Sodium Cell Charging and Discharging Analysis, Hardware Compatibility. Future or Niche product?
Summary
TLDRThe video explores sodium ion batteries, testing their charge/discharge curves, voltage ranges, capacity, and compatibility with existing lithium hardware. It finds sodium batteries have very different charge behavior, with more linear discharge but lower usable capacity. Charging to 3.95V yields 1.3Ah capacity. Discharge plateau occurs around 2.6V, optimal cutoff is 2V. Inverter voltage ranges may only allow 80% sodium battery use. More testing is needed, but hardware changes seem necessary for full sodium support, challenging their drop-in claims.
Takeaways
- 😀 The video tests and compares sodium ion and lithium ion phosphate batteries
- 🔋 Sodium batteries have very different charge/discharge curves from lithium batteries
- ⚡ Sodium batteries can be charged from -10°C to 45°C unlike lithium batteries
- 🔋 The sodium battery voltage range is huge - from 1.5V to 3.95V per cell
- ⏱ A 1.3Ah sodium cell takes about 1.5 hours to charge/discharge at 0.5C
- 😕 Existing inverters can only use a portion of sodium battery capacity due to voltage limits
- 🤔 Not clear what the optimal sodium battery charge/discharge depths are for longevity
- 🛠 BMS parameters can be configured for sodium batteries, but hardware changes may be needed
- 🔬 More sodium battery testing needed - capacity, longevity, safety, overcharge tolerance
- ⏳ Overall sodium battery tech seems early stage and far from replacing lithium batteries
Q & A
What type of batteries are being tested in the video?
-The batteries being tested are sodium-ion batteries, which use sodium instead of lithium as the charge carrying ion.
How do the dimensions and appearance of the sodium-ion 18650 cells compare to normal lithium-ion cells?
-The sodium-ion 18650 cells have the exact same dimensions and look identical on the outside to standard lithium-ion 18650 cells. The only difference is they have a blue heat shrink wrap to denote the negative terminal.
What is the charging voltage and charging protocol used for the sodium cells?
-The sodium cells are charged to 3.95 volts at a rate of 0.5C with a cutoff current of 0.05C.
What are the key differences between the discharge curves of sodium-ion and lithium-ion phosphate cells?
-The sodium cell discharge curve is much more linear overall. It has a plateau region from 2.9-3V but lacks the steep voltage drop-off at the end that lithium-ion phosphate cells have.
Can existing lithium-ion phosphate BMS systems be reconfigured for use with sodium-ion batteries?
-Yes, the JK BMS tested in the video was configurable for the different voltage and current parameters needed for sodium-ion batteries.
What inverter challenges exist when trying to use sodium-ion batteries?
-Many inverters have tighter voltage cut-off thresholds that would prevent the full charge/discharge capacity of sodium cells from being utilized.
What is the typical shipping voltage for sodium cell prototypes?
-The manufacturer specifications indicate the cells are typically shipped with a 20-30% state of charge, not at 0 volts.
What further testing does the presenter want to conduct on the sodium cells?
-Additional tests proposed are overcharging to see if the cells will explode/catch fire since they are supposedly safe, and discharging fully to 0V to see if additional capacity can be obtained.
What open questions remain about best practices for sodium-ion battery usage?
-Optimal depth of discharge, impact of extreme charge/discharge on cycle life, and other usage recommendations are still yet to be determined.
Does the presenter think sodium-ion batteries will replace lithium-ion batteries anytime soon?
-No, he believes lithium-ion phosphate chemistry is currently very good and sees challenges around hardware compatibility with sodium-ion batteries being adopted.
Outlines
📽️ Introducing sodium batteries and testing plans
The video introduces sodium ion batteries that will be tested and compared to lithium iron phosphate batteries. Testing will look at charging, discharging, capacity, charge/discharge curves, suitable equipment like inverters and BMS, and safety. A 12V 50Ah sodium ion battery will also be tested.
📃 Specifications for the sodium ion cells
The key specifications for the 18650 sodium ion cells are provided, including capacity, voltages, charge/discharge rates, temperature ranges, cycle life, safety tests, and more. There is some confusion on whether the capacity is 1.3Ah or 1.5Ah.
