Tesla 21700

The real model name of this cell is: Sanyo NCR21700A which has a nominal capacity of 5000mAh and a continuous discharge rate of 3C, therefore 15 Amperes in continuous discharge. Tesla does not manufacture any cells themselves, in the Tesla GigaFactory equipment and personal from Sanyo work to produce EV cells under contract with TESLA, so Tesla do not manufacture themselves, itā€™s a kind of outsourcing home. This cell has been rewrapped for some time by Vapcell, I give you the link below. The only major defect of this cell is its positive pole which is recessed posing some contact problems in the 21700 compatible device.

http://www.vapcelltech.com/index.php/Show/index/cid/41/id/57.html

It seems like Vapcell has all the good batteries on the market in stockā€¦.

There is no sanyo NCR21700A.
There is a sanyo NCR20700A which is 4000mAh or a Panasonic NCR21700A which is 5000mAh.
Maybe youā€™re getting confused because panasonic owns sanyo.
Everyone already knows panasonic is making teslaā€™s batteries btw.

Also, just as with the ā€œ3500mAh 18650ā€ cells the real world performance is always less, you will not get 5000mAh at 3C discharge, MAYBE at 0.2C.
The real world capacity will be somewhere between 4500 and 5000.

It is Panasonic that produces the NCR21700A and not SANYO, but there you quibble because they are the same two brands, we can say that it even merge, I knew perfectly that SANYO belongs to Panasonic, except that Sanyo remains independent on many of its production and model, otherwise there would be no Sanyo NCR20700A, Sanyo NCR20700B and Sanyo NC2070C, and they are well stamped Sanyo and not Panasonic. For the NCR21700A, wholesalers sites that provide Vapcell with this clearly denominates ā€œPanasonic NCR21700Aā€ but hey have you listened I do not know what Iā€™m talking about, while I was wrong thatā€™s all, the mistake is human , no?

For the history of the 3C: I never said that the NCR21700A gave 5000mAh with a continuous discharge at 15 amps, I just gave his technical specs official ie: nominal capacity of 5000mAh and continuous discharge current maximum of 15 amps is 3 times its load so it gives 3C in C-Rate calculation, when I write something at least read it correctly, thank you.
PS: I just learned the only cell that has a common production between Panasonic and SANYO is the NCR18650GA, and thatā€™s all, if in the other models of these two brands, you see two different brand names for the same model is simply a mistake.

The average internal resistance of the 4 NCR21700A cells I own is about 12 milliOhms in ACIR-1kHz (Tested with YR1035 Internal Resistance Tester). How much did you get on your measure, just out of curiosity?

A bit triggering that vendors like Nkon sell them cheaper than Vapcell in their own Aliexpress store. :frowning:

BTW is it ok to put a big magnet on the positive pole of the battery or does this add significant resistance?

This is perfectly normal, Vapcell applies retail prices to individuals / public in their store, when Vapcell sells to NKON, they make them wholesale prices and NKON purchase large volumes by contract of regular supply, therefore NKON can afford to sell Vapcell batteries cheaper than Vapcell themselves in their Store, there is nothing illogical on the contrary, it must be attractive to the customer, right?

Yeah, nothing wrong with that, just pointing it out.
Donā€™t take it personally or anything.

Donā€™t have anything to measure the internal resistance, Iā€™ll try to get my hands on a large resistor to calculate it.

So I did a discharge test at 2A using my new hobby charger and got 4630mAh down to 3V. unfortunately it doesnā€™t let me discharge any lower than that :frowning:
Consistent with the results form this test:
Still havenā€™t received the battery discharger I ordered from banggood, but when that gets here I will do more tests.

Promising results, higher Wh/L and Wh/kg than any 18650.
Iā€™m curious to see how it compares to the LG M50 and samsung 50E.

