Sodium ion batteries vs LiFePO4

[OffGridForGood]

There seems to be some relatively serious investment going into sodium batteries.
At this point, it looks more feasible for large energy storage projects, though the 5000 cycle is considerably less than Lithium provides so it seems like there would have to be a very substantial cost offset.
Time will tell.

Sodium in Batteries: Shift May Herald Another Shakeup

Battery giants are starting to put their money on new sodium-based technology, a sign that there could be yet another shakeup in the industry that’s crucial for the energy transition.

www.bloomberg.com

The net energy will be the scale to evaluate: if an energy storage system needs to use a portion of that stored energy for temperature regulation with Lithium, but does not need temperature regulation with Sodium - this will be a huge impact.

Imagine the energy use for A/C just to keep batteries cool in hot locations (like TX, AZ, NM, So-Cal), or likewise the energy to maintain at least 32F temps in colder climates (AK, Canada, Finland, etc) - a cell that needs no heating or cooling is a big win.

All that said, the Sodium cells have a much wider voltage curve and to use them with existing inverters, I expect we will not use the full voltage range. This will be a pos and neg thing" pos - the cells will last a long time being cycled through a smaller voltage range than their capacity; neg - the availabel usable capacity will be lower. I am excited to get some to try out.

 

[Xepshunall]

I really don't care what people have to say about the need for new charging methods. I intend to build a daily commuter car for my 10-mile round-trip for work. It'll have dual 48-volt banks that get connected in series when the car is powered up. I'll charge it from my home battery bank and each will have a 16-S (32s) BMS. Given the voltage range of the cells, I don't see why I'd need to be concerned. My home solar can't exceed the safe voltage and the cells are good down to 1.5 volts. I believe that people are over-thinking. I'll be staying well within the voltage range and be able to charge my car without pre-heating the battery packs. If there is a legitimate concern that I'm overlooking, I'm very receptive to constructive criticism. If it's that I'm wasting the potential of the cells, this is not my concern.

 

[OffGridForGood]

I really don't care what people have to say about the need for new charging methods. I intend to build a daily commuter car for my 10-mile round-trip for work. It'll have dual 48-volt banks that get connected in series when the car is powered up. I'll charge it from my home battery bank and each will have a 16-S BMS. Given the voltage range of the cells, I don't see why I'd need to be concerned. My home solar can't exceed the safe voltage and the cells are good down to 1.5 volts. I believe that people are over-thinking. I'll be staying well within the voltage range and be able to charge my car without pre-heating the battery packs. If there is a legitimate concern that I'm overlooking, I'm very receptive to constructive criticism. If it's that I'm wasting the potential of the cells, this is not my concern.

Do you have an inverter in mind that will work with the wide voltage range of the sodium cells? Curious.
ie 16s @ 1.5 volt = 24v, if you series two packs = 48v at the low end, but at the top end 4v x 16 = 64v and series connected x 2 =128 volt,
How will you utilize 48 to 128 volt range?

 

[Rednecktek]

That voltage curve sure looks a lot like lead acids. What's the comparison there look like?

 

[Xepshunall]

Do you have an inverter in mind that will work with the wide voltage range of the sodium cells? Curious.
ie 16s @ 1.5 volt = 24v, if you series two packs = 48v at the low end, but at the top end 4v x 16 = 64v and series connected x 2 =128 volt,
How will you utilize 48 to 128 volt range?

Each BMS will be 32s. I intend to use two of the same BMS that I would use for a 48-volt LiFePo4 battery. My home battery system is Lead-Acid and, when either or both of the 48-volt banks is switched to the charging position, it will disable the ignition switch and each car battery bank will charge directly from my home batteries and from the off-grid inverter. I see no reason for the need of any inversion. I have enough DC electrical knowledge to wire this up. My only concern is finding the appropriate contactor. There is little need for more than 96 volts in my city car but I'm aware that the upper end of the battery voltage will hit 117.2 volts when all of the batteries are connected because my home system is charged at 58.6 volts. This 3.6625 volts per cell is well within the safe range of the Sodium Ion cells. Still, I know that I'm only human so it is possible that I haven't considered all factors. As for DC to DC for 12vdc accessories, that should be simple enough. If anyone thinks to warn that the charging characteristics of Lead-Acid could cause damage to my new cells, I've thought about this and have purchased a device explained in this video.