💻 Software setup and initial charge test
The EB tester software and hardware are set up to test the sodium ion cell. An initial charge test is performed to 3.95V with 0.1A cutoff to analyze the charge curve and capacity.
🔋 Discharge test and analysis of curve
The cell is discharged at 0.5C down to 1.5V to get the full discharge curve. Capacity measures 1.3Ah. The curve shape is analyzed, showing a plateau region around 2.7V. 2V seems a reasonable discharge cutoff.
⚡️ Charge test and discussion of usage
The cell is charged back up at 0.5C, measuring 1.31Ah capacity. The charge curve is fairly linear. There are no usage guidelines on state of charge limits, unlike lithium batteries.
🔧 Testing compatibility with BMS and inverter
A JK BMS can be programmed for sodium ion batteries. Testing shows multiplus inverters can only use 86% of a 16S sodium pack due to voltage limits. So hardware changes may be needed to support sodium batteries.
😕 Challenges integrating sodium batteries
Even though BMS programming seems possible, inverter voltage ranges severely limit capacity usage of sodium batteries. Significant hardware changes may be needed for adoption. Lithium iron phosphate systems have no such issues currently.
🤔 Future sodium battery testing ideas
Further sodium battery testing ideas are proposed, like discharge to 0V, overcharge testing, and more capacity measurements. The differences to lithium batteries are highlighted.
Mindmap
Keywords
💡sodium batteries
💡charge/discharge curves
💡cut-off voltage
💡C-rate
💡state of charge
💡battery management system (BMS)
💡battery inverter
💡constant current charging
💡depth of discharge
💡safety testing
Highlights
Testing lithium and sodium batteries to explore questions about sodium batteries
Sodium battery dimensions and look identical to normal 18650 lithium cells
Sodium battery charge voltage is 3.95V, discharge cutoff is 1.5V - very different from lithium batteries
Can charge sodium batteries from -10°C to 45°C unlike lithium batteries
Discharge capacity at high and low temps is 85-98% of capacity at 25°C
Sodium batteries lose ~5% capacity per month when stored fully charged
Safety tests show no fire/explosion with sodium batteries after abuse tests
Discharge curve is very linear initially, then plateaus from 2.7-2.6V before dropping off
2V seems a good minimum discharge voltage based on the curve
Charge curve also quite linear, with rapid initial voltage increase
Can likely use existing BMS by programming limits for sodium chemistry
Inverters have very limited input voltage range - may only use 50-80% of sodium battery capacity
May need new inverter and BMS hardware designed for sodium chemistry
Lithium iron phosphate chemistry already mature, questions if sodium batteries will achieve breakthrough
More sodium battery testing videos coming on the channel
Transcripts
[Music]
[Music]
[Music]
guys welcome back to the offut garage
here in super super sunny and very very
hot Australia we have like uh 80 amps
outside at the moment and know I'm
already on 66% and it is 11:00 in the
morning I've got all the time to fully
charge this battery slowly today very
slowly because there will be Sunshine
until 5:30 or
so well guys what can I say you have
seen it in the intro we are going to
test
lithium we are going to test sodium
batteries na+ or salt batteries I tell
you there are a ton of questions about
sodium batteries out there and I'm going
to explore them all we will measure the
heck out of these sodium batteries doing
all the charge discharge test find out
how to charge how not to charge them we
will do capacity tests in both
directions have a comprehensive and
detailed look at the charge and
discharge curve of these batteries how
do they absorb do they need float mode
what equipment can be used with sodium
batteries the same inverter the same BMS
do we still need active balancers so we
will do the whole comparison between
sodium batteries and lithium iron
phosphate batteries we know lithium iron
phosphate batteries very very well we
have done a ton of testing here on the
channel discovered every angle of these
batteries but now slowly these sodium
batteries are sneaking into the market
and we want to see how far they actually
are can we replace lithium iron
phosphate with sodium batteries already
so these are just the questions I came
up while talking to the camera now I'm
sure you've got a million other
questions as well so without further
Ado let's get
[Music]
started so there you go sodium batteries
no lithium anymore huh so I bought these
four 18650 cells well this one is not
one of them this is actually a lithium
ion 18650
but if I mix them up you can't tell so
of course exactly the same d dimensions
and look as a normal 18650 cell and
these ones have a capacity of 1.5 amp
