Anyone messing around with Sodium batteries?

[cybermaus]

I have fallen a bit into the Sodium hype. Them being much more environmentally friendly, with only slightly less energy density than lithium.
And more robust to boot, as in, better able to deal with low discharge abuse and better able to deal with below freezing temps.

So I bought some 18Ah cells to experiment.
So far they work as expected.


Meaning, their biggest challenge is the very wide voltage span: 2V to 4V from empty to full.
(well officially 1.5V to 4V, but there is no more real energy below 2V)

So on a 4 cell (12V nominal) you need equipment able to handle 8V~16V
And on a 8 cell (24V nominal) you need equipment able to handle 16V~32V
Most equipment does not handle those ranges. Often they have a cutoff at 11V (22V)


I modded an 24V inverter to not have a low-cutoff anymore, and that seems to work well.
(I bought a old 24V one. It was just old enough to have discrete OpAmps for the low volt detection so a fairly easy mod)

My plan (for my mini camper) is to get 8 cells 200AH (24V nominal), and pay attention to use only equipment that has the full 12V+24V dual voltage car+semi volt ranges.
And the modified inverter of course.


Just need to figure out how to best deal with the remaining non-dual voltage stuff.
A step down seems obvious, but it should have really low standby current.

[moffy]

FYI read: https://www.eevblog.com/forum/projects/sodium-ion-battery-evaluation/msg5156514/#msg5156514

[cosmicray]

To use this properly, you would need a voltage multiplier that operates on fractional multipliers. I've seen an academic paper or two on this subject, and typically having to do with energy harvesting.

[cybermaus]

Sorry, you lost me here?
I need a voltage multiplier for energy harvesting?

I have the impression you are responding to a different topic than what I was bringing forward.
If not, please explain a little better.