Future project proposal: the A-family

Commercial Sellers' Spot
2

Rationale

Some A-family features are not obvious. Some are not commonly liked. I’d like to explain why I drew certain elements the way I did.
I’d like to reiterate that if BLF decides so, most of this stuff can be changed.

1. Driver + LEDs on a single board

  • smaller!
  • short thermal path from LEDs to MCU
    • though some drivers shorten the path with extra sensors on the MCPCB getting the same effect
  • some driver components need good cooling too, this solves the problems
  • but all components need to be rated for high-temperature work
  • requires costlier MCPCB
  • hard to swap LEDs
  • very hard to swap driver

2. LD-x4 / Texas Commander style driver

  • low height
  • little board space taken
  • fairly low cost
  • OK efficiency
  • PWM-free
  • unmatched regulated power for the price
  • unmatched regulated power for the size
    • this enables making good use of low-Vf LEDs that are hard to utilize otherwise
      • Luminus SST-40, Osram Q8WP, Lumileds Luxeon MZ, Nichia E21A just to name a few
  • unregulated power as high as with any other driver
  • with a single cell like the A family uses, it can support only 3V LEDs

3. Lights with TIR lenses don’t feature protective glass

  • more prone to scratches
    • but anti-reflective coating scratches too
    • anyway, it is replaceable
  • less prone to breaking
  • no tint shift
  • 1-3% higher output
  • 1.5 mm shorter and over 4g lighter
  • does any flashlight come with antistatic and/or hydrophobic coating? This possibility is lost.

4. DQG-style springless tail

  • light length changes with battery length - never longer than needed
  • large battery contact - minimal resistance
  • no spring and related resistance
  • ~2 mm shorter than PCB + spring, several grams lighter too
  • some members expressed worries about battery safety
    • I’ve heard about some problems with DQG lights, none was battery-related
    • TorchLAB ZeroRez is somewhat similar. No complaints that I’m aware of either.
  • battery rattles slightly when physically locked-out

5. 21350+21700 (maybe +21500 too) battery

Let’s start with why 21700.
It’s a new format and some say it’s the future of Li-ion. Personally, I don’t think so, but I’m sure it has a good future.
There are already very good batteries available in this size and some major players haven’t joined yet. Sony is probably the biggest missing.
One interesting 21700 battery is Samsung INR21700-30T. It is the most powerful cell on the market, beating any 18650, 20700, 26650 or 32650 cell out there.
The availability of this cell actually isn’t always great. Pair it with a FET driver in a low-resistance host (like any A-family light) and it will kill pretty much any low-voltage emitter. Often it will kill several low-voltage emitters.
In the future even more powerful cells may appear. May or may not, flashlights should be prepared regardless.
A-lights’ high-power regulated driver should be able to handle that case well.

  • alternative: 26700
    • thicker, heavier, worse for EDC
    • 15-20% higher capacity
    • for max power, can use 21700
    • could be made available with 26350 compatibility
    • actually I think it would be a good choice for the largest A-lights
  • alternative: 26650
    • as thick as 26700, marginally lighter
    • no 21700 support
    • with DQG tail it’s not any shorter than 26700
  • alternative: 18650
    • less comfortable to hold
    • a little less size, weight
      • very little because we can’t reduce head size - it is limited by driver board size
    • much smaller capacity
  • alternative: 20700
    • it’s uncertain whether it has any future
  • alternative: 32650
    • only slightly better capacity than 26650 with worse power handling? Sadly, I don’t consider it a good option

Why 21350? There are no 21350 batteries on the market now……

  • there are 18350 and 20350 batteries now
  • when 1100 mAh is enough, the full 21700 size just adds useless bulk
  • drawbacks?….I see nothing serious here.

So 21350 is just a why-not choice. It makes the lights better for some EDC uses without making them much worse for others.

It might be possible to support 21500 (and 18500) too.

6. USB Type C connector
Previously I used magnetic connector in the drawings. That drew criticism as a costly option. It is costly and I agreed with that, but thought it was worthwhile….despite that I didn’t have any light with magnetic charger at the time.
Now I do….and I love it. It really feels like the top option.
But at the same time this was the only posh option on the otherwise modestly planned A-lights. Does Type C work? It does. And it works well. Not as well as magnetic connector, but well nevertheless.

Magnetic connector:

  • adds a couple of dollars to the light’s price
  • requires proprietary charging cables
    • may either require the maker to add several cables with different connectors or force the buyer to pick one
    • if the user loses their cables, they have a problem
  • is the most comfortable connector option

Frankly, I still have mixed feelings about it. For me it’s worth it. But it’s BLF, so I drew it with the budget option.

7. Stainless steel bezel

  • bezel is the widest part of the light. Stainless steel enables reducing the width here for not-so-marginal difference in size.
  • maybe optional titanium would be possible?…