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

I’d suggest using thermal regulation, but that’s physically not doable on this light.

However, if it’s an issue, one thing we can do is set the default ceiling values to a sane level… and then only turbo will be hotter. In practice, what that looks like is having a regular set of modes, plus one. So if it has modes 1, 2, 3, 4, and 5 in the normal range, turbo would only be 6 on a visual scale. It doesn’t look much brighter, even if there’s a significant temperature difference.

I thought that firmware have thermal control, isn’t it?
Thermal sensor should be it top part.
On the other hand it is not good for lamp if it change output from every gust of wind.

I think the best decision is one direction temperature control

The firmware has thermal regulation, but it won’t work in the lantern. The sensor is built into the MCU, which is in the middle section of the light. So it cannot sense LED temperature. They are too far apart.

An external sensor doesn’t work either, because the MCU has no pins left.

Maybe we could still use this internal sensor to automatically adjust the ceiling based on the ambiant temperature, but I think that a lamp this size shouldn’t have problems cooling a thousand lumens with a few cooling fins added. If that isn’t sufficient we could maybe try to use the center bolt as a heatpipe to the lower section and use it for cooling as well.

I also thought about this.
Central bolt made of steel it is bad heatpipe. But we can add copper pipe around the bolt. This also increase crushing strength of construction.

For example pipe d=10mm h=50mm thicknesses 2mm take 10W(definitely more than thermal power of lamp) with dt=20C.

Non-aholics run stuff wide open all the time .They have no concept of runtime and have the brighter is better mentality .Pretty sure this light was never intended on becoming a lumen monster .

Runtime/UI /tint and cri are my top concerns .

If you need more light ...buy two

:+1:

you mean you don’t want a lantern that so bright it gives you a tan at 0000hrs? why the heck not???

:wink: :wink: :wink: :wink: :wink: :wink: :wink: :wink: :wink: :wink: :wink:

I think the goal is to build the lantern so it has enough thermal mass and surface area for its power level, so it physically cannot overheat during normal use. A heat pipe from the top to the middle might help increase the thermal capacity, if necessary. But we don’t know yet if it is necessary. Maybe if it has a maximum power level around 1.5A, it might not need any more changes.

I don’t really have a good solution for heat on this light, aside from just trying it to see what works. Perhaps some vertical fins on the top section could help increase surface area in a manner which encourages air to move even without a breeze. For example, when hanging inside a closed tent.

When used outside, it should be safer since the air is always moving at least a little.

So far in my tests at 1.4 amps at the cells on maximum mode with the four LH351D LEDs the top of the lantern has not got to hot even after a hour running on max. ( no higher than 45 ~ 50 degrees) i doubt it still wouldn’t be a concern even with 1.6 amps considering the top is a large solid mass of aluminum.

This is something I do not need but really want… I’m not sure how I’m going to explain this one to the misses but please put me down for one!

It’s an emergency light for power outages - (for her safety and convenience) :wink:

I am increasingly mystified at what people are expecting from a useful practical efficient lantern.

The very concept of having a FET, and a “turbo” mode is utterly ridiculous. I hope I have mis-understood and that was just a naive poster spouting nonsense.

Higher power and better heatsinking could perhaps have been achieved by upward-firing LEDs from the body, the same as most other LED lanterns do it, but this is different. It fires down from the top. And it is a good decision I think. It ought to be capable of easily supporting four LEDs, if driven sensibly at their most efficient points. Not over-driven to ludicrous levels.

Which has been a key design decision, based on practical experimentation. And the correct way to go IMO for a practical lantern.

Don’t listen to the “max power, push the LEDs to the max. 30 seconds on turbo is great, let it burn” idiots. Balance in everything. This is not a torch, it’s a lantern, designed for the long-run. Don’t over-stress anything, keep it to manufacturers’ data sheet parameters, then it might be supremely reliable and out-last most of us.

PS: that does mean that a FET has no place in this driver, in case you missed that.

I think I used that excuse already, not sure if she’s going to fall for it a second (or is it third) time… :stuck_out_tongue:

@Tom Tom, we are using the FET as a linear regulator, not in a direct drive setup.

Do you have schematics for that circuit?

Yes.

Lexel posted the driver schematics for both a few pages back.)

The Emisar D4 is a hot rod. It can run at like 80 Watts with the right combination of battery and emitters. Its “turbo” is way beyond what it could actually sustain with such small mass. It could easily damage itself or start fires.

The BLF lantern is not a hot rod. It maxes out at around 6 to 10 Watts (TBD), and it has significantly more thermal mass. It may not have a “turbo” level, but if it does, it will probably mean that the temperature goes up to 25 C below the emitter’s rated operating temperature instead of 35 C below. It could potentially get hot enough to be uncomfortable to touch, but it’s very unlikely to cause any damage.

The FET-based driver uses a linear FET design to achieve constant regulated current. It is not direct-drive. Instead, it’s like two of led4power’s constant current drivers. They’re also based on a FET.

I personally prefer the 7135 version of the driver, but it’s not because of anything related to heat or brightness. It’s mostly because the 7135 version uses fewer pins, while the FET version sacrifices or complicates some features. For example, the FET version has no pin to control the button LED, because there was no room for it.

I wish I was earlier on this list… but me on please!