This is a good explanation as to why you wont be installing sodium batteries in your boat

[PaulRainbow]

Just to be a bit of a "Devils Advocate" I would think that most if not all of theses conditions would be applied to any battery or charging facility.

Not so sure Alex.

● The battery must not be stored in high temperature locations, in direct sunlight or left inside a vehicle in hot weather.
On a boat, in the Med ?

● The battery must only be charged using a Sodium-Ion charger.
Is there such a thing ?

● When charging, the battery must not be left unattended or when charging for long periods.
So no charging when away from the boat, or using them as UPS, or solar installations in your house ?

● When fully charged the battery charger must be disconnected from the terminals and the mains power supply.
How does this work ?

● The charging premises must have an appriopiate fire detection and alarm system and appropriate fire prevention
equipment.
I'll give you this one

● The battery charge state should be checked regularly and must be recharged to 80% at least every three months when
in storage.
Doesn't apply to LFP or AGM or LA if disconnected or isolated.

● The battery is not able to be transported on passenger flights.
I doubt this is true for LFP or LA, but likely also not rue for Sodium. Just that one supplier setting imaginary restrictions.

 

[Alex_Blackwood]

Not so sure Alex.

● The battery must not be stored in high temperature locations, in direct sunlight or left inside a vehicle in hot weather.
On a boat, in the Med ?

● The battery must only be charged using a Sodium-Ion charger.
Is there such a thing ?

● When charging, the battery must not be left unattended or when charging for long periods.
So no charging when away from the boat, or using them as UPS, or solar installations in your house ?

● When fully charged the battery charger must be disconnected from the terminals and the mains power supply.
How does this work ?

● The charging premises must have an appriopiate fire detection and alarm system and appropriate fire prevention
equipment.
I'll give you this one

● The battery charge state should be checked regularly and must be recharged to 80% at least every three months when
in storage.
Doesn't apply to LFP or AGM or LA if disconnected or isolated.

● The battery is not able to be transported on passenger flights.
I doubt this is true for LFP or LA, but likely also not rue for Sodium. Just that one supplier setting imaginary restrictions.

I take your point Paul. However if I was writing instructions for storage, use and charging, bearing in mind the H & S and litigation around the world. I would be covering my backside in armour plate. Obviously the things like disconnecting chargers from batteries and mains and not leaving unattended etc are somewhat debatable. But all contribute to "We did tell you". As I said I was being a bit Devils Advocate
If you followed all of these statements you certainly wouldn't buy one. I think your last statement sums it up

 

[Sea Change]

I'm sure something better than LifP04 will come along at some point, but not today.

What is it about LFP that you think isn't already good enough?

 

[Ceirwan]

What is it about LFP that you think isn't already good enough?

Nothing in particular, they're great batteries.
In the same way there's nothing in particular about my computer or phone that's not good enough, but at some point in the future better ones will exist.

Probably in the future we will get batteries that are more energy dense with less weight without any additional safety risk, that can maybe be charged lower temps etc. I'm simply saying this Sodium battery doesn't seem to offer any compelling use case to switch.

 

[Sea Change]

Nothing in particular, they're great batteries.
In the same way there's nothing in particular about my computer or phone that's not good enough, but at some point in the future better ones will exist.

Probably in the future we will get batteries that are more energy dense with less weight without any additional safety risk, that can maybe be charged lower temps etc. I'm simply saying this Sodium battery doesn't seem to offer any compelling use case to switch.

Lower cost and greater energy density would certainly be incremental improvements. But I would say that LFP has already reached a point where the density and cost make it a no brainer for domestic power for boats. Continued improvements would allow greater uptake of electric propulsion though.

The main barrier to LFP adoption now seems to be the changes needed to the rest of the system- and this largely stems from the ability of LFP to charge and discharge at very high rates, and to shut off abruptly when limits are exceeded. You can't really have the benefits of LFP without also having to deal with those features.

 

[Baggywrinkle]

Just as Lithium batteries come with a BMS to look after them, I'm sure it's possible to sweep up most of the mentioned issues with sodium batteries using some additional electronics.

This sounds to me like a VHS/Betamax moment .... Lithium is now an established technology, Sodium is a challenger but the tech isn't quite mature enough yet. It will all depend on how the market reacts and it may turn out that sodium ends up filling different niches to lithium and both end up co-existing.

... or something better might turn up which makes both obsolete.

I'm watching with interest, but my son is very keen on the prospect of sodium and may well end up using them as a home battery bank.

 

[geem]

...

Just as Lithium batteries come with a BMS to look after them, I'm sure it's possible to sweep up most of the mentioned issues with sodium batteries using some additional electronics.

This sounds to me like a VHS/Betamax moment .... Lithium is now an established technology, Sodium is a challenger but the tech isn't quite mature enough yet. It will all depend on how the market reacts and it may turn out that sodium ends up filling different niches to lithium and both end up co-existing.

... or something better might turn up which makes both obsolete.

I'm watching with interest, but my son is very keen on the prospect of sodium and may well end up using them as a home battery bank.

I think sodium is fundamentally different, at the moment.
Lifepo4 can mimic lead acid voltages such that a boat can be readily converted to run on it. Sodium has so much of its capacity below an acceptable threshold voltage limit for all our normal day to day electronics that a whole new bit of electrickery will be needed beyond what we need to run lithium.
Inverters will be one key item

 

[Trident]

The biggest producer of lithium is Australia- I don't think they have kids mining it there.

Maybe you're thinking of cobalt?