In this case, you will see the Sanyo NCR21700A is the most efficient (discharge / capacity) in this range, then come the Sony (finally Murata, lol I still have trouble with this brand name) US21700VC7 which is very close, then the Samsung 50E much less powerful than the two previous ones (at the same time the two first ones have maximum continuous discharge of 15 Amperes, the Samsung 50E him has 9.8 amps officially) and lastly comes the LG M50 but which does not fare too badly for a cell with a maximum discharge of 7.35A (1.5Cx4.9Ah). In short, youā€™ll see ā€¦

Hi Enderman and HydraXX -
I ordered one of the Chinese load calculators (eBay) and it must have been a seconds - because everything was off on it. The current was off, and wattage was off, and even the time clock was off. The only thing accurate with it was the voltage. They had not bothered to calibrate it and I could not find how. It came with no instructions and could not take the 150W advertised load - and pooped out (error) at about 90W. It was constant current. But without the Wh meter working, it was useless. So beware.

I have read elsewhere that the Tesla 21700 is rumoured to be at 5.75 Ah. But your report is the first I have seen with a real cell, and not just guestimates. I would be rather surprised if it is at 5.75 Ah. On the other hand pls. note that your charger/discharger may not be so accurate. I have one that looks similar to yours and it consistently underreports the discharge by about 10%.

I am also in Vancouver - so may I ask what kind of project are you working on? I am trying to electrify a small airplane, and find todayā€™s L-ion to be somewhat short of desire. If the Tesla cell does not increase capacity by 10 or 20%, we are truly hooped. The NCR18650B came out IIRC in 2013. And there has been no off-the-shelf improvement for the gravimetric energy density? So depressing.

I bought this exact discharger which got a good review from one of the battery and electronics experts on this forum :slight_smile:

Itā€™s 5Ah, this test is accurate:
They are the exact same cells I have.
I still havenā€™t received my discharger yet but I have a new hobby charger which discharged the cells down to 3v and got 4600mAh at 2A which is in line with the test linked above, so Iā€™m confident their numbers are correct.

I build mainly flashlights and remote control vehicles.
The improvement is at most a few percent, not anywhere near 10-20 unfortunately.
Hopefully in the future they can get closer to the theoretical 300wh/kg

18+ battery content warning. Still havenā€™t made it through this whole video but it is interesting. Especially, about why he thinks Tesla is interested in Maxwell Technologies. Around 12 minutes he starts talking about Maxwellā€™s dry coating electrode process that would eliminate a production speed limiting drying oven. The process would also replace a particularly nasty solvent with something more easily handled. All of which decreases manufacturing cost. While electric cars wonā€™t entirely replace gasoline vehicles for various reasons, there is a tipping point where the decreasing cost of batteries makes them comparable in cost to a gasoline car. At which time paying around a 1/3 of the cost per mile to drive becomes a very attractive option. He is also developing what he calls ā€œselfish solarā€ using entire Tesla battery packs. Spoiler alert. It is still cheaper to buy electricity from the big electrical companies. But, there are some applications out there where it starts to make cents.

:+1: Valuable videos. Thank you very much for sharing.

ā€œWhile electric cars wonā€™t entirely replace gasoline vehicles for various reasons, there is a tipping point where the decreasing cost of batteries makes them comparable in cost to a gasoline car. At which time paying around a 1/3 of the cost per mile to drive becomes a very attractive option.ā€

And then this will be when the next ā€œtipping pointā€ is your Local, State and finally Federal Govā€™tā€™s will issue a ā€œRoad use Taxā€ to make up the lost fuel tax for road upkeep and construction.
Already happening in some states.

Say what you want about Govā€™t. They may not be good at using your tax money efficiently but they are Very Good at collecting it :slight_smile:

PA has especially a lot to lose with the worst total gas tax in the country at $0.52 per gallon. Even at that rate an electric vehicle owner would still save money per mile. But, to your point they may raise the tax to the point you were typically spending to drive a mile. It will be interesting to see how they spin that they still need emission sticker revenue.

For the most part you need a garage and a second car so youā€™re not giving anything up. The plus is you spend less money per mile, no need to wait at a gas station, have instant torque, and you spend less on emission stickers, brakes, and oil changes. Notice I left out anything about saving the planet. To me the wrong marketing strategy. If you want to produce less CO2 walk to a grave yard with a shovel.

