Thorn Cycles Forum

Technical => Lighting and Electronics => Battery Charging from a Dynamo => Topic started by: Andre Jute on July 30, 2014, 09:07:46 AM

Title: A systems approach to battery charging for on-bike devices
Post by: Andre Jute on July 30, 2014, 09:07:46 AM
[Dan, when you eventually get back on the job, you may want to make a child board for electrified bikes, as this thread doesn't quite fit the child board headings that now seem a bit narrower than they did when created.]

When I fitted an electric motor to my bike, I thought that the irritation-factor of recharging the battery would be a consideration, as it had been for heavy-duty battery lamps years ago, but I just turned it into part of the routine. I routinely unlock the battery from the bike, unplug it, carry it up to my study with the rest of the stuff that goes to my study, and plug it in immediately. Before I go to bed a quick glance around my study (while my computer shuts down) tells me whether any battery charger lights are on and what colour they are, and then I pull the plugs. As an event of your day, it's an irritation; when you turn it into a habit it consumes a few hardly noticed seconds. I've turned the batteries in other devices into the same routine. When I sit down at my desk, I plug in my iPhone, when I go to bed I plug in my iPad.

All these things have in common that they're easily and quickly removed from the bike, pockets or bags, whatever they're on or in, and easily plugged and unplugged, and come with internal battery health controls. The bike battery for instance unlocks with a key on the ring that I already have in my hand at that point from unlocking the n'lock to secure the bike, and the output plug for the battery is an aircraft type bayonet with a quicktwist lock which, the way I have it rigged up, doesn't actually need to be done up, though I do fasten it because it never cross-threads and takes only a fraction of a second, literally, once it is a habit. The iPhone and iPad are charged through a buffer battery scaled to run out of juice before their 12-hour overcharge limits are breached; the same buffer battery goes on my bike to recharge the iPhone (which operates my heart rate monitor) or, theoretically (since the thing has never actually run out of juice), the Kodak Zx1 bike camera, on very long rides, undertaken at most once or twice a year (last year only once, this year not yet, though in the present fine weather I have hopes). I could recharge all these devices from the main battery, but it would mean fiddly wires being plugged and unplugged; the buffer battery weighs six ounces, goes in the bar bag together with a custom cable I soldered up in ten minutes with plugs for all my devices, and works very conveniently. On my desk the buffer battery is permanently plugged into a charger to recharge it; it's cheap enough to replace once every year or two if I should overheat it (no sign of it getting hot).

But wing nuts, fiddly little clips, attachment modules that have to be rotated around the handlebars to get them off, stuff that take time and attention, I don't want to know about. All of that stuff, no matter how useful or how long between battery changes/charges, is now gone from my bike. The iPhone slips into a see-through, work-through waterproof bag on the handlebars, no zip even, the iPad goes into a saddlebag (very rarely actually), the vidcam is on a tiny plastic tripod quick release headthat clicks in to a fitting permanently on the bike that also holds my pochade box (a painting box).

A systems approach beats ad hoc chaos every day