So, I've got an old 6v Vistalite light body, cables, and a dead, disassembled 4 C-Cell nightstick that I want to repurpose as a 12v, 15-20 watt backup light.

• Can I assemble a new battery array of 8 rechargeable C-cells and hope to charge it with the original wall wart recharger, or do I need a different charger?
• Do I need more than 8 cells? I generally see 12 volt systems rated around 13.7v, or so, it seems. Or is it because rechargeables are rated lower?
• This seems pretty easy and straightforward... what am I forgetting?