some questions for SunKing, and anyone else on lithium battery technology

[Sunking]

Hmm, Forth edition ... I never got into Forth, my programming ceased after BASIC, Fortran, PL/1, and C. <big grin>.

You are welcome. If al you are interest in is Lithium batteries, only two chapters to cover. Enjoy.

[gbynum]

Forth Edition will ...

Hmm, Forth edition ... I never got into Forth, my programming ceased after BASIC, Fortran, PL/1, and C. <big grin>

A HUGE THANKS! I'll enjoy skimming the book, but it may take more than a month.

[Sunking]

One more huge treat for you. Everything there is to know about all batteries. This is the 3rd edition so it is free. Lithium is in there and the info still applies. It is the Mother Load of a book. I call it THE BATTERY BIBLE. It will take you a week to read all 1500 pages. Months to get it to sink in.

Forth Edition will cost you $150, so enjoy the free 3rd edition.

SK

[Sunking]

thanks!

You are welcome. Check the other link I gave you. I added more content for you in my last reply. Read David's site and I am sure you will have some excellent questions.

[gbynum]

my bad, try again.

thanks!

[Sunking]

Sunking, that link is to your system's filesystem ... C:/Users/Dereck/Downloads/energies-09-00900.pdf ... can you give me one that's accessible from outside? TIA, George

My bad, try again. I fixed the link.

Here is a bonus from a very good friend of mine David Andrea. Another White Paper on SOC. The bonus is once you get to that site is a wealth of information on Lithium batteries. Surf around, take your shoes off and stay awhile. He list every Lithium battery and every BMS there is with a ton of white papers and tutorial videos . You can spend a couple of days. David is an avid custom EV builder and BMS designer. If you can soak everything in David provides, you are well on your way.

Just remeber SOC is basically an estimation or WAG. David makes it at least a education and gets you in the ball park WAG

[Sunking]

Hogwash. You were banned from posting links because they were nearly all greenwash rubbish and were lowering this site's trust rating. You were warned for weeks/months about it.

Karrak cannot take a hint he is not welcome here. Just ban the SOB and be done with it.

[gbynum]

If you really want to dive into it, here is a good white paper on the subject.

Sunking, that link is to your system's filesystem ... C:/Users/Dereck/Downloads/energies-09-00900.pdf ... can you give me one that's accessible from outside? TIA, George

[Mike90250]

... sorry about not posting a clickable link, for reasons that are beyond me I am not allowed to post links.....

Hogwash. You were banned from posting links because they were nearly all greenwash rubbish and were lowering this site's trust rating. You were warned for weeks/months about it.

[Sunking]

Thanks Sunking. So my original question; existing charger cuts off at 4.15 or so ... given that I don't need full energy stored, would I be better off to stop charging at 3.9 or 4.0 ... assuming I can determine how to do so?

You are on the right track. LFP is the hardest to find because the charge discharge curve is so flat. Not so with any of the othersexcept LTO.

Do you have the means to measure AH Discharge Capacity? Example many of the RC Hobby Chargers can charge or discharge any battery type. You can see what goes in, and what goes out. You would start by fully charging and then discharge and measure maximum capacity at 4.2 volts. Then Recharge to 4.1 volts and discharge, and so on until you get to where you want.

Another way is you charge at 4.2 volts but terminate at a higher current than C/33. Example say it is a 10 AH cell instead of terminating at .3 amps, terminate at say 1 amp. Then do a discharge test to see where that lands.

Assuming you cannot do a discharge test, you can use your flashlight and a timer. Fully charge it. then discharge in the flashlight until it goes dim and clock it. Lower the charge voltage a bit, repeat. If it goes 120 minutes on a full charge, you are looking for something like 100 to 110 minutes. If the flashlight is a single cell model, you do not have to worry about over discharge especially on LEd models. The driver will shut off before any thing can happen, You only worry when you have more than 1 in series. It takes another stronger battery to drive the weaker one into reverse polarity.

So you are on the right track and just have to experiment a bit.

If you really want to dive into it, here is a good White Paper on the subject. You can cut to the meat on pages 9 and 10 graphs. But I can tell you from experience on a 3.6 vpc cell you charge until saturated @ 4.1 to 4.15 volts. That will get you 85 to 95% range. Another clue is Nissan Leaf battery max charge voltage is 4.1 on NMC batteries. No commercial EV manufacture allows the customer to fully charge a battery. They would go bankrupt if they did. They only time they allow it is at the end of life to get at that last bit of capacity they have been banking and saving for the end of life. Tesla did it already on older Roadsters and released the last top 20%. EV's operate 20/80 to 10/90 range. The golden rule is to stay away from the knees of the charge discharge curves.

[gbynum]

Thanks Sunking. So my original question; existing charger cuts off at 4.15 or so ... given that I don't need full energy stored, would I be better off to stop charging at 3.9 or 4.0 ... assuming I can determine how to do so?

[Sunking]

I am not going to bother looking up the actual part number to tell you what type it is. I will tell you how to figure it out yourself. The key is Nominal Voltage

3.2 volts = LiFeP04 aka LFP or Lithium Phosphate. Charge 3.6
3.6 volts = LiCoO2 aks LCO or Lithium Cobalt Oxide. Charge 4.2
3.7 -3.8 volts = LiM2O4 aka LMO Lithium Manganese Oxide. Charge 4.2
3.6 - 3.7 volts = LiNiMnCoO aka NMC Lithium Nickel Manganese Cobalt Oxide. Charge 4.2 , What a mouth full of alphabet soup.
3.6 volts = LiNiCoALO2 aka NCA Lithium Nickel Cobalt Aluminum Oxide. Charge 4.2 volts
2.4 volts = Li4Ti5O12 aka LTO Lithium Titanate. Charge 2.85 volts. These are the monsters of Lithium batteries that can last up to 10,000 cycles. They have low Energy Density (wh/Kg) as indicated by the voltage, but the highest Power Density W/Kg and W/L. These cells can be charged and discharged very fast, and the safest of all battery chemistries. Almost no channce of thermal runaway.

Here is your takeaway. Does not make a lot of difference what type it is from a manufacture charging POV as there are only 3 voltages to take note of to 100% SOC: They all Charge at C/2 and Terminate C/33. Note some can be charged faster than C/2 up to C5. But C/2 and lower is safe for all types.

2.85 for LTO
3.6 volts for LFP
4.2 volts for everything else. LCO,LMO,NMC, and NCA

Hope that helps you get started. Those batteries are either LFP, or NMC. So all you need to know is what voltage of either 3.6 or 4.2 volts.

[gbynum]

Thanks! Staying off the solar panel subject (do the mods care ... this is a battery subforum), my next step is to understand protection circuits. I do visit candlepower but find more technical info here, more emotional there ...

When I hook up my DAS to the assembled cell terminal, the protection circuit is in the charging path ... how much drop is attributed to it? Time to use Google.

[sensij]

According to a thread over in Candlepower forums, that Nitecore battery is built around a DLG N18650 2200 mAh cell. Based on the information available from DLG, that probably means NCM chemistry, under the NMC heading on batteryuniversity.

http://www.dlgbattery.cn/en/upload/2016-08/12/DLGyuanzhuxing.pdf

[gbynum]

So be specific. LTO is around 2.5 vpc, LFP 3.3 vpc, LCO 3.6, and LMC 3.7.

Is LMC what BatteryUniversity calls NMC?