Still havenā€™t made it through the whole video. But, I did get to the point where he says he finds nothing revolutionary with the new cells as far as energy density.

His charging method is all messed up, and he doesnā€™t even notice. Heā€™s got a 1.2V drop @10A of which 0.1V is over the shunt, the rest must be leads and contact resistance (a magnet? Why?).
Because otherwise, he could just have let his PSU do the CC/CV thing without constantly bumping the voltage up and down (and no, you can not move the CC/CV point around with a fixed CC/CV scheme, itā€™s determined BY THE CELL). Yes heā€™d still have to compensate for the shunt at the end of CC but thatā€™s it.
I hope the man is not an EE because that would be shameful.

I believe the reason he adjusts his PSU voltage is because he needs to keep a constant current. If from the get go he sets it to 4.2V, he will exceed the CC amount by far and damage the cell. So he sets it at letā€™s say 3.8V and keeps on rising it to 4.2V in order to keep the current constant at the proper C rate. The shunt and ohmic losses do not matter. Because once the PSU is set at 4.2V and the cell voltage approaches it, the shunt and ohmic losses can reduce the current fed to the cell (which is a good thing), while it will never reduce the end voltage of 4.2V.

For Lion, once you are above 4V, you cannot charge it at the continuous C charge rate. You must reduce the rate or you will damage the cell. At 4.15V, it would be an error to charge it faster than 0.2A, for example, as it can create dendrites.

Of course if the resistance in series (shunt plus losses) is high, then in order to reach the CC rate, he may have to increase the PSU voltage ABOVE 4.2 to get the desired current. But once the cell voltage approaches 4.2V, he needs to reduce the voltage from 5V (for example) to 4.2V. It appears he is doing the right thing.

Waitā€¦did I read it cost less to drive an electric car?

Quick, tell me how much it costs to replace a battery. No ā€œit will costā€ in the future, right now, how much?

A BMW dealer had an electric Smart car. $8,000 for a 2015 car that cost $33,000

I asked the Benz dealer how much it would cost to change the battery. All I got in response was a huge run around and no quote. The service manager who I know since ā€™95 says about $17,000.

Here is an exampleā€¦.Two year old carā€¦original price over $32kā€¦ā€¦asking $11.8. It will probably go for $10Kā€¦ā€¦ā€¦ā€¦ā€¦Two thirds of the price lost in three years.

https://www.autotrader.ca/ico/smart/fortwo%20electric%20drive/burlington/ontario/5_42375332_20120802151526874/?showcpo=ShowCpo&ncse=no&ursrc=pl&urp=3&urm=3&pc=L5B%202R9&sprx=100

Tell me again, how cheap are electric cars to run?

Battery replacement, unless under warranty, just isnā€™t done. It would be much like comparing it to the likelihood you would buy a brand new motor and transmission. Unlike a cell phone, ev batteries are designed to last quite a long time. What is to be expected is there will be a loss in capacity. In such small production run cars the battery is the limiting factor part. If a manufacturer made 10,000 battery packs its going to try to build a car around nearly every one of them. They would keep a few for warranty purposes and the other cars would simply be totaled over being repaired.

Large incentives drastically effect resale value as well as peoples apprehension of the unknown. Which is partially the case in your example. But, there is also that the Smart is not a good looking car, has never sold well in any of its variants, and is completely out of place in the states where larger suv and crossovers are favored.

The efficiency improvements in gasoline engines are slowing. If you live in colder climates the wasted heat can be used but it is mostly pushed out the tailpipe. In contrast, an electric motor is several magnitudes more efficient. This is why you can drive several miles on a kilowatt. The encouraging part is while gasoline efficiency has stalled, ev are steadily getting better and cheaper. Actually, there are many innovations in the works that will revolutionize how we get around. Torque vectoring seems very interesting.

Electric vehicles are in the early stages of technology adoption. There not a one size fits all solution, but they do offer many advantages that a gasoline car could never attain. And things will change rapidly as the technology improves and people adopt them.