Thank you. At present, many people have proposed that this storage function will appear on many chargers
If higher current discharge is required, the cooling fan is very necessary ，maybe two fans, or larger aluminum fins
Need 4*2a or 4*1.5a, 4*1a discharge?
4x 26800 is awesome I would love to be able to adjust charging amps from .5 to 2 amps.
An option charge to 4.1V or 4.0 would be really nice but less important.
The market for 26800 cells is relatively small in the enthusiast flashlight world. It is becoming more popular though.
Here are a few flashlights that take a 26800 cell:
Astrolux FT03
Convoy L6 with 26800 tube
Convoy L7 with 26800 tube
Convoy L8
Convoy M3C
Emisar DM1.12 with 26800 tube
Emisar D4SV2 with 26800 tube
Lumintop D3
Mateminco MT04 with 26800 tube
Nightwatch NI03
Nightwatch NSX4
Access to 26800 cells is another issue. Enthusiasts may need to bulk import 26800 cells and resell locally to obtain them at an affordable price.
I don't think it's a big market right now, but it could be in the future.
There is no great multi-cell 26800 charger right now, so I think a good number of people on BLF would buy one.
Vapcell would own the market, and maybe more 26800 batteries and flashlights would be introduced because there will be a great charger available from Vapcell.
Max 4*1.5A discharge is probably good for cells that we use for flashlights.
If the charger supported protected 26800 cells, that would make it easier to try to verify the capacity.
If there are 26800 batteries with protective plates on the market, the length is expected to be 86mm，even more
If this charger is compatible with 16340, the spring is a great challenge and needs to be adjusted
If only 18650-26900 is charged, the design is very simple
Do you think it should be compatible with small batteries?
You didn't ask me, but I have an opinion. 
It would be nice if it were a universal charger that could also charge AA and AAA batteries.
If it could charge 16340 cells as well, that's even better.
Yes, support for small cells like 10440 with a 250mA charging current or less is nice.
Protected 26800 probably isn’t necessary. I mentioned it to try to cover all unprotected 26800 lengths.
Dimples on the negative terminal and a protruding positive terminal (e.g. S4+) make it possible to charge cells with a recessed positive terminal. Film around a 10440 cell may not allow the negative end to touch a flat negative terminal.
Perhaps a 4-slot charger could be designed for up to 18650, and a larger 4-slot charger could be designed for 18650 to 26900.
Have a 4V/80% charge option for those who want to charge batteries to 80% so their batteries will live longer before wearing out from age.
My personal opinion is that supporting 18650-26800 is perfectly fine. There are plenty of other chargers suitable for smaller sizes but very few for larger sizes.
I think one mistake manufacturers make is that if the charger doesn’t support smaller sizes that it is suddenly going to have no market? Personally I like longer chargers as it makes getting 18650/21700 in and out of the charger easier.
I would like to see the following;
*I am not overly familiar with the limitations of USB-PD in terms of power delivery but I don’t see why it wouldn’t deliver enough power. Personally I would take a slight charging hit (Maybe a max of 3A x 2 slots or 2A x 4) in order to have USB-PD input.
**I would say if you could include 14500 size batteries that would also help your market. They’re a lot longer than 16340 and I don’t think would require too much additional modification. I would have a lower minimum charging current if supporting 14500 batteries.
By eliminating shorter batteries you can cut costs of manufacturing/R&D as you have said.
Only other feature I can think of that would be nice is if it also had USB output (Either through the same port or another port), but this isn’t a deal breaker.
As TimMC said above the form factor is slowly becoming more common but availability is definitely not the best. I purchased a bulk quantity to sell into my small local market which has worked well and one of the most common question is “Which charger” to which I reply XTAR SC1 Plus as it’s essentially the only good one on the market.
I currently own and use the S4+ daily it’s a great charger all round.
Some folks dont like the full charge bell sound, personally i dont mind it but it isn’t loud enough.
I have some AB cells with USB C on them and i hate them, dont quite fit the S4+, 26800 capability would allow charging any 21700 battery.
I’ll second TimMc request for a storage mode.
Slightly stronger springs as well even though the current ones are ok a bit more tension will help secure smaller cells a bit better eg. 10440/14500.
The charger that I would use a lot is one that analyses all li-ion cells that are inserted correctly, and charges them correctly. So also smaller cells and old cells are analysed and charged correctly. At the same time it must have a good display with as much information as possible simultaneously displayed for all slots (so no toggle-button clicks needed).
It happens too often that I have to insert a cell several times before a charger picks it up correctly. Or the charger declares a half-full cell as full all of a sudden. And then I take it out and insert again and the charger starts charging correctly again. This happened with Soshine chargers, Liitokala chargers and Xtar chargers.
It is nice if the charger is compact and can be USB-C powered. A two-slot charger is what I use most. For me if it charges just li-ion cells that is fine.
Several charge currents are nice, and the option to stop at 80% charged is nice, but these are secondary wishes, the first is that it charges well.
I know exactly what you mean here, i can’t figure out why this happens :rage:
Yes its nice but it would also be a competitive advantage that no one has yet. It would make me buy their charger.
Would it be possible to simply include a couple of spacers for shorter batteries that way the springs only need to support 18650 - 26800?
I’m 100% in favor of the feature list that @Kardel posted:
It will be nice if you can add some identification to your cell (barcode/QR/RFID/etc) and a reader to the charger so we can have history of our cells (num of cycles, capacity, etc.)
power bank mode.
Here are two features I would like to see in future advanced chargers.
1. Display actual charging current
It would be nice if ACTUAL charging current is displayed during charging. For example, when a charger is set to push 2A into a battery, the charging current slowly decreases as the battery fills up. I would like to monitor that information. I find the following information useful in my current charger: voltage, configured charging current, charged capacity in mA, time, internal resistance, and temperature. I would like to see actual charging current in addition to the information listed above.
2. Improved contacts
I would like improved contacts. I like chargers that displays detailed information of charged batteries, especially that displays internal resistance. I understand internal resistance measured in most chargers are inaccurate, but it still is an useful piece of information. However, the internal resistance measured usually depends on the goodness of contact between the charger and batteries. If I squeeze the contacts for better electric connection, I usually get better IR measurements. If the metal contact that are usually used in the chargers are improved, then I think the measurements can be much more reliable.
A charger with 4 point measurement for the IR and a storage mode (3.7V). Battery size from 16340 to 26800. Cell chemistry: Li-Ion, Ni-MH, NiCd and LiFePO4.
Ooh...
Great ideas!
A quad charger that had 2 bays 26800 capable and 2 that were 16340 capable would be cool.