Sodium-ion self-discharge: only 6% lost over 539 days

When talking about battery storage, the focus is often solely on capacity, power, and price.
But there is one parameter that says a great deal about the real quality of a battery: the self-discharge.
And it's precisely here that our HEIWIT 10 kWh sodium-ion battery shows an extremely interesting figure.

What is self-loading?

Self-discharge is the natural loss of energy that a battery undergoes over time, even when not in use.
In other words: a battery can lose some of its charge simply by remaining idle.

For this reason, a low self-discharge value is a very important indicator.
This means that the battery can retain energy better over time,
reducing waste and maintaining the available charge for longer.

Why is this data so relevant?

A total loss of 6% over 539 days is equivalent to approximately 0.011% per day,
or around 4.11 TP3T (annual equivalent).
The battery maintains its energy extremely stably over time.

This is a tangible benefit, particularly in all those cases where the storage system is not stressed in the same way every day:
second homes, systems for occasional use, backup systems, homes with variable consumption or periods of low usage.

What does it mean for someone using a battery at home?

• More energy conserved over time, instead of being wasted unnecessarily.
• Greater real efficiency when the battery remains charged for days or weeks.
• More reliable performance even when the system is not used continuously.
• Less invisible energy waste, which in the long run make the difference.

The value of self-discharge in sodium-ion batteries

In the debate about storage technologies, the cost per kWh is often discussed, but much less about how much a battery lasts.
to actually store the stored energy.
And yet, this is precisely one of the aspects that separates a “datasheet” battery from one that's viable in real life.

The observed data on our HEIWIT 10 kWh battery shows a extremely low self-discharge.
It is the type of result that translates into a simple but fundamental perception:
The energy stays where it needs to stay, that is, inside the battery, ready when needed.

A small piece of data, a huge meaning

Losing just 6% over a period of 539 days is not just an interesting figure.
It's a concrete indicator of stability, Design quality e The capacity to store energy over time.

In a sector where every percentage point counts, being able to talk about approximately 0.351 TP3T per month: average self-discharge observed
means being able to show a real, measurable and immediately understandable technical feature.

Date calculated over the period between 31/10/2024 and 23/04/2026, amounting to 539 days.
The total observed loss of 6% corresponds to an average self-discharge rate of approximately 0.34–0.35% per month.