I believe it is the exact same driver. I’m looking at them both right now, and the markings and layout are exactly the same. The Astrolux C8 even has “BLF” inscribed on the board, just like the BLF A6.
Yes, if you can reprogram it, I’d definitely increase the step-down to 2 or 3 minutes.
Oh, I see. Well, the only modes you can really compare them are the medium and lower modes, since they both use 7135 chips at that level. However, they don’t have any brightness modes the same.
On higher modes, they’re also very difficult to compare, because both lose output as the battery drains, but at different rates.
If I understand the 7135 chip, it will draw 350mA (so 2800mA for 8 of them) at a constant rate until the voltage drops low enough that they can no longer supply a constant current to the LED. Unfortunately for the Convoy with 8 of these chips, this seems to happen fairly quickly. I don’t have a Convoy with less than 8 chips (I never really understood the benefit of it), but it may give a much longer regulation time with 4 or 6 chips instead. In a perfect world, the Convoy would draw 2800mA until it dies, but the world is not perfect.
A FET driver will just suck as much power from the battery that the LED can take. As the battery voltage drops, it supplies less current to the LED.
You’re right that a FET driver doesn’t “waste” any power (like the 7135 does with excess voltage). However, the LED is much less efficient at the high current that is supplied to it. So, you’ll get less run-time with a FET at the same brightness (if you could maintain that brightness), because the LED is being over-driven (and brightness controlled by high frequency PWM).
I’m not sure if I’m making sense, but hopefully it makes some sense. And I’m probably missing some points that others can expand on.