No, I didn't check for noise. But since the Tekeon battery puts out what is apparently a flat, steady voltage almost until it collapses, I'd rather make that test with a Gel-Cell battery whose output declines steadily.
Next weekend, if I have time I'll try that and let you know what I find. I have seen (actually, heard) that happen with the Denecke AD-20, so I agree that it's worth checking out.
--best regards