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

Option 2: The Ultimate BLF charger. Aluminium body with a 100mm fan inside, and 60W discharging compatibility.

Ditto for option 3. :wink:

Both USB PD and DC are standards.

I have a powerful universal DC PSU, so with a jack I don’t need a separate charger.
I don’t have a USB PD one but since it’s standard I don’t need one included. I’m likely to be buying one that is better than whatever gets included here anyway at some point.

I think that it would be nice to offer a variant without a PSU. Especially with USB PD.

Is this charger going to support 10180 size batteries or not? Just curious.

It looks to my semi untrained eye it would be pita to create slides & springs to accommodate battery sizes from 18mm to 78mm in length without sacrificing reliability somewhere along the way. :question:

If the fan is powerful enough it can have a built in hovering feature.

@teacher, never talked about 10180 support.
It would be nice to support, but something like a small charging module sold separately that can connect directly to the USB port would be better.

@Th558, would be nice, but the power supply would need to be upped to 160W.

@ BlueSwordM
Thank you for the verification. I had seen a few mention it like it was a done deal for 10180 support & was curious since I could not find where you had mentioned it.
Personally I saw no need for it at all.

remove that dangerous feature,
nobody really wants to make a potential thread for thermal runaway cell, recovering over discharged lithium batteries
such a cell has to go to the recycle bin

for NiMh it may be good, but definitely not on lithium

I agree with Lexel. I’ve read dendrite crystals can form inside a lithium battery that has been over-discharged and permanently short it out. Or short it out soon after.

How is that a dangerous feature?

Here’s how it’s usually done:

If between 2,0-2,5V, then charge at 100mA until the cell reaches 3,2V.

If between 1,0-2,0V, charge at 50mA until it reaches 3,2V.

If below 1,0V, charge at 25mA until it reaches 3,2V.

Most thermal runaway scenarios in relation to overdischarge happen because at such a low internal voltage, a lithium-ion cell has massive internal resistance, and the low voltage potential means parasitic reactions take place, robbing the cell of capacity.

However, when charging at normal current levels, the cell bounces back to normal voltages, but not before internal damage is sustained, and parasitic *chemical *reactions are pushed at a massive rate, resulting in elemental lithium plating, and a thermal runaway can occur.

In most cases, this doesn’t happen fortunately. What instead happens is that the massive voltage spike robs the cell of a lot of capacity.

That’s what I noticed back in late 2017: by charging cells back up at very low currents, my 18650/20700/21700 recovery cell yield had gone up tremendously. I did some research, my own testing, my own research, and came to the conclusion.

It not only improved the yield of used cells massively, especially powertool cells, but the percentage of higher capacity cells being recovered got up by a nice margin.

It’s also a very safe method of recovery. It does need an additional step in software to make the charger stop charging if the voltage stops rising after a predetermined period of time.

Some more stuff from other members: Processing Low V Cells | Second Life Storage & Solar

I wouldn’t want to implement a feature if I hadn’t tested it before myself, and a lot of other people for a long time.

It’s probably not an issue 99% of the time, but once you sell 1000 chargers, that’s 10 issues. It depends on your trust of a muggle, and opinion on the risk. I’d advise against taking the risk. It’s your choice though.

Ah, that’s where it comes in handy.

The main customers won’t be only us, and some muggles.

It’ll be a lot of people on other forums, like SecondLifeStorage, who already have tested that feature on hundreds of thousands of cells.

If you are going for it, can I at least convince you to add a prompt when the feature is activated that asks “Accept risks? Y/N”

The answer would be no… way I wouldn’t accept that!

I mean, low voltage recovery is great and all, but the preset settings are only good for 18650 cells and larger.

So, for smaller cells, I have to implement a warning.

:+1:

I’ve already burrnt out of idea, but still need to say something :stuck_out_tongue:

Improve font,symbol and styling…better dimmer backlight lcd. no seen brighter beam or so… You know when you look at it, you will be amazed by it… ok that it.

No matter how you try to reactivate a cell the chemical reaction starts if the voltage is too low
the build up of the crystals is non reversible

If the cell is then used again it can start develop an internal short anytime, usually under discharge or quick charge
There are enough cell failures of vapors because of over discharged cells, they can literally go off in your pocket or face

The Worst thing that is most likely to happen with flashlights is you are not at home or in your car and that cell starts a fire

Ohhh nice!

Just want to say that the enthusiasm and knowledge of all involved in the discussion of this project is the reason I finally decided to get off my butt and join BLF :slight_smile:
Lookin’ good, BlueSwordM - thank you for all you are doing to make this happen :+1: Definitely on my bucket list!
OG

@OLd_gUY, thank you.

@Lexel, I agree.

But the internal lithium plating most occurs during normal recharging.

See, at usual voltages, lithium plating can’t occur without extreme discharge currents(massive voltage drop).

However, at low voltages, it can become a problem since the reaction isn’t inhibited by the internal voltage potential.

It’s not an issue when sitting in storage at average temperatures. But, when charging back up at normal current levels, the huge current surge can induce a very short burst of lithium plating crystals, like what happens at high currents with tin whiskers during electroplating.

It’s why I’m planning to make this feature optional: if a cell below a voltage of 2,40V is recognized, you’ll have to proceed with charging manually.

TLDR: I’m listening to JoshK.