The making of the BLF UC4 charger: the start of a new venture, INTEREST LIST, UPDATE 3(Finalized UI and starting design)

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BlueSwordM
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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: https://secondlifestorage.com/t-Processing-Low-V-Cells

https://secondlifestorage.com/t-Does-internal-resistance-matter

https://secondlifestorage.com/t-Some-cell-harvesting-questions

https://secondlifestorage.com/t-Do-I-have-to-worry-about-Over-Discharged...

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

BlueSwordM
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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.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Joshk
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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.

BlueSwordM
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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.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Joshk
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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”

BlueSwordM
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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.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Joshk
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hasddie293
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I’ve already burrnt out of idea, but still need to say something Silly

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.

In search of the most ideal flashlight in town:
1. BRIGHTNESS
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5. Price$$$

Lexel
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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

Kindle
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KevinZA1988 wrote:
Definitely interested.

If it has active cooling, how about putting one of those PWM controlled 120mm slimline fans in the bottom of the charger? It would be quiet and effective, sucking in air at the bottom and pushing it out at the sides/top of the charger.

Ohhh nice!

OLd_gUY
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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 Smile
Lookin’ good, BlueSwordM – thank you for all you are doing to make this happen Thumbs Up Definitely on my bucket list!
OG

BlueSwordM
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@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.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

Nev
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the mc3000 charge at a lower rate when a cell is 3 volts or below & you can alter the voltage if you feel the need.

1stein
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Lexel wrote:
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

Thanks for PRO knowledge Lexel, much appreciated.

In terms of above pieces of information – does it apply also to cells so called “protected”? Can the PCB mounted inside prevent catching on fire?

WalkIntoTheLight
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1stein wrote:
Lexel wrote:
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

Thanks for PRO knowledge Lexel, much appreciated.

In terms of above pieces of information – does it apply also to cells so called “protected”? Can the PCB mounted inside prevent catching on fire?

No, protection circuits won’t do anything to prevent internal shorts from causing a cell to fail spectacularly. However, they do prevent over-discharge, which is one way those internal shorts can develop. Though, I suspect manufacturing defects to be a bigger issue for most users, and the protection circuit won’t help with that.

Rexlion
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Attention should be given to the durability of the slider mechanism. Reading reviews on Amazon for the Opus BT-C3100, I came across a complaint that the sliders were connected with glue. A reviewer of another popular charger (I forget which) said the slider springs were breaking after about a year. If I’m buying a new charger I want it to be long-lived.

azhu
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Rexlion wrote:
Attention should be given to the durability of the slider mechanism. Reading reviews on Amazon for the Opus BT-C3100, I came across a complaint that the sliders were connected with glue. A reviewer of another popular charger (I forget which) said the slider springs were breaking after about a year. If I’m buying a new charger I want it to be long-lived.

Good point. Wonder if it’s feasible to have a sliding rail that isn’t spring loaded. Instead, make the contacts be magnetic? That way there won’t be undue stress against the battery or sliders.

Need Nichia 219b r9080 Emitters? (。◕‿◕。)

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Joshk
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azhu wrote:
Good point. Wonder if it’s feasible to have a sliding rail that isn’t spring loaded. Instead, make the contacts be magnetic? That way there won’t be undue stress against the battery or sliders.

This brings to mind how a file-cabinet drawer’s back plate works. There’s a back plate that slides forward and back manually, with a lock. There is no spring. It keeps your files snug, no matter how loaded the drawer is.

light-wolff
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IMO, some tweaks to the MC3000 would do the trick, so SkyRC could be the company to work with.

BTW: I guess you all know the story behind the MC3000? SkyRC built this charger to specifications of a flashlight enthusiast. Sounds like history repeating, somehow.

xevious
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Great start. I’d also like to see a 2-cell version for greater portability.

WalkIntoTheLight
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xevious wrote:
Great start. I’d also like to see a 2-cell version for greater portability.

I worked out the probability that you’ll see anything from this project, and it turns out it’s only 2.718%.

Still, it’s fun to speculate what could be. IMO, the only thing that stands a chance of getting anywhere close to the requirements is a modified MC3000. Though, that would never get done on the budget requirement of $39-$49.

Group buys (like the recent one for the Xtar Li500S) make a lot more practical sense for a “budget” charger.

The only way a BLF charger would get done is to ask a company like Xtar to make some very minor modifications to an existing charger, and do a group buy. But that will never come close to the requirements for this project.

light-wolff
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Finally a realistic view.

Joshk
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WalkIntoTheLight wrote:
I worked out the probability that you’ll see anything from this project, and it turns out it’s only 2.718%.

That’s a very precise number. Show your math please.

amishbill
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Joshk wrote:
WalkIntoTheLight wrote:
I worked out the probability that you’ll see anything from this project, and it turns out it’s only 2.718%.

That’s a very precise number. Show your math please.


You sound a lot like my elementary school math teachers…

DIY LT1 battery wrap image. "PDF on Google Drive":https://drive.google.com/open?id=1IHIEOi1NXu868IYNCzIM7D2Ulpxchmww

Fresh Sanyo NCR18650GAs already wrapped "for sale HERE":http://budgetlightforum.com/node/69120 if you like.

Joshk
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In HS and college science they teach that only the last digit is non-precise. So if I say I have 2.5 gal of gas, it’s understood it could be 2.48 or 2.54. But if you say you have 2.500 gallons of gas, then it’s a fact that it was measured to at least the hundredth of a gallon.

So when you say “I worked out the probability” and the answer is 2.718%… that is fascinating to me.

Rexlion
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Joshk wrote:
WalkIntoTheLight wrote:
I worked out the probability that you’ll see anything from this project, and it turns out it’s only 2.718%.

That’s a very precise number. Show your math please.


Perhaps he simply asked Spock to calculate it. Wink
Joshk
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BlueSwordM, is there news on this project?

BlueSwordM
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Yeah, something like a modified RC3000 is out of the picture.

@WalkIntoTheLight, as I’ve said before, if the additional features don’t work out, then the basic adaptable voltage charging(3,60-4,20) and very low current voltage recovery will be the only features implemented.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

BlueSwordM
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@JoshK, not until Wednesday next week.

My very own high current Beryllium Copper springs Gen 3:
http://budgetlightforum.com/node/67401
Liitokala Aliexpress Stores Battery Fraud: http://budgetlightforum.com/node/60547

bmengineer
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BlueSwordM wrote:
Yeah, something like a modified RC3000 is out of the picture.

Why is that?

Find all my reviews of flashlights and more gear at www.bmengineer.com

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