So, when we receive our LT1 we will be able to tell if we have first batch, second batch…. by the date on the last page of the printed manual that will come with it?
Looking at the official YouTube video, I’d like to understand a bit more about the charging. It sounds like a charger which isn’t capable of delivering 1.5A may get a bit hot unless you desolder a couple of the points inside, as shown.
I don’t mind so much about the excess heat per se, but if I plan on mainly recharging this using a 8w solar panel, which will deliver 1W at best, am I going to get more recharging efficiency by desoldering?
My experience with solar charging suggests that you are unlikely to have an issue with overheating of the charging circuit in the panel - it simply won’t produce enough power to do that. (Although, sitting in hot sun on a summer’s day doesn’t help.)
In theory, there is a chance that too much “load” may cause the panel voltage to collapse but I’ve never noted that happening with my panels. The built-in USB regulator perhaps prevents that? Even my little 7W Goal Zero still manages its full output into power banks that draw much more than that from a mains adaptor.
Den noted a small charge going in (140mA?) when charging the lantern from solar on an overcast day, so the circuit seems designed to just take what it can get.
I guess the only way to know for sure would be to do some tests with a USB power meter, solar panel and soldering iron.
Let’s hope someone with a better understanding of the electronics behind these things can chime in.
I agree with gadabout, I doubt you’ll see overheating of your solar panel unit’s voltage regulator. I’m not sure the adjustability between 0.75A and 1.5A is all that useful with the present design, but it is something DBSAR wanted as a capability for lower power solar panels. Hopefully he will chime in with the details as to why, as I’m curious also.
If you draw too much current from a bare panel with no regulator, the voltage will plummet and you’ll lose power.
Panels with regulators vary a lot, depending on the regulator design. A panel with a basic regulator will still see plummeting voltage and lose power if you try to draw too much current. A better regulator may be able to mitigate that effect, but it will still have to throttle down the output power to do it.
This then raises the question of how the device you’ve plugged in will react to having its power supply throttled down. If it gracefully draws on whatever power is available - as many powerbanks do - you’ll be fine. If it’s picky about its power - iPhones are infamous for that - then it may just give up and stop charging at all.
That’s why the standard recommendation for charging personal electronics from portable solar power is “solar charge a powerbank, then use the powerbank to charge your other devices”. It’s less efficient - having the extra charging step costs you energy - but it’s more likely to work reliably.
You don’t need to do that for the LT1, though, it’s designed to pick up where it left off and charge whenever there’s enough power.
On a related note, some solar panels have a regulator which will turn the power off and on again from time to time. This sometimes helps in variable solar conditions, because cycling the power like that may reset a picky device and convince it to start taking a charge again. It doesn’t always work, though.
Unfortunately, manufacturers don’t seem to specify what their built-in solar panel regulators can do - they just say “5V USB output”, maybe adding a current rating and that’s it.
Ultimately, you just have to try it and see what happens (having first checked that the panel can never produce too much voltage, of course).
The ability to change the stock 1.5A charging current to 0.75A adds versatility, because a panel producing 5W - 5V at 1A, for example - will struggle (at best) with the stock 1.5A configuration. Letting people modify the LT1 to charge at 0.75A means they can adjust it to better match the lower-powered solar panels they might already have.
In addition, lower charging current also means that a larger solar panel can continue to operate even in less favourable conditions (thin, hazy cloud, for example). Some people might prefer to give their LT1 a better chance of charging in less favourable conditions, even if that means sacrificing full-speed charging in better conditions.
Ok, I dug through the group chat and found some testing DBSAR did with a few different solar panels. This may be in the first post as well, didn’t check there.