Dynamos and hills - battery backup?

[pete75]

Tried my 3 bikes equipped with dynamo lights and the little Axa Pico 30 lux produces a good beam with not much flicker straight away at walking pace.
What would improve your light output at low speed is to switch to a battery back light so all dynamo power is going to the front light.

[[XAP]Bob]

Tried my 3 bikes equipped with dynamo lights and the little Axa Pico 30 lux produces a good beam with not much flicker straight away at walking pace.
What would improve your light output at low speed is to switch to a battery back light so all dynamo power is going to the front light.

Not hugely though - the smaller lights don't require the full 2.4W anyway.

[mercalia]

the smaller lights don't require the full 2.4W anyway.

I can believe that. Withmy bottle dyno I seem to get full brightness at about 9mph or less. It would be interesting to try a budget dyno ( those really cheapo ones ) with the Axa Pico30 and see how it goes. As I said before I think the need for powerhouses like the BM dynotec S6 is probably over kill for such modest but brilliant lights?

[pete75]

Tried my 3 bikes equipped with dynamo lights and the little Axa Pico 30 lux produces a good beam with not much flicker straight away at walking pace.
What would improve your light output at low speed is to switch to a battery back light so all dynamo power is going to the front light.

Not hugely though - the smaller lights don't require the full 2.4W anyway.

It seems like the OP is using bulb not led lights. Front will want 2.5 watts , rear .5 from a dynamo that produces 3w. Going to a battery back light should make a reasonable difference at the low speeds he's talking about when the dynamo is producing less than 3 watts and the back light is drawing almost 17% of that output.

[[XAP]Bob]

Ah, yes - switching that out rather than the front light...

[pete75]

Ah, yes - switching that out rather than the front light...

Well it's seems worth a try if he's happy with the usual light output. LED lights seem so much better now but the old halogens certainly gave enough light to ride with on unlit roads. Mind you I thought the old metal Ever Ready front lights were good - younger eyes then though.

[edocaster]

'Town & Country halogen' would be pretty obsolete, judging by http://www.buechel-online.com/en/produc ... pandable=0 - 10 lux at 10 metres just won't cut it nowadays. Modern LEDs are several times more efficient, and that means the standlights are likely to be brighter too (as most of these lights use the same 1 or 1.5 farad capacitors for standlights, and need to light for about 4 minutes, so the rate of discharge won't vary much - but LEDs are far more efficient in this like for like comparison).

Dynamo light technology changes a lot. Wheels don't. I'd say definitely keep the wheel.

Theoretically, there's nothing wrong with using capacitor standlights in the situation initially outlined. For example, if two lights with standlights which could be disabled (e.g. B&M Cyo) were used in parallel or series, both could be charged up and switched off (i.e. storing the charge) from a previous ride. Then, on starting this ride with the hellish climb, one light could be switched on, with the standlight being fresh. Then, a few minutes in, the second light could be switched on. In other words, there's no limit to the number of capacitors which could be switched in, simultaneously or sequentially. Light makers just don't make a product for this.

For getting drivers to dip... that's another issue. The standlights on most German-legal dynamo lights are just dimmer versions of the main light. Because they are limited to 2 lux at 10 metres distance for the beam above the cutoff when operating in full mode (i.e. nowhere near a high beam anyway), in standlight mode you can expect an entire magnitude less light going to the eyes of drivers. Not being able to control the angle of the light quickly means you just have to live with this.

[mercalia]

the halogen better than the old Ever Ready jokes. I cant believe now things were that feeble? But then I still remember( just) when some street lights were still gas and had mantles lol. But my BM halogen is (not quite so ) feeble compared to the cheap Axa pico30 led.

[cotswolds]

It seems like the OP is using bulb not led lights. Front will want 2.5 watts , rear .5 from a dynamo that produces 3w. Going to a battery back light should make a reasonable difference at the low speeds he's talking about when the dynamo is producing less than 3 watts and the back light is drawing almost 17% of that output.

The back light is LED so I doubt switching it off would make much difference, but the question is academic as it doesn't have a separate switch.

[pete75]

It seems like the OP is using bulb not led lights. Front will want 2.5 watts , rear .5 from a dynamo that produces 3w. Going to a battery back light should make a reasonable difference at the low speeds he's talking about when the dynamo is producing less than 3 watts and the back light is drawing almost 17% of that output.

The back light is LED so I doubt switching it off would make much difference, but the question is academic as it doesn't have a separate switch.

It's my guess it has wires going to it which could be disconnected.

[squeaker]

Something like this one reviewed here?
(I have no experience with this light - just happened on the ongoing review.)
HTH

[MikeF]

Something like this one reviewed here?
(I have no experience with this light - just happened on the ongoing review.)
HTH

I have (somewhere, but I can't find it!) a light that has (rechargeable?) batteries and is driven from a BB "dynamo". It's of late 1980s vintage so it doesn't have a LED. At low speeds the light is battery driven and at higher speeds "dynamo" driven. However it gave a good light for unlit roads. This is the sort of light the OP needs, but technology seems to have moved on. Anyone else used one?

[andrew_s]

Sounds like what I remember as the "Byka Owl".
Removable handlebar mount, cylindrical, maybe 2" diameter x 5" long, contained 4xAAs, and ran off either them or a 3.8W Sanyo BB dynamo according to speed. I don't think it charged the batteries, but as the light mostly ran off the dynamo, they lasted well. I also may have one somewhere - I remember cannibalising the handlebar mount when I was making DIY LED lights, pre Solidlights.

[foxyrider]

the little Axa Pico 30 lux produces a good beam with not much flicker straight away at walking pace.

Can say the same about mine but the dynamo output is the key thing, my SP8 is very good at lower speeds and about two minutes riding will charge the Pico's standlight.

Never heard of this '3mph', is it a special code of some sort?

[MikeF]

Sounds like what I remember as the "Byka Owl".
Removable handlebar mount, cylindrical, maybe 2" diameter x 5" long, contained 4xAAs, and ran off either them or a 3.8W Sanyo BB dynamo according to speed. I don't think it charged the batteries, but as the light mostly ran off the dynamo, they lasted well. I also may have one somewhere - I remember cannibalising the handlebar mount when I was making DIY LED lights, pre Solidlights.

Yes. That sounds like it or something very similar. Possibly was Byka model.