After blinking away all day I'm certain my tail light is fine, I just have a batch of defective Rayovac batteries. The packaging has this big guarantee plastered all over it. But upon looking at the details it would probably end up costing me at least as much as package of batteries to collect on it. That is if I actually had the receipt. Who actually keeps receipts for stuff like that.

I've never had bad batteries before, considering Rayovacs aren't that much cheaper than Duracell / Energizer I guess I'll stick with those brands.