I’ve actually tried it on a Q8, both with the light on, and the light off. I put 3 fully charged 20A Samsung 25r’s in with a fully discharged 4.7A LG-F1 and nothing happened either. After about 10 minutes, the LG cell peaked up to about 87ºF, after 15 minutes, the temp was lowering, and after about 35 minutes it was roughly the same temp and voltage as the others. At no time did anything get hot.
I'm also playing with LiPo batteries for a small RC hobby, and balancing packs IS a real thing there (if not, you always finish to get some cells overcharing: the shortest path for heated and smokey disasters).
For our product I think the simple question here is "Do the LT1 charging circuits monitor each cells individually?"
If yes, I see mostly no reason that mixing various charged state batteries for charging will produce an hazard. Though the answer to that one is not universal, like, for general use, that's another question to know how the LT1 is designed to handle various charged state batteries.
Praising the user to be cautious, thanks to all the warning in the manual, still seems the cleverest way to handle batteries.
it would be interesting with cells that can’t handle more than 5A
A balancing circuit is only required when the cells are in series. When cells are connected in parallel they will naturally balance on their own. No special considerations are required when charging batteries in parallel.
You could even use multiple different capacity cells in the LT1 and it would be just fine.
Wouldn’t the high internal resistance of the cell naturally limit the amount of current flowing in from the other cells?
I think that's the most accurate question reformulation: are the batteries handled in serie or in parallel in the LT1?
They are in parallel. If you look at some of the photos posted in this thread you can see that the positive contact on the driver board is just a ring that connects all four positive ends together.
So, you’re saying that nothing would have gone wrong even with a turbo mode lantern that might have a 10-15A draw?
Exactly, it is of absolutely no importance because all batteries are connected among each other, totally independent of whats happening on the driver side.
Basically, there is a “short circuit” connecting all 4 batteries on the positive contact and the same is happening on the negative contact as well. That is why the batteries will always have the same voltage.
In fact some of the batteries are acting like the charger for others, not a perfectly nice charging regime but the voltages are not that different so extreme currents are not happening, and with voltages closing in to each other at the end the current even slows down nicely.
While there may be empirical evidence that shows mismatched charge levels will not automatically burn a lantern to the ground, there’s also an old saying about how making something foolproof tends to result in the world presenting you with a New & Improved Fool.
Liability laws force manufacturers to do what they can to protect the lowest common denominator demographic from themselves, despite their best efforts to win themselves a Darwin award. For this reason, nobody should expect any official instructions or communications from the manufacturer or developers to condone anything but the absolutely safest options.
That said, Carry On. Matches to the Left, Gasoline to the Right, Anvils dead ahead.
I think there would be a difference if the lantern in question was on. While off, they’d be the same because the LT1 and this hypothetical lantern (LT1 SS hyperturbo deluxe?) both have the cells in a parallel configuration where the all the +’s and all the -’s of each cell are physically connected when the tube is screwed on.
Whether having the light on just after inserting the discharged cell would do something bad is beyond me, but if this is bad/dangerous, then doing so with a higher powered light would presumably be “more bad”.
I would assume the opposite. A second load (a turned on light) would suck up amps that would have otherwise been available to abuse the low cell.
But, I’m not an electrical engineer and can’t recall which part of Ohm’s Law gets handcuffed to the bed, so I’m a bad one to take advice from.
I agreed with everything you said prior to reading the above quoted ending and then I almost spit out my coffee cuz I was laughing so hard!
I received my LT1 yesterday (Ordered on Amazon Oct 24th received Nov 5th) 12 days is pretty good from China to my rural Utah town. I put my cells in and it just worked. I did notice when I unscrewed the battery compartment that the wrap on one of my cells was worn, so I looked inside the lantern more closely and noticed one of the screws that holds the board in place was not flush with the board. It stuck out about 1/8” and had obviously rubbed against the top of one of my cells as I could see plastic dust from my cell on the screw. I tightened it up and checked if it was still rubbing - it was not. So I recommend you check the screws holding the board in prior to loading it with cells. The wrap is not seriously damaged so I don’t have to re-wrap my cell.
The lantern was very well packaged. I was concerned when I got notification it was delivered and watched the video of the mailman throwing it at my front door step, but zero damage thanks to the good packaging. I have not tried charging the cells in the lantern yet, but everything else works well. I am very pleased with another amazing BLF project! Thanks to all those who have helped make this a reality!
TK posted some accounts of melted springs.
I think this is logical, and speaks more to the issue of whether it is bad to run a light at all with a multiple cells in parallel having one cell discharged. My thinking was that if it was bad to run the light this way (if having it on was worse than not) that it would likely be more bad to do this in a hotter light.
From your logic (which sounds good to me), it would be less dangerous to run the light after inserting the discharged cell than to wait for the cells to balance before turning it on. All else equal, a more demanding load would be less dangerous in this scenario.
Cells will never be fully balanced anyway, but they can be “close enough”. Many will probably just get 4 cells, use the on-board charging, and leave them in there . This would be about as balanced as we can hope for.
For anyone pondering this, why not maximize the performance to weight ratio and get 4 good cells to begin with? If you can afford a $50 lantern, you can probably afford the extra $13 for 4 decent cells to be included.
The cells will be “balanced” nearly instantly once the connection between they is made. They’re in parallel. They act as one big cell and will all be at the same voltage.
That was with one of the batteries reversed (which is bad news and luckily there are some safety features for that, like a collapsable spring and ultimately the internal battery fuse), it was not a case of correctly inserted batteries at different charge states.
The balancing will not be nearly instantly, it takes time to charge the lower voltage cell.
I meant when tested individually.
Even brand new, two cells of the same model will not be exactly the same. My point is that there is a “fudge factor” and we can calm down a bit about less than perfectly matched cells IN THIS LIGHT (emphasis added for future clarity). Anyone concerned enough about this can either:
A) buy the lantern with Sofirn’s cells and keep them together in the light (good value)
B) buy new matching cells of another variety and keep them in “married” sets (possibly best performance by utilizing 3500mah cells)
If you aren’t concerned about slight differences, carry on with your laptop pulls or whatever…
I purchased some sets of these a while back, and haven’t used them elsewhere so they are what I’ll be using:
These are probably a better value today: