Sodium ion batteries

I’ve had this old thread about alternative battery chemistries marinating in the back of my mind a while now. I’ve been interested in sodium ion batteries for a couple years, and I recently discovered some 1500mAh cells from Hakadi.

EDIT: These things charge up to 4.1V. All the stuff below about adjusting the charging circuit to avoid overcharging was nonsense, turns out. My protected battery boards kept me from charging to the point where I very well could have fried my motherboard. If I want to get full use of these batteries, I’ll need to figure out how to get the motherboard safely accepting 32.8V.

I’m not sure what it would take to adjust the charging circuit to avoid overcharging the cells. I know I have all the pieces necessary to answer my own questions there, but I just haven’t had the time available yet to figure it all out. As it stands, this chemistry is quite safe to overcharge a bit, so that’s exactly what I’m doing now in order to examine the feasibility of using such cells without any modification to the Reform.

I’ve completed two charge-discharge cycles with the computer sitting idle. The first discharge cycle took 120 minutes and the second took 118 minutes. This is consistent with the findings in this paper; specifically that a 20% overcharge results in roughly a 2% reduction in capacity. I’m curious to see if this degradation continues or not, so I’m going to use my computer normally and run tests every few days to see if any sort of plateau is reached. Once I get my current work on NixOS support to a stable place, I’ll have to see what I can do to modify my laptop to treat these cells correctly.

I posted about this experiment as I was running it and will try to continue posting in that thread as I learn more. I’ll add to this post here if I have any summaries to share, or if I figure out the appropriate charging circuit modifications.


isn’t the charge voltage for these ~4.1V ? so charging them to 3.6V would still be undercharging by a bit. (could be wrong but that’s how my brain understood it). I came across the hakadi batteries too and was thinking about using them. They also have a discharge cutoff of like 1.5V? compared to the lifepo4 batteries its a much bigger window. I think the charger works based on total series voltage which for sodium ion 4x8 would bring you up to 32V vs the ~28V for the standard batteries. The charge controller can handle that but idk how balancing comes into play and stuff like that and if the internal regulators are spec’d for over 30v? but yeah glad someone is poking around, i’ve been excited about sodium ion for a while.

You are correct. I didn’t even know how much I didn’t know what I was doing, apparently. I have the protected battery boards installed, so they got cut off at 3.5V when I charged up.