hours and a nominal voltage of 3.1 volts
and they come with the usual blue heat
rink negative on one side and the usual
positive terminal on the other side so
nothing special you cannot tell from the
outside that these are sodium batteries
and I bought four of them because I
wanted to build a 12vt battery but is
this actually possible with four of them
or do we need only three or do we need 5
um we don't know yet well to start with
let's have a look at the data sheet they
provided with these cells it's very
interesting so here's the document they
provided for these cells specification
for sodium iron rechargeable cell I
don't know exactly what kind of brand
that is I couldn't find the name of the
manufacturer of these cells here and
there was also a bit of confusion from
the beginning because these cells were
offered as 1.3 a hour batteries and it
says 1, 300 here in the specification as
well but here on the heat ring it says
1,500 so I guess we will find out so we
want to have a look at the definitions
before we start going deeper into the
specifications here so we've got a
capacity of 1.3 or 1.5 amp hours at 25°
we've got an end voltage of 1.5 volts we
can charge these batteries to 3.95 volts
with a constant current of5 C and then
we have the usual drop off of
0.05c at 3.95 discharging with a
constant current of
0.5c down to 1.5 volts so 1.5 volts is
our low limit and 3.95 is our high limit
so this is very different to our
well-known lithium ion phosphate
batteries so here are the
dimensions nominal voltage 3.1 volts
charge voltage up to 3.95 volt
discharge cut off is 1.5 internal
resistance is smaller than 20 milliohms
they claim an energy density of 118 wat
hours per kilogram and here's another
main difference to lithium iron
phosphate batteries we can charge these
batteries down to -10° C yeah only with
2 C but we can still charge these
batteries this would be a nogo for
lithium and from 0 to 45° we can charge
these cells with to 1 C if the battery
getss hotter than 45° we cannot charge
it anymore lithium phosphate goes to 55°
we can discharge these batteries down to
-30° C 0.2c again from 0 to
45° 3 C and I'm sure we will test this
in one of the upcoming videos and even
above 45° up to 60° we can still pull 05
C from this battery cell so as we have
seen already the maximum constant charge
current is 1 C up to 3.95 volts and then
at 0.05 C we consider the battery to be
fully charged we can discharge the cell
with up to 3 C down to 1.5 volts very
interesting okay charge and discharge
curves of sodium cells we're not looking
at that we will make our own charge and
discharge Curves in this video here so
here we have the usage conditions again
so we can charge this battery from -10
to + 45° and we can discharge from 30
to+ 60° C so that's a bit of a
difference to lithium ion phosphate so
here we have the test conditions
explained at 25° we are constant current
constant voltage charging this battery
to 3.95 volts with
0.5c and with a cut off of 0.05 c as
seen before the discharge constant
current down to 1.5 volts we're
discharging with 1 C 2C and 3C and
getting different results with the Capac
capacity so even at 3C they're claiming
we are still getting 98% of the capacity
but I'm not 100% sure how they mean this
here is this like a discharge capacity
at 1 C divided by discharge capacity at
0.5c and this gives you more than 99% of
the
capacity I don't know ah yeah I think so
so the cycle life is at 25° again the
same conditions to charge the battery
and discharging with 0 5c down to 1.5
and then we have a discharge capacity at
3,000 Cycles divided by a nominal
capacity gives us more than 80% I guess
this is how it works and here again the
capacity calculation for high and low
temperature this is always in relation
to 25° so discharging the battery at
very low temperatures gives you 85% of
the capacity discharging the battery at
very high temperatures gives you 98% %
of the
capacity then charging the battery at
25° to 3.95 volts with
0.05c cut off and storing the battery
for one month in these conditions and
then do a discharge test it gives you
95% of the capacity so it looks like
they are losing around 5% of their
capacity if you store them for one month
and then they have done all the safety
tests with them viberation test no
explosion no fire thermal abuse no
explosion no fire so they heated up the
battery to 130° C short current was also
no explosion no fire they overcharged
the battery with 1 C for 1 hour no
explosion no fire and they discharged
the battery with one C for 1.5 hours
there was also no explosion and no fire
they also did an impact test and there
was no explosion and no fire and then
there come the usual warning so don't
use these batteries in water don't put
them in fire so I will link this
