Jon what 18650 batt you got mate ?
I've got 2 Tracer 2600mah ones that came with the Ledray torch. I've got no idea how old they are - I bought it used a couple of years ago.
I got the UniqueFire 3600mah ones with an NVUK kit about a year ago. These went tits up after about 6 months.
The ones arriving today are described as 'Geneneric BRC 18650 4000mah rechargeables'. The reviews on them were good so, I thought I'd give them a punt.
They can't be any worse than the ones I've got now ...... fingers crossed