*BLF LT1 Lantern Project) (updated Nov,17,2020)

So possibly a large 8 x 18650 base that would screw onto the existing 4 x 18650 LT1 (for a total of 12 x 18650). That is ingenious and I like the way you think. And of course, Id buy several! That would also make for a great high capacity power bank.

Admittedly, my vintage Coleman lantern collecting obsession has reached new heights. All attributable to my inability to restrain myself from acquiring these finger burning photon emitters.

Just stumbled on this thread - fantastic project and glad to read that OP’s personal life has gotten better :+1:

An all-aluminium body and High CRI neutral white emitter, these are just the sorts of things I’m looking for in a lamp :heart_eyes:

As an Eneloop user, I’ll be on the lookout for the LT1-AA version.

Keep up the good work :beer:

Ok I received the my lantern I used https://www.amazon.com/dp/B097MN6P1B?psc=1&ref=ppx_yo2_dt_b_product_details and purchased the “New LT1 Kit”

It has a green light and has the following:
Imgur

Presumably this is the latest rev?

Could anyone please help me out, my lantern’s light output gradually decreases in time? I factory reset by unscrewing and holding the button for 4 seconds while rescrewing the body back. Then I double checked by doing 13H for the factory reset in Andruil 2.0. I then changed the tint to bright white by 3H, but the issue that when the light is on the lamp decreases the brightness until the lamp is off after 2 second increments!

The batteries are charged and protective covers removed? Did you try other batteries or measured the ones that came with it with a DMM?

That is odd… never seen that happen before. Maybe Toykeeper or Barry can chime in on that… if the driver is defective, contact Sofirn i’m sure they will help! - DB

This sounds like a weak battery (getting “low-batt” or “empty”), but if the batteries are not “low-batt” (can check using the triple-click from Off for “Battery Voltage Check” function).

If batteries are not “low-batt” (not nearing 3.0v), then it could be some poor contact issue (fully-charged batteries might be detected as “weak” due to poor contact somewhere — sometimes it could be due to an o-ring that’s entangled and interfering with the contacts).

So … What model to order ??

Finally managed to figure out how to reset the lamp. I fully charged it, then had to unscrew it and hold the button down for 4 seconds. The manual had this kinda hidden and not well marked out on how to reset the lamp.

I hear a lot of people like to set the light to 4000k. How do you all set it to a specific color temp? Do you just ramp up to 5000k, release then hold it back down for 1 second and approximate that as 4000k? It would be nice if it ‘clicked’ at 500k increments.

Approximate it. See how long it takes to go from one end of the ramp to the other, and do half that.

Or better yet, don’t worry about the exact temperature. Just set it for what looks right in the current context. During the early evening when the sun has set but there is still a fair amount of glow from scattered light in the sky, I might set it all the way at the 5000K end of the ramp. As the ambient fade, especially if I have a campfire going, I adjust it progressively warmer.

I have the one with the version 5.0 driver. The firmware was updated from Andril to Anduril 2.0.

The flashing key/pogo pins did not work. I had to remove the driver and use the SOIC clip. It was successful. It is all good. The flashing kit with this flashing key/pogo pins works on other lights, so the problem seems to be in the light itself. Other than that, there is no problem. Everything works.

I am curious what I did wrong. The error showed the connections were not good. Has anybody had the similar experience?

I just received a version 5.0 from Amazon. Am I missing any functionality / feature by not having the latest driver? Perhaps I should order from Sofirn instead? Thanks!

Take my money!

I really hope that project comes together. Having a 3rd red channel is the one thing I’d really love to see. It makes it useful for so many additional applications where red is required: stargazing, sailing, avoiding bugs, etc. (Yes, I know that requiring red is a hotly debated topic, but lots of groups still require it, and it’s easier just to go with the flow and have a red light.)

The power bank feature would also be nice with 21700s, you could get a nice 20 Ah (~72 Wh) capacity with that. I don’t find I’m ever lacking for run time on the LT1, but including a power bank would make that extra capacity really nice.

Quick update. My “Sofirn 1.0” Powerbank LT1 does not charge my iPhone with a USB C-A adapter. But it will charge my Wurkkos FC11 with that adapter.

Did you try using a USB-C to Apple Lightning cable when charging your iPhone? I suppose the iPhone‘s chipset expects a special code in order to start charging. When you use a type A to type C adapter in between, the chipset communication between LT1 and iPhone might become corrupted.

I don’t have one, but will see if I can borrow one to test. I did wonder about that, but also felt like if it normally charges from USB-A it isn’t expecting a whole lot. This is a topic I’m totally clueless on though.

Well, sh*t… As it turns out, a DIY modification of the indicator LED color scheme might be a bit more difficult than I anticipated:

I was hoping the reassignment of LEDs would be possible by simply swapping some of the wires connecting the driver (BLF-LT1-A2) and switch PCBs. Or at worst case, swapping the SMD LEDs themselves on the switch PCB assembly. Plus if necessary, replacing the current limiting resistors. The datasheet of the powerbank IC also supported this theory.
Boy, was I wrong, though…
Here is the reverse-engineered schematic of the switch assy and its connections to the driver PCB:

The circled numbers denote the identically numbered wires between the driver and switch PCB

As you can see, the LEDs controlled by the PB controller are connected antiparallel to each other and driven sort of “differentially”. Which makes wire swapping not feasible.
What’s even worse, the blue and amber LEDs Sofirn chose are in fact not separate components. They are part of the same 0606-size duo-LED. (The green one on the other hand, is a plain 0603 single-color led.)

The different package sizes and the fact that the blue and amber LEDs are integrated means swapping the existing LEDs around is also out of the question.