document on our website as well as the
test results we are doing today so if
you want to have a closer look at at all
these specifications for these cells
here so I'm pretty confident we can
finish all the tests today charging and
discharging with taking the curves and
analyzing everything because I'm going
to discharge and charge this battery
with 0.5 C usually we use only 2 of a c
but then charging and discharging would
take 5 hours so here for a first look
and taking the curves 5c it will be so
for this test I'm using one of the
standard 18650 holders here it's a four
four battery holder but we using only
one slot here for one
battery and then I have already set up
the EBC a20 tester which we will use
connected to our computer to take the
curve and we will connect the positive
directly to this terminal and the
negative directly to this one over here
so we should have a voltage reading
already 3 5 six I just got a bit scary
at the moment because I thought this
battery is so full but now it's a sodium
battery it's not lithium ion phosphate
so 3.5 volts totally fine all right then
we are starting the EB tester software
ah I tell you what it feels so good we
want to actually connect this this com 7
yes it is okay so we've got now the
voltage here of our battery cell on the
Monitor and we want to constant voltage
charging with
um yeah well is this a 1.5 it doesn't
matter
0.75 amps to
3.95 volts and the cutoff current good
old calculator 1 5 0 *
0.05 cut of current is 75 milliamps
0.075 is that correct so just checking
again charging to 3.95 volts with 75
amps and and then we have a cut off at
75 milliamps all right let's uh fully
charge this battery and then we do the
full discharge with
05c I'm not sure how long this will take
here should be ready in about 20 minutes
or so all right see you then I guess I
will say this a lot of times in this
video
oh okay I think the cut off current is
.1 amps this is the minimum I can go
okay we go with that we're charging
we've got current and we've got voltage
which is rising all right see you in a
couple of
minutes oh we just pass the magical 3.65
volt
Mark and we keep charging oh
God while this uh battery is charging
here I have also a brand new 12vt 50 a
hour sodium ion battery here so this is
like a drop in 12vt battery and her
Miller from Miller energy in Sydney here
was so kind to donate this battery to me
um he bought actually a couple of them
to test them out they are prototypes and
he said he's not very happy with them so
he donated one to the offcut garage here
for me to test and the good thing with
this battery is we can also open the lid
here and have a look inside what kind of
BMS they have used what kind of cells
how the battery is being built so we
will do all this in a later video as
well having a look at this um 12vt 50
amp hour battery Tre uh just having a
quick look at these specifications here
so we've got a charge voltage here of
9.2 to 15.6 volts that is insane
standard charging 10 amps standard
discharging 10 amps maximum is 50 for
both so this will be very interesting to
test out the voltages are so different
wow
caution only use 15.6 volt charger to
avoid the risk of fire or explosion can
sodium batteries actually catch fire or
explode I thought they are so
safe all right we are charging now for
20 minutes or so we have reached the
3.95 volts the the current is tapering
off and we already down to 2
amps there are so tiny currents
unbelievable so I guess the cell is now
absorbing and before we start our
discharge test I also want to take the
temperature of this cell 33.5 de this is
at full charge now I'm not expecting the
battery gets too warm during discharging
but who knows so here in the cycle test
tab I have already programmed the
sequence so we're going to fully charge
the battery again to 3.95 volts and this
is only to get a common start point for
our discharge I will do this with all
the other cells as well and once we have
reach that we do the discharge and this
measures then the capacity and also
takes the discharge curve cve all right
charging has now stopped voltage is
dropping just a little
bit okay we start this test so it's
charging again to 3.9 5 volts 0.1 amp
cut off all right discharge has now
commenced yep discharging with
0.5c we've got the current up here
constant current and this is our voltage
curve all right I would say see you in
uh 2 hours 2 hours and then we have a
look at this discharge curve of a sodium
battery I'm very excited I'm literally
very excited this will be so different
okay we are now discharging for 15
minutes with um 75 amps voltage has gone
down from 3.95 to
3.5 and we can see a pretty linear
discharge curve so far it is very
lightly curved but very very different
to lithium ion phosphate okay I just
wanted to share this during the test
