I use Lenmar Battery Solut

I use Lenmar Battery Solutions replacements, buy mine at Fry’s Electronics for around $70, Model LIC924. It’s a 7.2V 4000 mAh Lithium Ion product. They hold up well and last a reasonable length of recharge cycles. I use them in both my XL1 and GL2 units, and any of the chargers that came with the cameras has worked for me.