At this point, the “easiest” option left is to buy new LEDs, 2 duo and 2 single with the colors you want, and replace the current ones with them. If you’re determined enough to do that, and you intend to use a hot air soldering iron for the removal part, be careful not to melt the tact switch (wall it off with Kapton tape or aluminium foil), as the clearances are awfully tiny here… If I were to go ahead with this mod, I think I’d just use 2 normal irons (or an SMD tweezer iron) instead, just to be safe.
Here are some examples of applicable replacements for the duo led:
https://uk.farnell.com/kingbright/kptb-1615surkcgkc/led-red-green-80-50mcd-smd/dp/2426238
https://uk.farnell.com/kingbright/kptb-1615esgc/led-red-green-7-12mcd-smd/dp/2426236
https://uk.farnell.com/lumex/sml-lx0606igc-tr/led-1-5mm-x-1-2mm-red-green-smd/dp/1789153
https://uk.farnell.com/dialight/598-8410-207cf/led-red-green-65-59mcd-633-570nm/dp/3548426
https://uk.farnell.com/w/search?led-colour=red-green&packaging=cuttape&st=150066
If you live in luckier parts of the world where the really big distributors (Digikey, Mouser, etc.) do not have absolutely ridiculous shipping fees, you might find more options.
Unfortunately, I am pretty much stuck with Farnell, and in the applicable package size, I found only the handful of LEDs above in their catalog.

Fun fact: the indicator LED driver configuration utilized in the LT1 is not documented at all in the IP5310 datasheet. Its 2-LED mode is supposed to drive the LEDs in a basic single ended configuration, with no series (current limiting) resistors, since the IP5310 itself has integrated current regulators:

So either Sofirn decided to use the driver “in a creative way”, or it is an intended, but undocumented feature of the IP5310, borrowed from its bigger brothers which support differential LED drive natively.
What I still cannot wrap my head around though is why the engineer at Sofirn chose to implement the LED drive this way in the first place. The usual argument for the differential approach is to save an extra wire (no dedicated GND needed).
Bun the LT1’s switch PCB needs a GND wire anyway for the switch and the green LED, so in our case the number of wires connecting the 2 PCBs were not reduced… It is also strange they went for the blue-and-amber duo LEDs, which are rather exotic, and I imagine more difficult and expensive to source, instead of the more ubiquitous red-and-green ones combined with standalone amber LEDs. I guess we’ll never know…

Anyway, happy modding! :wink:

Some extra details about the driver (BLF-LT1-A2) :

  • Some photos
  • 7 x AMC7135s per channel, all hardwired
  • The programming/debug pads are directly wired to the Tiny’s pins 1: pin1, 2: pin2, etc.
  • The power supply of the Tiny looks like this:

    Glancing at the previous driver PCB’s, I’d say it is probably unchanged.
  • A simple, but effective pFET-based reverse battery polatiry protection is implemented. Nice!
  • The circuit built around the IP5310 pretty much coincides with its official reference schematic (except for the differential indicator LED drive), so it should be fine.
  • As already determined, the IP5310’s dsplay engine is used in 2-LED mode. Which is a clever choice, since, as opposed to the higher LED number display modes, it does not utilize the embedded Coulomb counter / fuel-gauge algorithm for triggering the low-battery warning. It uses a simple voltage comparison with a predefined threshold (2.95V, typ.) instead. This is good news, because, the fuel-gauge is guaranteed to “get lost” when other consumers keep sipping power directly from the battery terminals (in our case the white power LEDs), since it has no way to measure that and incorporate it into its calculation.
  • The IP5310 is used in the following configuration:
    (Overall completely reasonable, IMO)
Pin Connected resistor Corresponding config setting
1 1k to Vcc 2-LED display mode
3 N.C. 4.20V Nominal charging voltage
4 N.C. fuel gauge config - irrelevant for the LT1
5 10k to GND Battery internal resistance 45mR
6 50k8 to GND Dummy NTC

Production quality of the driver PCB assembly (BLF-LT1-A2) in my LT1:

Overall, not bad at all:

  • the visible solder joints look nice,
  • the inductor (the only heavy component) is glued down,
  • the wires they used are of good quality: thick but still flexible,
  • the wires are not glued down => if you accidentally break them, they can be easily desoldered,
  • the hand-soldered joints (of the wires) are robust.
  • There is noticeable “solder balling” on the board, though. I.e. free-standing little balls of solder stuck in the flux residue on the PCB. At least two of them should be noticeable in the photos linked in my prev. post. I counted at least 5 of them, total. Fortunately they were not large enough to be a real risk of short circuit if they break loose by heat / vibration etc. Your mileage may vary though… This is a well known and studied production defect with reflow soldering, usually caused by expired or low quality solder paste or a suboptimal reflow temperature profile.

Funny, I usually rate wires good as high strand count - flexible, while cheaper wires are low strand count - stiffer. Dunno if the cost reflects that though...

Lot of suspect lower quality wires in the lights are low strand count, but the Turnigy brand and what Hank uses/sells is high strand count, also 200C rated. Cheaper wires seem to be 150C rated.

I know the insulation layer can vary in thickness as well, which can get confusing. For our use we want usually moderate thickness - not too thick to fit the holes and for clearance, but not too thin to cut or tear easily.

I would think the LT1 driver circuit and I/O pins assignments/etc. is open source? See post #736 here. Ohh - don't see the LT1 driver though on DEL's OSHPark list.

Maybe DBSAR knows if the LT1 circuit design is available publicly? Sometimes these relationships we have with the manufacturers has some limits, other times it's just lack of asking, or communications, etc.