Hello, I am wondering for those who've used this light, can it only be charged using the proprietary 2600 mAh battery it comes with via USB? The battery has a plastic ring around the button top and doesn't make contact in a D4 charger. Can I use a 3400 mAh 18650 in it instead? How would that affect performance and run time? Is it safe to use the higher mAh battery?