More details on the Samsung SDI 94 Ah battery cell
Great lifespan and average energy density on the battery cells used in BMW i3.
It’s not the first time that we found Samsung SDI 94 Ah battery cells on sale at online stores, but it’s the first time it happens at a reputable and well known source.
The price at ev-power.eu isn’t very friendly (162,69 € without VAT), but it’s always nice to at least have the opportunity to buy the battery cell from third-party suppliers if we really need to.
Below is the information we can find at the online store.
Li-Ion prismatic Samsung 94 Ah special cell for EV and energy storage applications provides long cycle life > 3.200 cycles by Nickel-cobalt-manganese (NCM) technology.
- Nominal voltage of the cell is 3,7 V and the operational voltage is 2,75 V – 4,15 V.
- Recommend charging/discharging current is 0,33 C (31 A)
- Cycle life: 3.200 cycles at 80 % DoD (Deep of Discharge) up to 80 % residual capacity (at discharge current 94 A)
- Maximum discharge current is 1 C continuously and peak 4,3 C (413 A, <5 s).
- Maximum charging current is 0,5 C continuously
- Dimensions: 173 x 125 x 45 mm
- Weight: 2 Kg
- Charging temperature: 0° C ~ 60° C
- Discharging temperature: -25° C ~ 60° C
With these numbers we can calculate – the always interesting – energy density figures.
Gravimetric Energy Density: 173,9 Wh/kg
Volumetric Energy Density: 357,4 Wh/L
The energy density figures aren’t great, which gives Samsung SDI a lot of room for improvement. The long cycle life is without doubt, the strong point in these battery cells.
If we look to the BMW i3 battery pack, just the 96 battery cells used in it weigh 192 kg (96 x 2 kg), have a volume of 93,42 L (96 x 0,973125 L) and a capacity of 33,39 kWh (96 x 3,7 V x 94 Ah). However, when we put the battery cells in modules and add electronics such as a TMS and BMS, the battery pack becomes larger and heavier.
What’s interesting is that the recommended maximum charging current is only 0,5 C and we know that the BMW i3’s 33,39 kWh battery can be charged by a DC fast charger at 49,5 kW, which is roughly 1,48 C.
To sum up, while Samsung SDI battery cells have only average energy density, they are very durable and reliable. This is one of the reasons why I think that the BMW i3 battery is great and also why I recommend to buy an used Fiat 500e.
I’m curious to see which kind of new battery cells will BMW use in the upcoming BMW i3S with the larger capacity battery pack. If the rumored battery pack is around 50 kWh, it’s very likely it’ll get the new cylindrical 21700 cells and not the prismatic type – that has been used until now.