 

[OffGridForGood]

Interesting,
what motor do you have in mind for this project?

 

[Xepshunall]

Interesting,
what motor do you have in mind for this project?

15kw High Rpm Induction Motor For Electric Kit - Buy High Rpm Ac Gear Motor,15kw Plug In Hybrid Car Conversion,20hp 15kw Electric Motor Product on Alibaba.com

15kw High Rpm Induction Motor For Electric Kit - Buy High Rpm Ac Gear Motor,15kw Plug In Hybrid Car Conversion,20hp 15kw Electric Motor Product on Alibaba.com

www.alibaba.com

I explained to the salesperson that I want to be able to reach and maintain 55 mph for as much as 7/10 of a mile 10 times per week without harming the drivetrain. This is the kit she suggested.

 

[OffGridForGood]

15kw High Rpm Induction Motor For Electric Kit - Buy High Rpm Ac Gear Motor,15kw Plug In Hybrid Car Conversion,20hp 15kw Electric Motor Product on Alibaba.com

15kw High Rpm Induction Motor For Electric Kit - Buy High Rpm Ac Gear Motor,15kw Plug In Hybrid Car Conversion,20hp 15kw Electric Motor Product on Alibaba.com

www.alibaba.com

I explained to the salesperson that I want to be able to reach and maintain 55 mph for as much as 7/10 of a mile 10 times per week without harming the drivetrain. This is the kit she suggested.

I hope you post your build and how it performs, interested to see the result.

 

[Xepshunall]

The automotive industry should be interested too. They make city cars too complicated and expensive for their purpose and if anything can reduce a carbon footprint, this can. The cost for the drivetrain is $2800 not counting shipping.

 

[OffGridForGood]

Long before Solar, I was/am a car buff.
Seeing these kits coming on line is very exciting. Part of the reason for my own interest in Sodium batteries - Canadian Winters. LOL.
I leaned from this forum and YouTube to build my own battery packs, and now have six 280/304's plus smaller 12 and 24 volt packs and more E-bike battery packs than I can count.
Building batteries was a stepping stone to learn what it might take to build a car battery from cells.

 

[Xepshunall]

I put the deposit down on a conversation kit with a 144 volt motor and controller. I chose this because it's still divisible by 48 and can hit 55 mph in a 4000 pound truck with it's 500 pound payload. The kit is rated 18 Kw with a peak of 42 Kw. The cost is just under $4800 shipped to my house. I'll have to use my existing batteries for the initial run and will swap them with Sodium as soon as I can afford to buy them and the 3 BMS that will allow me to series my 3 packs. I don't know that any will exist early on in the adoption phase.

 

[billvon]

Each BMS will be 32s. I intend to use two of the same BMS that I would use for a 48-volt LiFePo4 battery.

That BMS will limit you to a range of about 2 to 3.6 volts. Na-ion generally operate over a range of 1.5 to 4.3 volts. So you'll be losing a significant fraction of the cell's capacity by operating within the narrower voltage range.

But if you are OK with that, that can work.

 

[Xepshunall]

I neither intend on fully charge them nor deeply discharge them. I understand that this may have a dramatic effect on my usable range because I read that the SoC curve isn't much of a curve but practically linear.
If this is true, there may be no point in trying to use them for anything but a FLA replacement as a starter battery. I hope I'm mistaken.

 

[upnorthandpersonal]

Andy did some NaI charge/discharge tests and looks at possible cut-off voltages and capacity remaining:

 

[Pi Curio]

Curious, what if we would use 17 cells instead of 16, and discharge to 2.5 and charge up to 3.45V?. i e. 42.5V - 58.65V.

