out of the dynamo without putting in more than what comes out. That's basic physics. When you are using electric assist, that additional power is coming from your main battery. You take the power out of the main battery to make the motor go, which turns the dynamo and produces electricity for the lights, but less power comes out of the dynamo than what the motor uses to turn it, so you'd be better off connecting lights directly to the battery.

There's a nice article with actual data here. 7.5w is about 10% extra average cycling effort if you were riding unassisted:
https://www.cyclingabout.com/dynamo-hub-drag-lab-testing/

 

[MikelBikel]

Like to have wired lights, the 790 display has a 'Light' switch, but not sure how one hooks up to it, connect a relay on somewhere, i suppose.
Someone suggested just using 3x 12v lights in series on 36v batt.
Or one could hook up the ES suggested modules to it with dc-dc buck, opto relay, etc, to 12v them.
They did have an interesting wrinkle about using a 12v flasher module for always on daylight running blinkers.
Just need to add the darkness + motion auto switch-on and dipping module !
Mikel

 

[Deleted member 4366]

I wouldn't use 12v lights. You should use only LED lights because they're more efficient. If LEDs are listed as 12v, it's because they have a dc/dc converter in them, so you might as well get the ones you want and use your own dc/dc converter.

If you do a search for 12v to 80v LED lights, say on Banggood, you will find ones that you can connect directly to your battery because they have a wide range dc/dc converter inside the light.

 

[MikelBikel]

12-80v lights, thanks d8veh, I'll have a look. Tried Amazon but the sellers didn't deliver to Ireland. So i opted for Nestling 7x cree with separate li-ion, its a pain to keep taking batt off to recharge but v.bright for dark country roads.
Mikel