This discussion reminds me about something curious tha happened the other day. I have wired my lights into the main loom on my cruiser. It has a n old, geared Q100, and an old, no name controller. The battery was disconnected, and I wheeled it up the drive. The lights came on, so my old controller is making some regeneration from the motor.
Dynamos and hub dynamos, Battery charging
- Thread starter Rod Fuller
- Start date
D
Deleted member 4366
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if you build a regen braking system (flywheels or geared e-brakes), you can do better than off the shelf Shimano 6V 3W dynamo or using the free regen functionality on DD motors .
D
Deleted member 4366
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Why don't you uild one then and tell us well it works. Perhaps you can persuate them to put it on a Woosh bike.
Back to nearly square one, converter & rectification required for battery & lights. RJF
And in any case I have a rear mounted hub motor and at present a Li battery conversion has greater priority than a DD hub motor.
Hi, I'm a newbie!. I've had a P/A bike for about a year now, and am very pleased I bought it (I live in Devon). I use it most days, and usually for longers rides maybe once a week. I have done up to 65 miles, and battery still showing 1/4 charge,. I only use P/A on steep hills, so a lot of the time I am in "neutral", and wondered if I fitted a dynamo hub on the front, I could put a trickle into battery on the flats/downhill sections, for longer rides. I don't mean to fully charge battery!!
Riding an electric bike with an active dynamo on it is the same as riding everywhere with your brakes slightly on. It just doesn't make sense. The dynamos are say 3W. That means that you'd have to pedal 5% harder everywhere you went except when freewheeling. The dynamo would take 133 hrs to fully charge a 400Wh battery, so during a 3 hour ride, you'd save 2% of your battery for all that effort.
What if you had a switch so that the dynamo only operated when you went downhill? Add up all the time you go downhill during a ride. Let's say 15 minutes if you live in a hilly area. That would put 0.2% charge back into your battery, or 0.75 Wh. You could save more electricity by switching off your bike every time you stop at traffic lights or to chat to someone, or even when you're freewheeling downhill. Your ebike electrical system draws about 3W when on standby (switched on but not assisting).
I say it again: It doesn't make any sense to use a battery to drive a motor that drives a wheel that drives a dynamo that makes electricity to put back in the battery because you never get back what you started with.
What if you had a switch so that the dynamo only operated when you went downhill? Add up all the time you go downhill during a ride. Let's say 15 minutes if you live in a hilly area. That would put 0.2% charge back into your battery, or 0.75 Wh. You could save more electricity by switching off your bike every time you stop at traffic lights or to chat to someone, or even when you're freewheeling downhill. Your ebike electrical system draws about 3W when on standby (switched on but not assisting).
I say it again: It doesn't make any sense to use a battery to drive a motor that drives a wheel that drives a dynamo that makes electricity to put back in the battery because you never get back what you started with.
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Hi vfr400, (I have a Benelli Tornado, but I digress!!). Many thanks for your post, I didn't realise that dynamos cause that much drag, DOH! So when I switch off display on long flatish or in towns (which I do now), that saves as much as dynamo would put in, plus it would be harder on those sections, and presumably up hills as well!! Can you switch the dynamos off (the hub type I mean)? I didn't think you could.
All in all I think I'd better give up on that idea, thanks again for your help, Jerry.
All in all I think I'd better give up on that idea, thanks again for your help, Jerry.
It certainly does not not make efficiency sense as you say. It arguably makes reliability sense; if you run out of battery on the way home you still have light. A couple of rechargable USB lights probably makes more sense though.
I have wondered what the logic is in having electric bike lights powered by a dynamo, when there is a battery on board? My wife's Kalkhoff Agattu being a case.
All I can think is safety for getting home in the dark after flattening the battery.
All I can think is safety for getting home in the dark after flattening the battery.
