"Which cell?" is the question BESS developers, investors and even manufacturers ask us most.
Take 314 Ah, one of the most widely used cells in the BESS market today. Same capacity. Same format. A long list of suppliers. Very different prices. Very different cycle-life claims.
On paper, they all look alike. Over twenty years, they do not.
That gap is where engineering matters. So we built eMOBINO Energy Analytics, an in-house tool shaped by years of field experience. The full walk-through is below.
How the comparison is set up
Everything starts with evidence: datasheets, test reports and supplier links. The tool reads each file and extracts what matters.
Each cell gets its purchase price. In this demo the prices are relative cost units, not real currency. Characterising a cell properly takes weeks of lab testing, manufacturers do not always share the results, and buyers do not always know how to use them. We get the most out of the data that exists.
We shortlisted ten 314 Ah cells with published cycle-life claims from 4,000 to 18,000 cycles, including two unbranded ones. The project:
- Grid scale, 5 MWh, 2 hours, two cycles a day, cells retired at 70% health
- 30 °C, 90% depth of discharge, an electricity price of 60 cost units, 4% cost of capital
This is not a spreadsheet. It is a rapid digital twin of every cell: ageing models, electrical behaviour and years of field experience. To rank one cell against another, that is enough to expose the real differences. With project-specific data, it becomes a detailed engineering study.
What happened over twenty years
- An unbranded cell advertised at 10,000 cycles, under its own test conditions, collapsed just past year 4. Its health dropped sharply and its round-trip efficiency fell to 67%.
- The cheapest cell retired at 70% health in year 5. Over the project it was bought four times.
- The most expensive cell cost 45% more on day one, became cheaper over its lifetime just after year 5, and delivered every MWh 23% cheaper than the cheapest cell.
A datasheet alone does not show a collapse like this under your duty cycle. With unbranded cells, the usual suspect is manufacturing quality: uneven electrode coatings, poor electrolyte wetting, weak separators. These create local bottlenecks for current, which trigger lithium plating, electrolyte depletion and pore clogging. Ageing stops being gradual and the curve hits a knee.
Where each cell wins
The answer moves with the duty cycle. At two cycles a day, the most expensive cell wins at every project length. At one cycle a day, a different cell wins. At half a cycle a day, a standard cell wins for projects of up to thirteen years. The cheapest cell never wins, anywhere on the map.
What this means for your project
There is no best cell. Only the best fit for your project. The cheapest quote is not necessarily the cheapest battery.
Buy cheap, buy twice. Here, four times.
eMOBINO Energy Analytics is used inside our advisory work, only with each project's own data and the data its suppliers provide. If you are choosing cells for a storage project, contact us and we will start from your duty cycle.
