Schottky diode between charger and lithium cell? 

As a science tech in a secondary school i approve this message.

Provided there are minimal casualties.😊

This is quote worthy.

Perhaps the real charger was the friends we made along the way!

@@tncorgi92 It does depend upon the casualties... 😈🤣

Damn right!!

The teachers are aiming for success in exams rather than success in life.

@@ncooper8438technically, they're teaching to pass exams, not comprehend what was taught. Makes sense, as their pay and the school budget depends upon the test results, creating a conflict of interest.

@@spvillano Goodhart's Law: "When a measure becomes a target, it ceases to be a good measure"

If it's Clive, the statue better be erected!

Tesla recommends charging their car to 80 percent. Would that quadruppel the life?

@@franzliszt3195 I don't know, probably not but maybe it's 2.3×? Specific datasheets are hard to come by so a big dose of salt and S.W.A.G. (Stupid Wild something Guess) is the best I can do.

When I first got my Y class 2 years ago Elon said charge to 90 percent; then about 6 months ago I saw on the screen of the car recommending charging to 80 percent. So Elon's statements should be taken with a grain of salt.@@matthewellisor5835

​@@franzliszt3195 yes, if you keep the lower end of the discharge above 20% SOC, 60% DoD has ~4x the cycle life compared to 100% DoD usage for most lithium chemistries.

@@franzliszt3195not really, car batteries are rarely charged up from 0%

It is good practice to have the smoke extractor next to 'The pie dish"

Especially with power supplies. The cooler the better.

That's because most manufacturers (especially those in China) want "good numbers" while still trying to keep building costs to a minimum. So they overrate their products - what is 70-80% of rated load (sometimes even less) is what should be 100%, for reliabile operation. For lithium batteries, it's not about greedy manufacturers, but the limitation of the battery chemistry it self - one can choose to charge to 4.2 V, to get maxiumum capacity out of them but realtively few charge cycles and short lifetime - or only charge to 3.9-4 V and get 70-80% of the capacity, but like 3 times more charge cycles and longer life out. The problem is when those batteries are used in products that's built to run the cells at "too high" voltage. For example cell phones often seem to charge the battery all the way to 4.35 V and shuts down (indicated 0% charge) already when the voltage has decreased to like 3.5-3.6 V. Unless they use some other chemistry than typical lithium ion (like the 18650 cells), that exaplains why they degrade relatively fast compared to in many other applications

While that would kind of work, the cell is not charged to its final voltage without the current first having been tapered down to zero. The simple explanation would be that during charging you see a combination of actual cell EMF and voltage drop across series resistances. This means that a comparator tripping at 3.9 would not result in a cell EOCV of 3.9, but rather something considerably lower

@@Kuremyr is it worth it to apply a test load every (x) minutes, idk maybe modulated by some chip, to see the voltage drop? probably not worth it if you want to make money selling an 80% charger tho lol

You can actually get some of the charger chips with different end voltages. That should be the easy way to stop charge at the desired voltage.

@@Kuremyr You end up with an iterative process. The cell voltage drops back, the charger restarts, etc. You could always resort to a supervisory processor that acts to gradually reduce the current setpoint of the charger. I also had an op amp controlled pass transistor acting as a constant voltage drop. Worked, but I never had a use for it.

@@erlendse The ones I'm familiar with are the Microchip parts. They have variants for different voltages, but all are 4.2+. If you know a part number with 3.9 or 4 I'd be interested.

I don't mind a bell or whistle as long as that's what's being dissected.

Yeah, the accessibility of these videos is what makes them so special.

I was thinking to link it up to something to monitor and graph the voltages rather than take manual readings! 😊

an old school paper chart recorder would be classy - but maybe that's just me.@@stepheneyles2198

likewise !

I as well, they are very dependable and get the job done cheap and well. Heck I even tore down a cheap solar light recently, and the charge control chip was in fact a TP4056!

Hmmmmmm??, is that you should only ever operate at 80% capacity ?????😏

@@brucepickess8097 maybe.. but i like to think of it of having a little something extra up my sleeve .. same thing. different perspectives 😁

is there a 12v version?

@@Palmit_Sorry I don't know.

