The making of the BLF UC4 charger: the start of a new venture, INTEREST LIST, UPDATE 7 (Well, ramping stopped :/ )

It should be easy to use, like using a hobby charger (which has already the features this project aims) but this time having 4 individual bays.

Enable it to keep four cells in trickle charge indefinitely and put a floody LED with a smart (TK) user interface on it — so it becomes a grab-and-go item for those of us in earthquake territory.

@contactcr, no problem. Just upped the discharging current to 700mA. 1A could be possible, but you’d have to limit discharging current to 1A/2 bays to help with heat dissapation.
Also, putting a small aluminium heatsink on these resistors would help a lot.

@hank, that is easy peasy. Just set the charging voltage to 3,9V, and be off with it. Charge it normally up to 4,2V once you need it.

I love the idea of a perfect charger. I have to use a Folomov A1 to charge my Wuben 21700 that is 75.1mm. Could this project somehow ensure that the longest 21700s fit?

Yes, absolutely.

What is the absolute longest 21700 that exists?

Is it that 21700 from Acebeam that uses a buck-boost converter to charge USB devices and charge itself?

I was thinking of something plug-and-play.

The charger recognizes the chemistry and length of the cell being charged, and chooses a suitable charging current.

(I don't know if that's possible.)

That is possible, but is slightly harder and more error prone.

Chemistry is just based on the internal resistance analysis, but it has to be conservative. Currently, the C4-12 that I have likes to go at 3A on my 30Q during automatic charging, while I would prefer 1,5A at max.

Length would be slightly harder, but would require additional hardware.

would be cool if it did it based on length + resistance so high current 18350’s dont get overcharged but still allow like a VTC5A to be fast charged

How about a BLF firmware for the MC3000?

Wouldn’t that cover just about everything you’ve asked for?

Yes, but not in this case.

The MC3000 doesn’t have:

- Support for long 21700 cells.

- USB data out.

  • The higher conductivity brass contacts.

And other miscellaneous stuff that I haven’t included.

The design of the MC3000 isn’t also optimal. I prefer the C4-12’s design.

And it’s also rather expensive.

Okay, cell length might not need to play a factor if internal resistance is being analyzed.

I told you I'm not a charger expert.

definitely watching this one, looks very interesting. :+1:

I would refer the option to custom selecting cell chemistry, type, size, and amps-charge rate when required, ( but have a auto 18650 LiIon & AA NiMH as standard automatic with a default charge rate, ( but also customizable. Also woudl be good to have one of the charge Bays adaptable with an output port, (the charger would be great with at least four bays) that output port would have leads for charging wired cells like square LiIon and other packs, large cells like 32650s, (i have 7 of them) and even have the lead-adapter with tiny magnetic positive & negative connectors so they can snap to everything in cell size from a 10180. I know cost may be an issue for that, but a true “universal” charger needs to be able to charge every type of cell at every amp range selected, and connect to them easily. One great single cell charger i really like that can charge nearly every size cell is the Olight mini USB magnetic charger, (I have 5 of them) ( that senses the polarity and charges them, But the only issue its set at one charge rate only.

My interest is piqued! Consider me interested.

Added adjustable automatic current feature.

Perhaps I should do a UI chart for this. :slight_smile:

Longest 21700 i have is Rofis RF21700 at 76mm.

Added to the list of features.

interesting
I can ask some manufacturer

What an awesome idea. Yes, yes, yes, we need BLF ultimate charger :+1:
What about BT App? Since SKYRC is on the mouth, they are also (hmm…) experienced in incorporating BT module and Application. But I must say the one going with MC3000 is kind of primitive (sorry SKYRC). The good one could shake the market if the price is “friendly”.

(definitely subscribing this thread :smiling_imp: )

I’m all in. All my chargers are at most mediocre. I’d like to buy a high end one but there’s nothing that really suits my taste.

A few comments:

  • 100 mA minimum current is quite high for 10180, 50 mA would be better.
  • making the 2 outer slots larger (deeper, with a larger slot cutout diameter but without larger width) would enable 32650 support
  • 4.35 V cells are rare nowadays but I don’t think it would hurt to enable the top voltage this high
    • this could possibly be also used to overcharge regular cells to 4.2xV for that tiny output boost…with x depending on the precision of voltage measuments
  • I see no mention of capcity measurements. I suspect this is an omision. :wink:
    • discharge current should have high adjustment range, ideally the min would be 100 mA or so for 10180 and max 10A+ to test powerful cells
    • adjustable discharge terminal voltage would be useful as well, some would like 3V, some 2.5V, some probably different numbers as well
  • ISDT may be a good maker
    • they make good chargers
    • their UI rocks
  • USB PD input would be nice