I saw this: https://www.aaroncake.net/circuits/charger1.htm But I wouldn't mind something a little simpler. I don't need it to be a "smart" charger. I'm fine with having to check the voltage or the battery or something to see if it's charging. I guess what I'm asking for is a circuit that can just charge for like...8 hours or something and charge a 2.2Ah 12v battery and then I unplug it. Can I just use a lm317 and regulate to 14v and run it to the battery?