@@Palmit_ Tlv431s all are set for 1.24 volts. You create a resistive divider such that the target voltage you want divides down to 1.24 volts. So you could rig it for 12V. However you need to look at the top resistor too. As when the current goes up above the target voltage the tlv431 starts to divert the current through it such that the top resistor burns off the extra voltage. This means that the top resistor can exceed its power rating and cause a fire or burn up. So you must size it correctly. Also you must set that resistor such that the minimum current through the tlv431 is 100uA and that the maximum current doesn't exceed whatever your particular TLV431 maxes out at. This varies from maker to maker. TI for example maxes out at 15mA through the TLV431 and has the TLVH431 which allows up to 80mA. Really for higher voltages you would maybe want to use a TL431 instead. It is internally set for 2.49 volts so your resistive divider changes. But then you can get to even higher currents. Asking for 12V you sound like of like you are charging a lead-acid cell. If you are, know that lead-acid batteries charge differently than Li-Ions and so the circuit may not be appropriate.

On your side

Ouch. A 1N5817 has 1-10mA of reverse leakage current. Not the best choice. Schottky's always have fairly high leakage currents (in both directions). You can make a perfect linear regulator out of a normal diode and a zener to ground. Solar panel -> normal-diode -> battery. And then zener from the diode/battery junction to ground (reverse biased of course for the zener). The zener must be able to dissipate the entire output of the panel, obviously. The reverse leakage of the zener should be more around 1-5 uA. The only other issue with using a zener is that the voltage regulation gets squirrelly below around 4.3V. So as long as the intent is to regulate to one of the standard voltages at or above that, its fine. But below 4.3V it isn't. Standard voltages: 4.3V, 4.7V, 5.1V, 5.6V, etc. -Matt

@@junkerzn7312 I learned this lesson the hard way, too focused on voltage drop & trying to get as much from the solar panel as possible on dark winter days. For more sophisticated stuff I tend to use low drop out regulators that happily work down to a few volts, either fixed or adjustable ones with reasonable output currents at least for what I need. Thank you for your comments.

@@springwoodcottage4248 It's interesting that there is this intersection between wanting to charge little lithium batteries like these cells, and real solar + battery systems that use much larger (usually LiFePO4) batteries. Charging small packs verses large ones. For any battery 12V or higher, a proper charge controller is really the only good solution. They are incredibly efficient too... 98% to 99% efficient, because they current-regulated buck converters taking a higher solar input voltage and bucking it down to charge the battery. Plus they do the full 3-stage or 4-stage charging algoirhtn, including float and load-support. Because they are current regulated, the voltage regulation is fairly poor, but the charge controller still zones in on the exact desired voltage(s) when pushing against a battery while charging it. That's why they can be so efficient. For example, take a "Victron SmartSolar MPPT 75/15". SmartSolar version rather than the BlueSolar version. The SmartSolar version has a bluetooth/phone-app support. This little charge controller is $70 and can charge 12V and 24V batteries of any chemistry, completely programmable via the bluetooth app. The only requirement is that the SOLAR input voltage by roughly +5V above the BATTERY target voltage. Which is easy since a 12V solar panel puts out 17-22V or so. (the "15" stands for maximum charging amps... 15A in this case, also programmable in 1A increments). Really, though, when it comes to charging batteries, its impossible to beat real charge controllers outside of the price.. And the cost has dropped precipitously over the last decade. Literally just $70 for a high-end MPPT now. Little PWM charge controllers (the Renogy is popular) are as low as $20 and still decently efficient. -Matt

@@junkerzn7312 We are blessed to live in the time of the renewable energy revolution where the prices continue to fall & the performance continues to rise. A tiny branch from this great tree is the use of small, often free, batteries with augmented solar to run various led sculptures & lights for much longer than the small solar cells that came with the device allow. In my cases I am running an Aldi star that had no solar as bought, for several hours a night, charged by a small (3 inch x 4 inch) approx 5 volt solar panel using just a single diode as a reverse drain preventer & a two transistor plus ldr dark detector all in a snap lid plastic box from the super market, with 3 NiMh aa cells each with a capacity of 2600 mAh. This is very efficient in the use of components & practical as it does what I want.

I've discovered that if you use a protected cell and a solar panel which is capable of more than the cell's full-charge voltage but only capable of supplying a small fraction of the normal charge current (1/20th C or less), you can charge the cell through a normal diode. With the available current being so low, the cell's terminal voltage "drags" the solar panel's voltage down until the cell's terminal voltage rises high enough to trigger the protection circuit which cuts off the charge current. I've had a protected cell from a telephone charging from a (nominally) 6 Volt solar panel this way for years, going through an automatic daylight detector which turns on a string of around 10 LED lights at night and turns them off again in the morning. I wouldn't try this with any cell which didn't have protection, though. The LEDs provide just enough illumination in my carport to light up the drivers' side of my car at night, just in case I forget to leave my outside light on so I can see when I get home after dark.

I don't like the sound of this either, I don't think it works like people believe, must have a play one day !

With 1000x the credibility.

a bigger one would probably minimize those oscillations, as it typically have more thermal mass and less Vdrop variations.

