Sodium Ion 18650 Battery Discharge Test

First test of a sodium ion battery, charged to 4.1V and discharged to 1.5V. Did the 18650 cell yield the full 1500mAh capacity. What does the discharge curve look like? Note: these cells contain no lithium.

[bigclivedotcom]

I didn't even know they were commercially available yet.

[oddstr]

I've got a hold of the datasheet for these batteries from the seller, recommended charge profile is as follows;
Constant current of 0.5C until 4.1V, constant voltage until 0.05C.

Cycle life test is done with the same charge profile, except for a lower cutoff voltage of 4.0V.
80% or better capacity after 3000 cycles.

Max charge and discharge rates depend on temperature, most interesting for me is charging down to -10°C at 0.2C, and discharging down to -30°C (also at 0.2C aka 300mA) – with some reduced capacity.

[oddstr]

The usable voltage range looks perfect for Pi Pico projects! (1.8-5.5V input range on VSYS)
2V looks like a reasonable "help my battery is empty" voltage, while still running for a while after that :)

[borayurt]

I actually like the way that graph works, it is good to see a 15 second real time data, otherwise we wouldn't be able to see any small fluctuations if they were to happen. Also, it is easier from a coding perspective, get 15 seconds of real time data, average it, then add it to the accumulated data.

[BRUXXUS]

Pretty cool to see some actual testing with one of these cells! For anyone interested, I cam across, and use a rather useful little TI boost converter IC with an input voltage range of 0.5V-5.5v which could work nice with how low the voltage gets on these sodium ion batteries. It's the TPS61022. Output voltage of 2.2-5.5V, so it's really useful for USB stuff, or, what I use it for, ws2812b LED strip projects. :)

[rilosvideos]

Thanks for the test. I wasn't aware that these Na+Ion cells are already available on consumer level, but 5, 70 Eur for one 1, 5 Ah Na+Cell is quite expensive, given the specs with low capacity and wide voltage range. Thats definetly a PRO for the LiFePO chemistry that the voltage is very stable at 3.2V instead of 4.1 ... 1.5. You will always need a converter to adapt for voltage change for a specific application ...

[oskhar]

Great Video! Just what i wanted to see :)
I saw them on aliexpress, too, but i thought they are just LFP-Cells labeled as sodium ion.
But thanks to your video we now know, that they seem to be real sodium Ion cells! Very nice!

[FyJonas]

I may be a nerd but this is incredibly exciting for me! I´ve been looking forward to sodium based batteries for a few years now and you provide the first insights in private persons having access to them! Been subscribed for a few years now and you don´t disappoint in bringing up up and coming electrical technologies available for the consumer market. Thank you Julian!

[blg]

Hi Julian, it looks to me that you actually undercharged the cell with this algorithm and that is why you haven't registered the full capacity. The reason I think that is that your CV phase of charging was terminated abruptly after a too short time. If this cell's behaviour is similar to a Lithium one then once you reached the maximum voltage (in this case 4.1V) the charging should continue (in CV mode) until the charging current drops to about 0.01C. Your charging stopped at about 0.8C, way too early. And there is quite a bit of extra capacity that can be added at that phase. Am I barking at the wrong tree?

[AlpineTheHusky]

I think the charging stage was stopped a bit early. The Cell was still drawing 800mA and that might have offset the voltage quite a bit

[matambale]

The reviews are in: "Single handedly the most exciting battery discharge testing video since....well the last one Julian did"
(In earnest: highly informative, thanks)

[nailuj]

thx you, you are the first of testing na ion battery

[NoelBarlau]

Really a great demonstration. Thanks so much for sharing. Looks promising so far, and I'm sure there are many smart folks and lots of industrial capital working on improving power density as we speak.

[herrvonberg]

Very nice test, i was waiting a long time for a review like this so thank you. For a 1C discharge this is a good result normally lithium batteries are testes with 0, 2C discharge rate or lower for capacity tests. as we can see there ist not really a benefit discharge this SI cells below 2 volts. A test under freezing temperatures would be really interesting😅

[wrefk]

1500mah is way better than I would have expected. 1500mah nmc is still pretty popular, and lifepo4 that I've seen are 1100mah.

[hoggif]

That was interesting. I had not realized those are available already. Unfortunately capacity of 1.5Ah is still far behind of 3 to 3.5Ah that lithiums have nowadays easily.

[marcusjenkins]

A LOT more interesting than watching paint dry. The constant voltage drop during discharge will help in metering the state of charge. But it looks like almost all applications will want some sort of buck / boost circuit to cope with that mahoosive >2:1 charged to discharged voltage.

[roysigurdkarlsbakk]

Thanks! Quite interesting! Btw, people that say watcing paint dry is boring, never owned a 3d printer…

[francoisguyot]

Wonderful! I was very curious about how to charge-discharge these new cells. So you get about 90% of the specified capacity from going to 4V down to 2V while discharging at 1C. If you stretch the CV time till the current drops to 0A and stay there for another 10 minutes, I bet you can actually reach the specified 1.5Ah, provided of course that you let the voltage drops to 0V upon discharge. I read somewhere that NA-Ion allows you to go that low without degrading permanently the internal resistance or chemistry of the cell.

[rocketmanprojects]

That wide voltage range would make it pretty hard to use without a switch mode power supply. They are also more expensive than LiFePO4 batteries, which can be used as a replacement for lead acid batteries in many applications.