because I think this is a very
interesting well you find this
interesting as well otherwise you
wouldn't watch
this all right see you in a bit all
right and we are back in the garage
after 1 hour and 46 minutes and 20
seconds we've got the result we
discharged the cell from 3.95 volts down
to 1.5 with 7 50 milliamp of discharge
current and we got a capacity of 1.3 to9
amp hour so I'm not sure if these are
1.5 a hour batteries or 1.3 a hour
batteries still undecided here it could
be the large discharge current as well I
have a quick look at the
temperature this is 35° so 2° more than
before we started that's fine that could
be the ambient temperature here as
well so I will repeat this test with 2C
discharge and see if there's any gain in
capacity but I think these are 1.3 amp
hour batteries and not 1.5 as it says on
the heat shrink so here I can present
you the discharge curve of the sodium
battery and it looks very very different
to lithium iron phosphate very different
so this is where we started 3.95 volts
discharging and the curve is going down
very linear from here I would say to
this point here this is a very linear
discharge almost flat it's a bit banded
here at the top roughly until here but
then it goes very very linear down until
here at 2.7 volts obviously there
something happening with the Sodium
battery we have discharged
851 amp hour so far so that is 64% of
the capacity already used and then the
curve suddenly plateaus out a bit yeah
probably roughly until here 2.62 volts
and this where we have discharged around
1 amp hour so around 75% of the capacity
so and from here it goes downhill but we
still have 25% of the capacity there so
the voltage is going down further and
further we are at 2 volts
here here so here's exactly 2 volts and
we have discharged 1.25 1 amp hours
which is just over 95 4% of the measured
capacity then the voltage goes further
down there's another bit of a kink here
in the curve at around 1.7 volts but
then we have already discharged 1.31 amp
hours so we are close to 99% discharged
energy now so I would
say if you discharge them down to 2
volts and leave 5% in the battery that
would be fine this is probably like 3
volts with lithium ion phosphate
batteries then you've got like five six
or 7% still in the battery and usually
we stop discharging at 3 volts and I
would say the same here 2 volts should
be your lowest discharge of these
batteries so there is a bit of a jump in
voltage at the beginning when you fully
charge this battery to 3.95 volts but
then again do you charge to 3.95 volts
all the time you know this is like 3.65
with our lithium iron phosphate we
usually don't go that far do you leave a
buffer of 5% at the top and five at the
bottom and honestly I'm not even sure if
this is necessary with sodium batteries
so we are really missing out on these
important and significant points on this
discharge curve here like with lithium
ion phosphate where we have this steep
incline of voltage at the end and a
steep incline at the beginning and then
it plateaus out in the middle but here
it's a very
linear discharge curve bit of plateauing
then here and then it goes further down
and we know if sodium batteries are
getting getting stressed as well as the
lithium batteries so you keep actually a
buffer at the top and at the bottom well
we just don't know I guess we will do
some more testing in the future with
this battery here and see how far we
actually should charge maybe it's enough
if we charge to 3.7 volts and then
absorb here and it gives us almost full
capacity anyway watch this space well
here at the bottom I would say 2 volts
is a good number 95% of the capacity
should be fine to stop discharging
technically
we can actually discharge this battery
down to 0.0 volts right this is one of
the marketing Arguments for sodium
batteries you can discharge them to zero
volts and they don't take any harm but
from what I can see here I mean we are
down to 1.5 volts and the and the curve
goes really steep already I don't think
there's any capacity left between 1.5
and 0 volts so this is not the reason to
discharge them to zero volts the only
reason could be because of Transport the
this is what you can read everywhere you
discharge the batteries to zero volts to
transport them
safely well I have never heard of an
accident somewhere where they
transported lithium iron phosphate
batteries with about 30 to 40% state of
charge and they got into an accident and
because the cells were still charged to
30 or
40% it got really
bad I never heard of any incident
worldwide so
far if so I'm not sure if this
discharging to zero volt is not really
just a marketing trick hang on where was
this ah here here it says here in the
specification sheet as well single cells
are shipped with nominal capacity of 20
