The charging/lighting setups of these vintage machines are crude and kinda half-assed, at best. When everything is new and within spec, it worked...well enough...sorta. The head lighting was never good, battery life was often short due to overcharging, and it didn't take much to cause an instant, cascading, failure. One broken filament, or an unexpectedly cooked battery, and the rest of the bulbs would burn. Turn signals are (in)famous for
up if any value in the system changes. The problem, IMO, is the "voltage regulation"...it's about as refined as surgery was, circa 1850. It was "alright" for lead-acid batteries, as long as you don't mind frequent replacements. The failures weren't dramatic.
Lithium-ion batteries are a whole other world. The vastly increased charge density that we want comes at a price...basic physics. Pack enough electrical, chemical, or electrochemical energy into a small space and you have a potentially incendiary situation, should that energy be suddenly, uncontrollably, released. And commercially-available Li-ion batteries, when they short-out, are prone toward cascading failures...that can melt metal. With state-of-the-art charge regulation, i.e. floating charge rate, it works pretty well...mostly. CT70-era charging circuitry with a Li-ion battery is, imho, tantamount to performing brain surgery with a ripsaw. :butcher: If one were to upgrade the charging circuitry of a vintage system, they'd have a fighting chance...maybe.
There is one basic issue that won't go away. These little bikes are a hostile environment for something as sensitive as a 2017 lithium-ion battery...wide temperature swings and vibration[SUP]3[/SUP] Battery technology is rapidly maturing. Doubtless, we will see Li-ion batteries that are virtually failsafe...in 5 to 10 years. I expect the marketing curve to resemble what we've seen, thus far, with LED technology. And that has reached the steep section of the development curve. They've gone from mediocre and hideously expensive to very good and, while still not cheap, at least reasonable value for the money.
I'm with JP & jdm...too much of a gamble, at this time. For the same money, you can buy 4, or 5, SLA batteries and toss `em like Dixie cups, if need be. Now, in the interest of providing full disclosure, my approach is decidedly conservative, i.e. stick with what works and wait for some real world field service history to become part of the landscape, especially when there are known problems. The arse that doesn't get barbecued might be your own...
