Bright Lights All Night?
(3 approaches to brighter lighting)
 High-Wattage bulbs and the LVR2
  Twin Headlights with a generator
   Three Micros with Lithium power
With grateful acknowledgement to the denizens of the Bikecurrent mailing list,
whose ideas have contributed so much to these articles. 
Bikecurrent Archive




Bright Lights All Night?
by Francis Cooke
Is it possible to use battery lighting and cycle all night with bright lights?

Well of course it is possible, but how practical it is depends on what we mean by 'bright', and what we mean by 'all night'. This article sets out some thoughts about what really, in all honesty, constitutes 'all night' for the majority of night-riders.

Let us say, as a starting point, that we want to ride through an 8 hour night. (Although midsummer nights are much shorter than this, riders looking to Paris-Brest-Paris, for example, will be facing nights that are longer, more like 10 hours.)

What do we mean by 'bright lights'? With modern high-brightness systems offering 16 watts or more, a reasonable minimum might be considered to be 6 Watts, as 6V 6W halogen bulbs are fairly readily available.
These bulbs draw 1 Amp so a 6V battery packing 8Ah is required.

8 D cell Alkaline batteries (eg Duracell) would in theory do this, weighing 1120g and costing about £12 in the UK, to be thrown away at the end of the night. In actual fact the light from such a system is remarkably poor, due to the inadequate current-handling ability of Alkaline cells, but there is a high-tech way round this using a Willie Hunt Lighting Voltage Regulator (or LVR2) which gives good results.
Regulator or not, many people would find this rather expensive and environmentally suspect, and it is more usual to find lights of 6W and above run off rechargable systems.
Sealed Lead-Acid batteries are a popular choice, and Yuasa offer a 6V 7Ah model which weighs 1280g and costs £16 or a 10Ah model (surely over the top?) which weighs 2000g and costs £17.50. The additional expense (to which must be added the cost of a charger) would rapidly be recouped compared with Alkalines. What is more the lower internal resistance of these batteries will result in a much better, brighter light than the Alkalines can achieve.
However, the rider who is going to ride through an 8-hour night will almost certainly be riding at least 12 hours in daylight as well, which means lugging a battery the size and weight of a house-brick around all day. I think this is too big a price to pay for being able to cycle all night with bright lights.
Good quality NiCads offer more power for less weight, and in fact battery technology has come on quite a bit, and it is now possible to buy much lighter rechargable batteries, using Lithium Ion or Nickel Metal Hydride chemistry. They are much more expensive, and rather less robust than SLAs or NiCads from the point of view of storage and recharging. But, for instance, 10x 4Ah NiMH cells would give the required 6V 8Ah capacity, weighing just 600g and costing around £60. Once again, plus the cost of a charger.

One way or another, you carry a lot of weight or you pay through the nose. This is why most cyclists have always put up with a much dimmer light (around 1.5W) in exchange for being able to carry a much smaller and lighter battery.
Let us take another approach to weight reduction, by re-assessing our 8-hour night.


The advent of front LED lights is changing all this quite dramatically.
(Note that if, like some people, you are seriously opposed to front LEDs, you still can follow this logic by substituting, instead, a second front light of very low Wattage).
Let us look again at our 8-hour night. There are times, such as dusk and dawn, when the cyclist needs very much to be highly visible, but the LED lights front and rear will cope with this requirement quite well enough. With LEDs on during these times, the cyclist does not need a bright driving light to see by.

So, from our 8-hour night, knock off 45 minutes each for dusk and dawn.
Most cyclists will make at least one stop during a night ride, knock off another 45 minutes. Of the remainder of the night, probably half (in British conditions) will be ridden on lit roads. We are now down to less than 3 hours.
We now only need to carry 3Ah of battery for our 6W light.

SLA users have a choice, from Yuasa, of 2.8Ah weighing 560g or 4Ah weighing 850g. The former will be good if you ride on lit roads for at least 50% of the time, but go for the latter if you ride mostly on unlit roads. Other manufacturers might supply the much-needed intermediate size, for instance I have a Panasonic 3.4Ah battery (stripped out of a rechargable lantern) which weighs 590g and is exactly right for most night rides in the UK.
A pack made up of 5x 4Ah NiMH cells weighs in at a mere 300g with capacity to spare. On a summer night, you might even be able to use this with a 10W bulb.


Incidentally the Scott Dickson dodge of using two smaller independent battery systems and switching between them regularly is an excellent way of getting the most out of batteries - they really do recover noticeably during the rest period.
And of course switching your main light off whenever possible on lit roads achieves the same thing.

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