to 30% or according to customer
requirements so even here they're saying
the batteries will be shipped with 20 or
30% state of charge not with 0% state of
charge or zero volts okay I think this
is very very interesting to see this
discharge curve here and we now do the
reverse we are now charging this battery
up again to 3.95 volts take the full
charge curve talk about it analyze it
and see how far we should charge this
battery okay I have now programmed the
next task sequence here so we're going
to discharge this battery down to 1.5
volts again to get our zero point and
then from there on we take the curve and
charge it all the way up to 3.95 volts
with 75 amps and then when we hit 0.1
amps cut off weall it that's it that's
our capacity test for the charging and
we will have a look at the curve then of
course I have saved the discharge curve
and the data as well this will be all
available on my website I'll talk about
this again at the end of the video okay
there we
go we hit the task
sequence discharging
again okay and here we are charging
voltage is rising
steep obviously the charge current is
constant and voltage is rising very fast
we already at over two volts here after
a few seconds 2.1 volts Rising very
quickly all right I guess this is
another 1 hour and 40 minutes so we will
see us again
at at around 4:00 hey that's almost b:
right okay see you
then I'm back it is 4 30 1 hour and 44
minutes we have just reached the 3.95
volts you can see the voltage is now
being kept constant while the charge
current is going down very very quickly
we already down to 370 milliamps and at
100 milliamps that's fully charged then
so far we have charged
1,36 Mah hours into this battery so
pretty much the same as we have
discharged I really believe these are
1.3 amp per hour cells not 1.5 unless
the quality is so bad and they have just
less capacity as stated on the heat
shink we can take another temperature
measurement 35° stable at this uh
temperature so the tester has just
turned off voltage is now declining a
bit we have charged
1317 amp hours into this little cell
starting from 1.5 and finishing at 3.95
cut off 0.1 amps a fairly linear charge
curve so here's 1.5 volts and the next
measurement is already 2 volts so
voltage Rises very quickly at the
beginning I mean we have charged 1
milliamp hour into this battery and the
voltage has already jumped from 1.5 to 2
volts incredible and then we see a
fairly linear
increase a bit of a bow and then we've
got this Plateau here again in even in
the charge curve so roughly starting
from 2.9
volts and finishing probably here
somewhere at close to 3 volts the
incline is a bit flatter and then we see
a very very linear increase in voltage
and capacity right until we hit the 3.95
volts there's a bit of a Bend from maybe
from here all the way up but this is so
small so looking at the discharge curve
and now the charge curve here that means
you can actually measure the voltage of
this sodium battery and can determine
the state of charge of it just by
measuring the voltage so if you measure
3.44 volts this is roughly 50% of state
of
charge so and now let's determine so
we've got
1,317 at 1,2
51 so does it make sense to charge these
batteries to 95% only is this good for
the health well we don't know we've got
no information about this right and the
same with the discharge does it make
sense to stop discharging at 2 volts or
should we go all the way down to 1.5
will the sodium battery last longer if
we use it between 10 and 90% state of
charge we don't know so far there's no
recommendation there's no data there's
nothing out there
nothing so obviously they achieve the
3,000 Cycles by discharging the battery
from 3.95 volts down to 1.5
volts and here under cell usage
condition there's only the temperature
stated but there's no recommendation
about state of charge while lithium iron
phosphate manufacturers they actually
stayed use the battery between 10 and
90% but here I cannot read anything here
we've got our charge and discharge curve
again so it looks very similar to what
we achieved just looking through all the
specifications here again and there's
nothing in here so that is pretty
interesting before we have a quick
discussion about this I will save all
these information the curve and the data
for it as a CSV file on my website the
link is down under the video you can
download the EB tester software for free
you can import these CSV files I have
here created and have the exact curve
for voltage and current on your computer
you can then use the right Mouse click
to get all the data see it tells you it
tells you the voltage the current the
Amper hours and the wat hours for this
specific moment and you can drag your
mouse along the curve all the
information is there free of charge it's