You could also use a forward biased transistor in saturation. The C-E voltage drop is only about 0.2 Volrs. Too bad germanium transistors are hard to come by these days. The voltage drops is a little less and as current heats the junction, the voltage drop is even less. With the TP4056 limiting current, thermal run-away would not be an issue, but the heating of the germanium would allow the battery to get more current when it is discharged and then tail current off more as the junction cools when the battery nears full charge.

The problem is that if the current nears zero, the diode drop also nears zero. I was thinking about a 3K9 resistor over the cell (1mA) so the voltage drop never comes under .2V.

Sadly this solution is not optimal. So still hoping for 4.0V or 4.1V variant of this charge chip which will never happen - at least not for this ultra low price like TP4056

Can you please explain this in more layman's terms

@@keylanoslokj1806 Essentially, Lithium battery chargers detect "end of charge" via cell voltage. Schottky diodes have a lower "conduction" voltage drop than your "normal" diodes, and this small voltage drop adds to the battery voltage, so when the charging circuitry "thinks" the cell is fully charged, it in fact isn't quite fully charged. This very slight under-charging can really extend the lifespan of lithium cells, so it's a useful (and cheap) way of keeping your cells going far longer! Hope this helps!

Note that some cheap flashlights rely on battery impedance to limit current through the LEDs.

@@bigclivedotcom Thanks for the info. That is probably the case here, because I don't really recall seeing much of anything inside. :)

You don't keep them hooked up for storage, thats just BS the manufacturers will give you a shelf voltage to charge (or discharge ) to for storage and its typically 3.5 ish not overly critical and of course cheap cells with high internal resistances will self discharge quite quickly.

@@andymouseI dont think hes suggesting you 'should' more that you 'can' (as long as the power supply is below the fully charge voltage, as as soon as the power supply voltage matches the battery voltage there will be no potential difference, and then no current will go into the battery, so it wont be charging anymore. Although you shouldn't do this in my opinion, as if the cell has a high internal resistance, or gets warm when charging, has dendrites etc, it will sit there burning off power in the form of heat, which will leave it constantly charging = constantly getting hotter and hotter until it goes nuclear. Its in my opinion the common failure mode of most cheap Chinese battery packs (that lack thermal protection, cell level voltage monitoring). And why its important in my opinion to never leave Li batteries charging unattended. You never know if a cell has gone bad and if there is sufficient protection to stop it going nuclear.

It seems we agree but people shouldn't chime in with BS regardless of 'should' or 'can' :)@@ratgreen

"Electro Curious" hmmmmmm, is that for persons of a persuation who enjoy mutual coupling as in electronics, electric power and telecommunication, coupling is the transfer of electrical energy from one circuit to another, or between parts of a ........ Ooooo, Errrrrrrrr.😏

Talk to Clive about other things he's 'Curious' about !

When I go into the electronics store, they always put the vintage non -SMD resistors and transistors in a plain brown paper bag. So considerate of them. Once I bought a filament bulb rather than a LED and the young lass behind the counter went bright red and didn't know where to look. So embarrassing. @@brucepickess8097

My local electronics store has a non SMD component section down the back behind a curtain. They put the resistors and transistors in a plain brown paper bag so as not to embarrass me. Recently I bought a filament type pilot bulb instead of a SMD dual color led. I know some people say it's not natural and extravagant. The young lass behind the counter turned bright red and didn't know where to look. @@andymouse

My local electronics store has a non SMD component section down the back behind a curtain. They put the resistors and transistors in a plain brown paper bag so as not to embarrass me. Recently I bought a filament type pilot bulb instead of a smd dual color led. I know some people say it's not natural and extravagant. The young lass behind the counter turned bright red and didn't know where to look. @@brucepickess8097

You would :)

@@andymouse Thats alright then... I guess when it comes to batteries people always wanted all the capacity available but for things left on charger all day except for the 5 mins you need them perhaps 80% is good enough. The other point that I didn't make is that its also better not to charge them at 1C just because you can. The lower the better but lithium don't seem to mind the charge rate too much unless they start to heat. So 0.5C will probably make quite a big different bit 0.1 not much better.

Kinda hard to trust what you are saying when you refer to 3.8V as being 25% state of charge for a Li-ion battery.

You could use an lm317 adjustable and either use it to current or voltage sense

The charge will go anyway, the resistor does not make any sense the voltage drop on it will be too fast, a small capacitor is probably a better idea.

I tried the inverse Parallel diode and a resistor and neither made a significant difference.

Mine too, I have kept it at 80% for the last 6 years and it seems to be in pretty good condition