Sodium Cell Charging and Discharging Analysis, Hardware Compatibility. Future or Niche product?

Summary

The 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.