free
um
actually uh let me go
into this BMS the JK BMS here this is
one of the new PB inverter
bms's and we put in the password and
let's see if I would be able to program
this BMS here for sodium batteries so
the cell over voltage protection at 3.95
volts set okay okay it has it has it has
accepted it we can set the requested
charge voltage to 3.9 Volts for example
yeah it would do it we would also reset
the um BMS to 100% at 3.9 n needs to be
lower come on JK 8 9 9 1 molt lower yep
and the cell over voltage protection
recovery I want to have at 3.8 volts
okay this was this is actually possible
to program what about the
1.45
volts okay accepted the under voltage
protection is at at 1.5
Vol accepted we are at zero at
1.55
Vols and the recovery would be at
1.75 Vol for example okay so obviously
we can use the JK BMS with sodium
batteries all the parameters can be
programmed for this type of chemistry
that's cool so what about your inverter
let's have a look at the victron multi
plus 2 so we have to make a decision
here what kind of battery are we going
to build a 48 volt battery obviously a
48 volt system how many of these sodium
batteries do we need to put in series to
get 55 57 volts so 57 volts divided by
3.95 14 so you're building a 14s system
can we build a 15s system 15
3.95 Vol is 9.28 so this will be in the
specifications for charging right so if
we go in here somewhere it should tell
us yeah the maximum the multipl plusus 2
can charge is 64 volts and if you put 15
of these sodium batteries in series
we've got 59.2 5 volts so we could
actually go one cell more and do a 16s
3.95 which would be 63.2 volts this
would still be in the spefic ifications
for the multi plus 2 so we could charge
a 16s sodium battery to 63.2 volts with
a multi plus 2 okay now we have to look
at the other side if we have a 16s
battery 16 * 1.5 because this is how far
we can discharge that would be holy
that would be 24 volts so let's have a
look in the inverter for the charger to
still be operational is 37.2 volts so
here uh
37.2 ided by
16 is 2.3 volts this is the maximum or
this is the minimum I can discharge the
batteries to otherwise my inverter would
shut down due to a low voltage
disconnect so here's our discharge curve
again and we have calculated
2325 volts 2.3
25 um 2.32 five there a come on
there there so this would be
1,151 amp hours milliamp hours out of
1,329 which is which is um 86% state of
charge so we could use the multi plusus
2 to fully charge this battery to 3.95
volts and then discharge it down to 2.3
something volts which gives us
86% 86.6% % of the capacity of a sodium
battery but this is the absolute maximum
the inverter can do it goes almost to
the maximum of 64 volts and it goes down
to the absolute bare minimum of 37.2
volts so we cannot use more capacity of
these sodium batteries with this
inverter how about other
inverters so I just did the calculation
here if we have a 12vt system
considering of a 4S sodium battery this
could be a voltage between 6 volts at
the very low end to 15.8 volts an 8A
system for a 24v battery lowest voltage
is 12 volts for a 24 volt system really
maximum voltage here 31.6 volts and a 48
volt as we have seen could be 24 volt to
63.2 volts so the voltage Delta is huge
with these sodium
cells and here let me turn on this
screen recorder again and here I have
the instructions for the fch for the for
the peder inverter the voltage range
goes to 10.5 to 15 volts the 24 volt
version goes from 20 to 30 volt and we
have 12 to 31 so we can only use a
porion of the battery and the 48 volt
version of the peder inverter goes from
40 volt to 60 volts let's go quickly
back into our discharge
curve this is
so you would be able to use only 80% of
your sodium battery ah actually no I'm
I'm incorrect here because the manual
says because it says the maximum voltage
is 60 volts not 63 we have to go into
the charge
curve over
here so charging the battery to 60 volts
only would leave us with 12% at the top
which we cannot use with this inverter
and what was the what was the other
number I can't remember I put this all
on the screen here so you will be very
limited what you actually can use from
this battery with the Peter inverter for
example and you can have a look in the
manual of your inverter you are using
and put these information down in the
video description what is the minimum
and maximum input voltage for your
inverter and then we can have a look in
the curve and can figure out how much
capacity would your inverter be able to
use from a from a sodium battery a 16s
sodium battery and to be honest this is
only one aspect we are looking at now
the voltage range from minimum to
maximum and the existing equipment on
the market and I'm sure they cannot just
output a new software update for your
