Join Date: Dec 2009
Location: Montpellier, , France
Like Colin, I still use regular AGM batteries in my bikes, my SSD included. Quality AGMs push out the CCA you need and you should expect 8+ years of life. I can't really see the advantage of Lithiums: they're more expensive, are reputed to be fussy about how they're charged - and the weight saving sure ain't gonna make no difference!
That said, I know at least one Laverda owner who's running a Lithium in his late 1990's bike. He seems happy :-))
But back to your questions: voltage spikes. Well, not so much 'spikes'; but the standard reg/rec in these bikes is a fairly simple bridge rectifier and shunt regulator and yes, you can see voltage at the battery going up to 14v or so. A more modern Mosfet would deal with this - but it's yet more expense to deal with a problem that you've caused in the first place. So ...
As to the charge current. In theory, the alternator can put out 200 watts at a rectified 12v. Which in theory could push the current above 16 amps. In practice? Not so sure ... :-)