Theo Markettos said:
I presume I'd have to knock up my own 6V battery box for the time
being, or do such exist for driving normally-dynamo lights from
batteries?
I used dynamo lights driven from a battery pack for several years.
I used a number of battery solutions.
A box that took standard cells has most flexibility for when you're
out-and-about and your rechargeables expire - simply remove
rechargeables and insert non-rechargeables bought from some local
source. Alternatively, you can keep a pack of non-rechargeables with
a five year shelf-life as backups.
A 6V lead-acid looks tempting. However, I never had very good life
out of them. You need to source one with deep-drain life, and these
tend to be in large sizes (eg golf-cart / ride-on electric buggy).
The ones in the size you want are more likely to be fire-alarm type
expecting to sit on trickle forever and once in a blue moon discharge
a little bit if there's a power cut. Also, the ones in a size you
want seem to be not wildly tolerant of vibration. I didn't get
terrific life from them - they died completely more often than I
wanted.
The best solution was using radio-control car NiCd packs. These are 6
cells, so nominal 7.2V, so quite a high over-voltage. I had no
problems (blew bulbs less often than the same bulbs on an actual
bottle dynamo), but you might want to be a bit cautious with modern
cleverer LED lights and the like.
The advantage of these packs:
1: They're next-thing to indestructible. Life on a bike is much
easier for them than their intended life in a toy car where they might
be called on to provide 35A or more, subject to horrible vibration and
general abuse.
2: the capacity is nice (1-2Ahr gives you several hours light from a
2.4 W bulb).
3: The connectors they come with as standard are tough,
indestructible, polarised, latching and chunky enough to work with
gloves. You can buy the mating connectors for your bike wiring loom
from model shops. (You can wire a standard 4-cell-AA battery box to
the same connector to give you an emergency spare pack).
4: The pack physical size is both reasonably easy to fit on a bike
(mine strapped across the pannier rack with a velcro strap) and
standard (so when you buy another pack, it will fit in the same place
with the same fixings).
You will need a specific charger you probably don't have already
(unless you play with RC cars, or have some other charger that will
do six cells).
In theory, you could make up a 5-cell pack from the same cells
(www.overlander.co.uk cell inidividual cells, as will a decent model
shop). However, as noted, I never had problems with 7.2V and buying
ready-assembled standard packs is easier.
regards, Ian SMith
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