Paul__B: A SLA battery charger. See his other thread.
Aha, thanks for that. I do strive to know what I don't know, and I can say that I am pretty much ignorant of battery charging algorithms. In general maybe there is a constant current phase for most of the charge but then this tapers off and/or switches to a trickle mode to keep things topped off, but details matter as does battery chemistry. Interesting stuff actually, I should educate myself a bit sometime. So I might look for an IC built for the purpose, although I always understand the attraction of rolling your own.
That said, I'll probably sit the rest of this one out, other than reiterating that before actually attempting to charge any batteries, the OP should Google up some tutorials and ensure they have a very solid understanding of Ohm's Law and also power relationships. Burning up a resistor may smell bad but failure of a lead acid battery could be quite a bit less enjoyable.