What's that battery maintainer doing?

[scd]

I think winter is freezing my brain. I'm contemplating stupid stuff. I've got a Die Hard battery maintainer on the '68 HD with conventional battery. I notice the charging light come on every few minutes for a second. I put my voltmeter on the battery and see that the maintainer is putting a load on the battery, draws it down to 13.25 volts, then runs it up to 15, and keeps repeating. I guess this it to keep things happy in there, but wonder if all that charging/discharging is fine. I can hear hydrogen bubble. I have only had to top it off once though in the last year, so must not be boiling too bad. Anyway, I know, I need to get a life, if only the weather would cooperative. Thanks, steve

[Dana]

I have no idea. For the winter, I take my battery out and keep it in the basement, off the floor. Then recharge it in the spring. Seems to be okay.