inverter and then it will be sodium
ready because the hardware in your
inverter needs to run stable as well at
1.5 volt per cell for a 12vt system the
inverter still needs to run at 6 volts
or a bit over 6 volts so as you can see
this is already where the problem with
the Sodium batteries start we have
literally no Hardware to support this
sort of chemistry the jkbm seems to be
fine we can also have a look at other
bms's see if we can program the step
loss BMS for example for such a battery
or the pace BMS but the inverter side
seems to be far more difficult to match
the sodium chemistry and because this
cell number one is now fully charged
here I want to take the opportunity to
do another discharge test here with 2C
and see if I get more capacity out of
this battery yeah guys I guess so far
this video from this afternoon fully
charging fully discharging this sodium
battery very very interesting and very
different charge and discharge curves
right and with all the hype about sodium
batteries I'm not sure if these
batteries will always have a
breakthrough like the lithium iron
phosphate batteries and we see these
batteries here in cars in vehicles and
tools and or in ebike batteries and all
kind of stuff I mean this is one of the
first generations of um sodium batteries
here and they may put other goop inside
at some stage to have have a flatter
voltage curve then but imagine they have
to make new hardware like new inverters
and new um new bms's and new balancers
just because everyone wants some sodium
batteries now I think the lithium iron
phosphate battery chemistry is very very
good at the moment Top Notch Works a
treat and there are no issues with it
there are no safety issues there are no
hardware issues there are no battery
issues yeah all right guys I think we
are doing more testing with the Sodium
batteries if you want to see specific
tests please leave them down in the
comment section of this video here as
well I'll have a look and pick some of
them unfortunately the EC a20 tester
goes only down to 1 volts so we cannot
really discharge this battery to zero
volts here and measure their overall
capacity and see if there's any gain
from 1.5 to 0 volts that would be a test
I would be interested in and we don't
have any information how long we can
keep this battery on zero volts is that
good or bad for the battery why do we
stop at 1.5 volt then what is the
recommended depth of discharge for this
battery 90% 80% less 95 who knows well
and you have seen on the 12vt battery it
also States we can charge the battery to
15.6 volts while 15.8 volt would be the
maximum so I assume this is a 4S battery
inside as well and when we discharge it
it goes down to 6 Volts for 12vt battery
that is insane so we will do a lot more
testing with these batteries here in the
next couple of videos analyze the sodium
batteries in terms of charging and
discharging and um because these um
sodium cells are supposedly so safe now
what happens if we overcharge them if we
charge them to 5 volts or something what
happens are they exploding are they
start burning are they just gasing who
knows I guess we have to try that
somehow no please don't leave any of
these comments under the video here I'm
not able to do any short circuit test
here or overcharging test to five or six
volts or something until the battery
goes in Goes Up in Flames or explodes or
whatever I have I don't have the
equipment for here and it's far too
dangerous to do at home and I certainly
don't want to be in the news with these
new batteries but we will see we will do
some more testing and we'll see how much
capacity we actually get out of these
batteries so stay tuned for that as
always guys thank you so much for
watching thanks for all your amazing
support here on the channel and until
the next video guys you stay charged
stay safe and thanks again for watching
see you then
bye-bye ah before I forget I will um I
will of course link these batteries down
in the video description as well I think
I paid about 27 Australian dollars for
four of them well I'll link them down
below they also have bigger Prismatic
cells 230 whatever it says here on the
screen they have already offered me but
I don't really see the point to buy
bigger capacity cells because we are not
going to use them in a production
environment as of yet maybe in a couple
of years but who knows maybe they are
not coming to Market at all maybe they
are more suitable for very cold climates
where you have to charge your battery
and negative temperatures but we have to
wait and see it is all speculation right
now so let me know what you think about
these batteries I'm Keen to read your
comments I'm sure there will be lots all
right guys thanks again see you in the
next
video
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