maybe check the altinator ?

 

Could still be a weak battery. Even once you run it around a bit to charge it up, it may stay weak, especially if it's a few years old anyway or if the headlight incident ran you down to absolute zero. In the worst case, could have ruined a cell in the batt. To charge the battery as good as possible may take a good 40 minutes on the highway or more. It won't charge much, if at all, at idle. There are a lot of really boring (for non EE people) reasons why that's so, but the long and short of it is that auto batteries are not meant for deep-cycling and never recover very well from it. For why the turn signal problem would go with this is that on most cars with a few last-ten-years solid-state exeptions, turn signals run on some pretty decent capacitors. Charging those actually takes a fair amount of power, and if the battery is now sub-par it's not going to power that circuit very well or consistently. Solution: new battery, especially if you have any warranty left on the old one, as they're usually pro-rated for time. Other fun with capacitors: if you know anyone who does the annoying play-with-things-on-your-desk/workbench behavior when they talk to you, leave a charged capacitor sitting out. Sooner or later they'll touch both leads (completing the circuit)and get a hell of a zap out of it. I wouldn't advise this if they're heart patients or pre-disposed to legal action, though!