Cobalt is bad too but Lithium is mined in South America and Nigeria for example, by child labour

 

[Baggywrinkle]

...

I think sodium is fundamentally different, at the moment.
Lifepo4 can mimic lead acid voltages such that a boat can be readily converted to run on it. Sodium has so much of its capacity below an acceptable threshold voltage limit for all our normal day to day electronics that a whole new bit of electrickery will be needed beyond what we need to run lithium.
Inverters will be one key item

I understand your concern, but 12V battery powered devices have been designed to continue to function at voltages well below 12V for years .... a Victron 12V Inverter is good down to 9,7V ... and a Raymarine Axiom Plotter has an operating voltage of 8-12V ... the only issues I see may be LED lighting if it runs directly from battery voiltage. This has all come about due to the automotive industry where things have been running from small 12V batteries for decades. The internal power supplies for these components are also used in other industries, like boating.

Vehicle systems have been designed to withstand massive variations in supply voltage since the 90s when electronic control units became the norm in vehicles.

Introduction​

Powering automotive electronics systems can be challenging due to requirements of high reliability while contending with a relatively unstable battery voltage. The variety of electrical and mechanical systems that interface with a vehicle’s battery can cause wild voltage excursions in the nominal 12 V supply. In reality, 12 V can vary from –14 V to +35 V for extended periods of time and experience voltage spikes with extremes ranging from +150 V to –220 V. Some of these surges and transients arise from everyday use, others from fault conditions or human error. Regardless of cause, the damage they can produce in a vehicle’s electronics system can be difficult to diagnose and expensive to fix.

The experience of automakers over the last century has led to a catalog of electrical conditions and transients that are known to disrupt operation and cause damage. The International Organization for Standardization (ISO) has compiled this industry knowledge into the ISO 16750-2 and ISO 7637-2 specifications for road vehicles. At a minimum, the power supply for an automotive electronic control unit (ECU) should survive these conditions without damage. For critical systems, functionality and tolerances must be maintained. This requires that the power supply regulates the output voltage through the transient to preserve ECU operation. Ideally, a complete power solution avoids the need for fuses, minimizes power dissipation, and features low quiescent current to support always-on systems without draining the battery.

https://www.analog.com/en/resources...ctronics-systems-with-no-switching-noise.html

Obviously at 9,7V more current is required to achieve the same power, but if the battery can supply it then there is no issue.

 

[justanothersailboat]

The wide voltage range doesn't seem impossible to work with any more than the voltage range with solar. We already use all sorts of very high efficiency dc:dc conversion in things, sooner or later a battery controller for these cells will just include one and provide stable 12v to all the devices that need that. Which might be fewer than you think, given all the things that already do their own internal power conversion. (eg - out of curiosity I looked up what my plotter will accept and it turns out it's already happy with 8-16v...)

(edit... and others got there between my writing 80% of this and actually having the time to finish it, sorry)

 

[Sea Change]

The wide voltage range doesn't seem impossible to work with any more than the voltage range with solar. We already use all sorts of very high efficiency dc:dc conversion in things, sooner or later a battery controller for these cells will just include one and provide stable 12v to all the devices that need that. Which might be fewer than you think, given all the things that already do their own internal power conversion. (eg - out of curiosity I looked up what my plotter will accept and it turns out it's already happy with 8-16v...)

(edit... and others got there between my writing 80% of this and actually having the time to finish it, sorry)

Adding extra transformers is only going to make the already very poor round trip efficiency of sodium even worse.
Perhaps the technology has promise for large scale grid storage, if it is massively cheaper than lithium.
But for boats, the extra complexity of dealing with a wider voltage range, and the very poor charging behaviour, mean that lithium already beats it hands down.
If you don't care about round trip efficiency and charging rates, then just stick with lead acid.

 

[jakew009]

Simplistically, determine how many cells would be needed so that the battery never went below 13V, then add a DC-DC charger to give a constant, stable 12V. This could be built into the BMS.

The challenge will be doing that efficiently and cost effectively. A typical fet based BMS can handle 200/250A and all of that is required to run a 3000W inverter.
A 12V boost converter capable of handling 250A is going to be massive and very expensive.

I understand your concern, but 12V battery powered devices have been designed to continue to function at voltages well below 12V for years .... a Victron 12V Inverter is good down to 9,7V ... and a Raymarine Axiom Plotter has an operating voltage of 8-12V ... the only issues I see may be LED lighting if it runs directly from battery voiltage.

The problem with the low voltages is that after voltage drop is taken into account at high currents, the voltage is going to be ludicrously low approaching 6V or something. The cables would need to be twice as big as they are now!

It’s much more practical at higher voltages. Say 4 batteries in series - 32v fully discharged to 64V fully charged but that’s still one hell of a swing and requires new inverter designs.

A Victron multiplus 48V can handle 38 to 66V before voltage drop comes in to play.

 

[Ceirwan]

Lower cost and greater energy density would certainly be incremental improvements. But I would say that LFP has already reached a point where the density and cost make it a no brainer for domestic power for boats. Continued improvements would allow greater uptake of electric propulsion though.

The main barrier to LFP adoption now seems to be the changes needed to the rest of the system- and this largely stems from the ability of LFP to charge and discharge at very high rates, and to shut off abruptly when limits are exceeded. You can't really have the benefits of LFP without also having to deal with those features.

I think you read more into my original post than I intented.

I was simply meaning that LFP is the best we have right now, but I'm sure that one day we will get something better come along. I have an Lfp battery, it wasn't a comment against the technology!