Mechman actually said there was nothing he could do reduce the voltage - he could only turn it up, for whatever reason. He might have meant "nothing I can do without rebuilding your alt", which is essentially what I was asking.
What I am really curious about is finding the spec sheet for the 66160 Yinlong cells XS sells, mostly out of curiosity. Might have to e-mail the Chinese distributor that
@hispls used for his big order. I don't doubt that you and spls have the specs correct for the cells he's already got.