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

It has been done before. Cut the power level in half, and it doubles the runtime. For example, a Convoy light with 4x7135 driver runs twice as long as one with a 8x7135 driver. But it puts out half as much light.

On the lantern, there isn’t much need to remove chips to increase the runtime… just turn it down a level or two and it’ll run longer. Go down all the way, and it can run nonstop for about three months. You don’t have to run it at full power at all times.

Agreed

updated

added one for two total. Price estimate $40 or so (less?) has been discussed, but is not firm.

Here is another :slight_smile:
1079 T18
1080 agent80
1081 efi5phd
1082 Coyotehawk
1083 Terrys8
1084 Rdubya18
1085 wheremydonky
1086 wheremydonky
1087 lohtse
1088 zeroflow
1089 gottawearshades

I am also interested. Add me to the list.

New here, can you clarify? Does this mean the first run for people here that said they were interested won’t have power bank function, but it will be added for later production runs? Or does this mean something else? Thanks.

We decided to drop the power bank option to reduce cost per unit, and get it into production sooner. (it will still have the charging function however. Originally the lantern was to be designed to be a simple, low-cost better quality lantern as a better option to all the low-quality plastic lanterns commercially available in stores & on the market, and adding to many bells & whistles will defeat that purpose of the low-cost part.

added!

Got it, was just making sure.

Good point.
But what about the possibility of an advanced version after the BLF Lantern is finished ?

There is plans for a deluxe version at a later date.

I am in for one. please add me to the list.

Definitely works for me. I like having the charging function, although I probably won’t ever use it. But, the power bank function is completely useless to me. I’d rather have light than to power anything else. So whatever power is in the lantern needs to stay there in my case. I know others are more hard core in their camping, hiking, caving, etc. and would find having a power bank built-in to be quite useful as it’s one less thing to carry.

For a future model we will look at the power bank function. for now the built in charging will be a great feature to have on long camping trips or off grid use.

Agreed, the charging function is much more useful to me.

“Via in pads” is generally a no-no. Google it. Unless you really know what you are doing, how to tent the solder mask etc.

They potentially suck out the screen-printed solder resulting in a weak joint.

Then there is ROHS lead-free solder which doesn’t like this either.

Then the idea is that the underside provides good gold plated vias for the pogo pins to contact. Which they may not if the via is plugged with solder.

Lots of things to go wrong here, for no good reason. Separate the vias from the pads is my suggestion, I see plenty of area to do so.

Edit: agree on powerbank delete decision. I certainly don’t need or want it.

PS: I don’t know what charging chip you have chosen, but please be sure that it can cope with a small solar panel and dump every bit of available energy into the cells, no matter how weak the light, and how variable, night, day, clouds, shadows etc. Not all can, some only work in certain conditions and trip out otherwise.

This is nothing like charging up e.g a mobile phone from a mains adapter. Totally different situation.

Edit: I mean accepting current from any solar panel, from a standard nominal 12V panel (actually a lot higher), to one of the the popular portable USB output (5V ? delivered wastefully) devices.

TBH I think that making it only a USB input is a waste. I’d rather see a full-featured input via a rugged co-ax socket, that can accept almost any supply, from a 12V solar panel, to a re-purposed laptop 19V adapter, to a 12V or 24V automotive connection, to a USB passive or active adapter of any type.

That was my original plan & the reason why i want to limit the charge rate to no more than 1 amp-draw from the USB line.
I know some have argued & cried to want it to have a 2+ amp “fast charge” but that’s not needed or practical for this lantern to be a true off-grid capable light. I am still wanting it to have the maximum 1-amp charge rate for many reasons. One is that a 10-watt small solar panel can be able to charge the lantern without suffering to much voltage “sag” with the heaver amp draw of a 2+ amp charger. on the V1 Prototype i used a single TP4056 charger module, set at 1-amp. On the 10 watt small panel it still charges the lantern with four 18650, 2500mah cells from 3.4 volts to full charge in 1 sunny day of light. (My test it took 7 hours to fully charge) then using the lantern for 5 ~ 6 hours average per night for 3 nights on medium & high intermittently with no problem or worry of it going dead. My tests also showed that just 4 hours average per day of sunlight on the same charger charged it back up to full after 4 to 5 hours of use per night, meaning the lantern can run every night for years as an off grid light source using small solar panels.
I did a test with two TP4056 chargers charging four cells ( in a 2-bank box) and the 10-watt charger with the 2-amp load, would loose so much voltage from load-sag the charger would continuously turn on & off, and the batteries did not charge up at all after a full day of sun. ( same goes with charging from some of the smaller 12-volt adapter USB power plugs, they can’t sustain much past 1.2 amps before they overheat, cause voltage sag, or burn out. ( i burned out a couple of them during load testing.
To try to design it to be a “multi-voltage” charging is just adding unnecessary costs again, (another reason why were dropping the power-bank option for this first lantern model.) The team has set the design now to get this rolling, as its been to long already discussing different options and delayed this project way to long.

@DBSAR, I have a TP5100.

It’s quite a bit more efficient than the TP4056 since it’s a buck converter, and doesn’t heat up much, if at all, at a 1A charge rate.

Since it’s also more efficient, that means you don’t need as much current from the charger to achieve the same charging rate, meaning you can slightly lower current, which will lower the voltage drop of the solar panel and the cable, making it easier on the panel and more efficient :slight_smile:

TLDR: Let’s go with the TP5100 if we can.

interesting, i have not tested that module before.
(though it will be Lexel who is designing the driver to determine what he can incorporate on his driver prototype for that built-in charging circuit.

Outside of this project, I’m working on adding support for attiny1634 and/or attiny841, which both have more pins than the attiny85. This should allow Lexel’s dual-linear-FET driver to work, and also increases the ability to control a powerbank circuit.

But there’s no point holding back the lantern project until that’s done. It makes more sense to do the lantern now, and then maybe make a lantern V2 later with more features.

About tiny1634 vs tiny841, the latter is generally a better chip… newer, at least, and more flexible in how it’s used. The main drawback is it has only 8 KiB of ROM, while the tiny1634 has 16 KiB. And this matters because, um, Anduril already uses almost 8 KiB. I filled up the ROM with things like candle mode. This isn’t an issue for the lantern because it doesn’t need thermal regulation, so that’s a big chunk of code I can leave out. But on other lights, the extra ROM should be pretty helpful.

That would definitely be a good set up for a future deluxe-version of the lantern later on after we get the lower-cost standard one into production for now.