Physically it’s a good choice. But supporting USB 3.1 by protocol would make the project to expensive.
Also the 2.4A usable without USB3.1 are indeed quite a bunch of power (15W). More than enough to charge 1-4x 18650 cells with up to 1A and powering the lantern simultaneously.
Talk is being done
While there are very cheap chips to be found it is a tell tale sign Xiaomi is using a Ti chip in its powerbanks.
I asked the USB C question in the PM DBSAR, DEL and TK are having aboit the driver. But as always costs are an important factor and with all the mUSB hardware it is long from dead and loads if adapters can be found and surely will be able to be bought for many many years to come.
yes i understand cost is an issue not sure how much of an issue,
as for the usb-c connector it has one big advantage if done properly. 1 connector for charging and discharging.
also you wouldn’t need to support usb 3.1standard as this is a power back, im pretty sure there is a different standard for power delivery.
Either way, people are looking at the idea so it cant be all bad,
I have been playing with my Q8 with lantern attachment for a while and I noticed that the Q8 is pretty heavy for a lantern. And then I realised that this weight is not at all needed for a lantern: apart from the batteries the lamp may weigh next to nothing because the maximum power used will just be around 3W, so heat-path and -sinking is as good as irrelevant. A bit counter-intuitive for BLF, but I vote for a (sturdy enough for abuse but) lightweight design.
I definitely agree. If BLF is going to take on this project, I’d much rather see an original lantern design that strives to push the design of LED lanterns forward rather than a diffuser-like attachment or a design based off a flashlight that was never intended as a lantern. That said, I do like the size and form-factor of DBSAR’s prototype.
So it will feature 300lm?
Seems a bit low i believe.
I got the 3W from DBSAR’s discussion with sac02:
But even with 2A a really lightweight build is sufficient.
Three 7135’s provide more than enough light for this type of application. My similar in concept 4th annual contest entry, the mug-o-light, has three and I never run it on high. I understand why DBSAR reduced it to 2.
I think we talk 700-1000mA (3 * 7135 max)
The integrated shelf of the Q8 is not needed, a small flat area above the tripod mount for the USB connectors (well that is going with my idea of using the tripod mount to secure a rubber flap to ensure water proofing which seems logical to me)
Above that the diffuser and wires holding poles
So I expect the lantern to be lighter but some weight helps inbsturdy placement so is not bad.
Unfortunately, weight=good at BLF, while when I go out camping reducing weight is all-dominating!!! If I want a firm base I rather make the base wider instead of the light heavier.
Well true, but I don’t see a lot of fat on Q8 tube, tail and lower part head so removing the integrated shelf that is not needed and a good diffusing downwards facing led part seems the lightest 4 18650 config without going titanium
Seeing the HJK thermal images if powerbanks makes me think the few fins remaining on the head do have a function.
We are talking 172gr of cells
Plastic lanterns are plenty but come on, it only needs one time placing the backpack down wrong to render them useless.
I would be interested in this lantern. Thanks.
Djozz, just see how much metal is ditched looking at the Q8 an a rough sketch
The Prototype is based from a SRK body, but with the top of the flashlight sawed off, so its not as long as what a diffuser attachment would be on a Q8. (Also the lantern prototype is a “down-firing” LED set up, and is far more efficient, better light angle, and has far less eye glare than an up-firing lantern/flashlight-Diffuser has, ( especially when the lantern is on a table or carried by the top lanyard. USB-C port interface is not a good idea as its not the standard cord interface that comes with 98% of phones, tablets, portable 2-way radios, etc. The charge-out port would need to be the standard USB-A type plug. USB 3.1 format is irrelevant for a charge-only port, as there is no data transfer, only 5 volts DC power for charging. (its the came across USB 1. 1.1, 2.0 , 3.0, etc.)
As mentioned above XP-L & XM-L emitters seem to be in the most efficient amps-vs-lumens-output in the 700mA to 1000mA range. (1050mA (or three 7135 chips) produces around 460 ~ 500 lumens, plenty for lantern use. The prototype uses 2-7135s, ( 700mA ) ans produces average 300 ~ 350 lumens, and with the current down-firing XP-L 7A3 LED it seems close to a 40 watt incan bulb for output, and its still far brighter than any other factory bought LED lantern i have/tested.
Nice example drawing 
as you mentioned, the lantern would be shorter than a Q8/SRK with a diffuser head, as 25 % of it is removed for the lantern design. (seen below)
DBSAR, I hope this isn’t viewed as argumentative or a belabored point, but how are you estimating those output numbers? They seem high to me. I know it doesn’t matter in the grand scheme, but I like to have compulsively need as much accuracy as possible in all things I care about, lol.
I’m looking at Cree datasheet for XP-L V2 (based on availability of 7xx tints in V2 bin) at 1050mA and 25*C, is 446Lm. At Tj=85*C (this light won’t get that hot) it is 400Lm. I think it is safe to say somewhere between 400 and 446 emitter lumens at 1.05A So I think actual OTF output will be substantially less with not only a lens, but a diffuser included as well.
Looking at the Relative Luminous Flux vs Current chart, at 700ma my best estimate of the output would be 69.2% of rated lumens, so somewhere between 277 and 309lm (again, at the emitter).
djozz test graphs are similarly hard to read perfectly accurately (tabular data would be a nice bonus for future tests), and djozz is quick to point out his tests are not calibrated to any standard output. But his tests show about 310Lm at 700mA and 480Lm at 1A, for a higher binned V6 XP-L.
I think that diffuser eats more lumens than one might expect. I wouldn’t be surprised if OTF lumens were down by 30% from the emitter output?
I am so happy that this project got some traction. I have an off grid hut…and some solar panels. I know you all will like this flashlight when all electricy is off and the zombies are chasing you….
Thank me later when the zombies are here.
I used a Lux sphere to test various LEDs and driver set ups when i built it. From my tests then to your claims above my measurements are quite accurate. I posted above: ” 1000mA range. (1050mA (or three 7135 chips) produces around 460 ~ 500 lumens” were not talking single-lumen accuracy here, just averaged tests. I did my tests in the sphere with the bare LED, not a diffuser. This lantern prototype don’t really have a diffuser, just a clear main globe and a lightly frosted inner globe. Not a completely opaque diffuser as in many lanterns sense.
I used my solar 40-watt folding panel to power BT-C3100 charger to charge 18650s each day this past summer on my trip to the wilderness. It is possible with a built in charger for the lanterns cells, & using a 20-watt or higher panel?USB charger, it is possible to sustain this lantern indefinitely with charges to power it for several hours every night.
Update: currently testing to shoe-horn in a TP4056 based charger module in the lantern prototype, to see if indefinite sustainability is possible with running the lantern on high every night for 4 hours, then charging the next day using a Poweradd 40-watt folding solar panel multi-charger with a 2 amp USB charge output)