Would that help close the gap in terms of usable capacity?

 

[wattmatters]

They will have a similar functional/useable capacity as lead acid. Specialist applications (e.g. extreme cold) makes sense but unless they are a bucket load cheaper than LiFePO4 I can't see why one would bother.

 

[OffGridForGood]

They will have a similar functional/useable capacity as lead acid. Specialist applications (e.g. extreme cold) makes sense but unless they are a bucket load cheaper than LiFePO4 I can't see why one would bother.

I bought my Sodium packs to test in cold weather, however I think the real benefit is actually high temperature - places like Australia, TX, AZ, NM, So Cal, etc have temps high enough that LFP need a conditioned space, to avoid high temperature degrade. The Sodium cells appear to have much higher temperture tolerance, perhaps avoiding energy consumption for cooling ESS in these environments.

Charge and Discharge in temperatures up to 55C (131F)
Battery spec for my 12v pack attached for reference.

 

[OffGridForGood]

I am testing them with my 12 and 24 volt inverters, not too much capacity lost due to voltage limits of the inverter, but as the voltage increases, the Sodium's higer voltage cells get farther and farther from the LFP ranges. Not really suitable for 48v inverters yet, or change to 15s?
3.95v top voltage x 16 = 63.2v
2.5v bottom voltage x 16 = 40v
The inverters need to have wide voltage limits to be able to charge and discharge the full capacity of the Sodium cells, we should make a list of existing inverters that can utilize the full sodium voltage range and post it to this thread.

 

[codfish]

How about a hybrid/combined Sodium => LFP. Set up a large sodium battery, at a somewhat higher voltage and use this to continuously charge ( with a PV charge controller) a much smaller LFP battery to meet surge and have a more stable voltage. The PV charge controller already accepts a wide input voltage and can handle a standard LFP charge profile. Finding a charger for the higher voltage sodium might be a bit easier that redesigning inverters.

Of course this doesn’t help the cold climate battery problem.

 

[OffGridForGood]

How about a hybrid/combined Sodium => LFP. Set up a large sodium battery, at a somewhat higher voltage and use this to continuously charge ( with a PV charge controller) a much smaller LFP battery to meet surge and have a more stable voltage. The PV charge controller already accepts a wide input voltage and can handle a standard LFP charge profile. Finding a charger for the higher voltage sodium might be a bit easier that redesigning inverters.

Of course this doesn’t help the cold climate battery problem.

Could work and take care of the wider operating voltage range of the Sodium. Not sure what the MPP function would do with a battery as the supply DC to a PV input. {I should try it out!, use a 24v Sodium battery as the PV input DC on my 12v inverter, running on a 12v LFP pack}

Playing with the 12v and 24v inverter settings, the upper voltage limits are high enough to use the full Sodium voltages that my factory packs came with. The lower end is where a bit of capacity is lost, since my inverters will not accept down to the 1.5v per cell the Sodium supports (4x1.5 = 6volt is too low, but the capacity between 6 and 9 volts, the lowest setting for my 12v inverter is only 10% of the battery).
As the battery base voltage increases, 12v, 24v, 48v, the difference between LFP and Sodium increases.

Sodium batteries are the new kid on the block, and LFP are the well established tech. I would expect the Sodium to be far more expensive until the production volumes increase, but this was not the case. The Sodium batteries were a bit more expensive, but not x2. Future increases in production volume, wider availability of sodium sources should make these cells vastly lower cost to produce than LFP eventually.

LFP cells like temperatures that people like, above freezing point and below 35c/95F this is fine indoors, but not so outdoors in much of the world.
Sodium cells on the other hand run fine outdoors at minus 20c/-4F (I have tested this in the real world) and per the documentation up to temps I will never see 55c/131F which should be exciting news for the guys in hot places around the globe, cells that don't need A/C environmental controls would seem like a great option.