OK,

So what you really want is a SLA battery charge circuit driven from a solar panel. Why didn't you say so?

Now, I'm no battery expert, but from what I understand, (sealed) lead acid batteries are happiest either with constant current charging or trickle charging.

Most voltage regulators are just that - voltage regulators, not current regulators. I'd suggest you check out specialist battery charge circuits from manufacturers like Maxim or maybe Analog Devices.

Also, you mentioned your battery was a 6V battery - that's a little uncommon where I come from (Australia) for SLAs. Over here we have a retailer (Jaycar - www.jaycar.com.au) who have a range of PV regulators for 12V SLA batteries which is what is more commonly used (along with 24V).

Regards
Phil.