What do we need to see on a cell specifications sheet? Of course we need high level data, but I think we need quite a bit more. This is my starter, but I would like to develop this list into a more concise draft for a datasheet.
Some of the better datasheets are from Saft [1].
Main data around physical, electrical, operating conditions and then some discharge curves on a second page.
I feel that 2 pages of data is probably about right for an initial overview of the cell.
However, this Saft datasheet doesn’t have the internal resistance of the cell, as in the DC internal resistance. This is a fundamental high level parameter that is used at the beginning of the cell selection process.
Key features
- Wh/kg
- Wh/litre
- W/kg
- W/litre
Designed to meet
- Safety:
- Transport:
- Quality:
Overview
| Nominal Capacity | Ah | defined cell condition, temperature and discharge rate |
| Nominal Voltage | V | defined cell condition, temperature and discharge rate |
| Maximum charge and cutoff voltage | V | define temperature, rates and any other conditions |
| Maximum continuous discharge | A and W | Cell temperature and other limits defined (eg cutoff voltage) |
| Maximum pulse discharge | A and W | 10s (also 2s, 5s and 30s), cell temperature and other limits |
| Operating temperature range | °C | maximum and minimum, separately charge/discharge if different |
| Storage temperature range | °C | maximum and minimum, plus other limits such as voltage |
Dimensions
- L: mm
- W: mm
- H: mm
- Mass: kg
Dimensional drawing + tolerances
Test data
- Maximum discharge current
- Short circuit current
- ACIR
- DCIR
Cell voltage versus discharge rate and cell capacity versus temperature.
Safety data
Description of safety standards and whether these were independent tests.
Results recorded against EUCAR Hazard Level.
Note that metrics are often checked against other values on the specification sheet. If they don’t match up because you used a different set of dimensions for the cell then this will throw the complete dataset into dispute.
Note: we would really like your input on this so that we can suggest a standard cell specification sheet to manufacturers.
References
- Saft 1p INT 174565 isr FL product datasheet
UKBIC could potentially assist you with the dimensional drawing aspect – tolerancing is an issue we are finding hard to define as we are not sure there is an industry standard for tolerances on battery cells in various formats.