LFP batteries are becoming more common in affordable electric vehicles, while versions with high range often remain loyal to the NMC technology. The Kia EV2, which offers both, constitutes a first case study to examine. Choosing between several batteries offered for the same electric car generally meant simply choosing between range, charging and performance reduced to price, with a simple assumption: the more expensive it is, the more powerful, the further it goes and the faster it recharges. But the rules change with the arrival of LFP batteries. These are increasingly preferred by manufacturers for the "small" models while the large ones retain NMC. This is true for the Kia EV2 that serves as our example today, but it is also the case for an entire new generation of models from the Volkswagen group, such as the ID.Polo, the Skoda Epiq or the Cupra Raval, as well as soon at Renault, R5, Mégane and Scenic. This makes the equation a bit more complex. The Kia EV2 offers two capacities, 42.2 and 61 kWh, but with two different chemistries. The small battery is of the LFP type (lithium-iron-phosphate), while the large one uses an NMC chemistry (nickel-manganese-cobalt). Examining their technical characteristics reveals some counterintuitive results: the small battery is associated with the most powerful motor and shows the highest voltage as well as a higher charging peak. Conversely, the large battery stores nearly 45% more energy for only a few kilograms more. With its 42.2 kWh, the LFP battery allows the EV2 to announce up to 317 km of range according to the WLTP configuration. With the 61 kWh NMC battery, the maximum range increases to 453 km. The gap thus reaches 136 km, or about 43% more range. For a car mainly intended for daily trips, the approximately 300 km of the small battery will certainly be sufficient for many drivers, especially with the possibility of home charging. To make the EV2 the main car of the household and multiply long trips, the 61 kWh become obviously much more interesting. Only 6 kg difference between the two batteries! This is probably the most surprising characteristic of the two packs: the 42.2 kWh LFP battery weighs 319 kg, against 325 kg for the 61 kWh NMC battery. In other words, only 6 kg separate the two, while the second carries 18.8 kWh, or nearly 45% more energy. This difference illustrates one of the main disadvantages of LFP: its energy density is generally lower than that of NMC chemistries. At comparable mass or space, the latter allows storing more energy. However, it is necessary to avoid drawing a direct comparison of the density of the cells from these figures. Kia communicates the mass of the complete packs, which include their structure, cooling system, electronics and protections. The architecture can be significantly different from one battery to another. But, for the driver, the finding remains remarkable: moving from 42.2 to 61 kWh hardly penalizes the mass of the EV2. For the manufacturer, there is another benefit to having a range of vehicles of roughly the same weight: not having to adapt the ground connections or braking according to the battery. The small LFP also has its advantages. This chemistry has several qualities, among which is good thermal stability. It is also known for its longevity: at comparable characteristics, these cells often support more complete charge and discharge cycles before experiencing significant degradation. They also better accommodate frequent full charges to 100%, which helps to partially eliminate the range gap. And it is even necessary and regularly requested by the on-board computer to perform a full charge to rebalance the cells. The small battery provides more power. The EV2 small battery is more powerful than the large one despite a motor that one might imagine identical. The first is associated with a maximum power of 107.8 kW (147 hp), against 99.5 kW (135 hp) with the NMC. The torque remains the same at 250 Nm. Result, according to the versions, the 0 to 100 km/h requires about 8.5 to 8.7 seconds with the small battery and 9.5 to 9.7 seconds with the large one. The chemistry intervenes because it influences notably the voltage of a cell, its internal resistance, its thermal behavior and the current it can accept in discharge. But there is no simple rule according to which "an LFP delivers more power than an NMC" - nor the reverse. Studies comparing cells show that power performance varies strongly with the chosen cell and its design, beyond just the chemistry. In the case of the EV2, it is particularly important because we observe something a bit paradoxical. A NMC cell normally has a nominal voltage higher than an LFP cell - typically around 3.6-3.7 V against 3.2-3.3 V. Yet, it is precisely the complete LFP pack of the EV2 that shows the highest voltage: 358 V against 297 V. This means very probably that the two packs do not have the same series/parallel architecture. Kia must use more LFP cells in series to achieve the 358 V, while the organization of the NMC battery favors more capacity in Ah. This is consistent with the values we have: LFP: 358 V × 118.2 Ah ≈ 42.3 kWh NMC: 297 V × 206 Ah ≈ 61.2 kWh. And that is where the voltage could indeed intervene in the 147 hp against 135 hp. Fast charging brings another result that seems, at first glance, paradoxical. Kia announces a 10 to 80% charge in 29 minutes with the small battery, against only 30 minutes with the large one. A one-minute difference while the latter stores nearly 45% more energy! The difference in chemistry can also contribute to explaining the different charging curves of the two batteries, the LFP and NMC cells not having the same electrical and thermal characteristics. But this does not explain everything: as with power, the exact type of cells, their organization in the pack, their cooling and the BMS strategy are also determinants. The small LFP reaches a slightly higher peak, 118 kW against 112 kW for the NMC. However, based on Kia's data, our calculations for a 10-80% charge give a theoretical average power of about 61 kW for the LFP against 85 kW for the NMC. The large battery must therefore maintain a high power much longer. What really counts is therefore the charging curve, and consequently the average power maintained throughout the session. We can estimate it quite easily from the official data. Going from 10 to 80% represents 70% of the battery's capacity. For the small LFP: 42.2 × 70% = 29.5 kWh These 29.5 kWh are theoretically recovered in 29 minutes, which corresponds to an average power of about 61 kW. With the large NMC: 61 × 70% = 42.7 kWh Recovering this energy in 30 minutes corresponds to an average power of about 85 kW. That completely changes the reading of the characteristics. The large battery shows a theoretical average power on the 10-80% about 40% higher than that of the small one. It recovers approximately 13 kWh more in just one minute more. At equal energy capacity, an LFP pack is generally cheaper to produce than an NMC pack. The main reason comes from the cathode materials. The LFP uses iron and phosphate, which are abundant and relatively inexpensive, and we find nickel, manganese and cobalt in the NMC cathodes, which are significantly more expensive and exposed to more price volatility. This is indeed one of the main reasons for the rise of LFP in entry-level and mid-range electric cars: one sacrifices part of the energy density to reduce the cost per kWh. This allows offering a cheaper battery when weight and space are not the main priorities. The Kia EV2 starts at €26,670 with the 42.2 kWh LFP battery in the Light trim which does not exist with the large battery. In the Air trim, the small battery costs €28,820, the large battery €33,320, which is €4,500 more. In the Earth trim, we go from €31,320 to €35,320. This time, the gap drops to €4,000. Finally, the GT-Line at €37,320 is only available with the 61 kWh battery. Therefore, with comparable equipment, it is mainly necessary to ask: does an additional 136 km of maximum range justify for you approximately €4,000 to €4,500? And there, the answer completely depends on your usage. There is ultimately no technology systematically superior to the other. For a car intended primarily for daily trips, the LFP battery has solid arguments: cheaper, durable and sufficiently autonomous for most uses. The NMC, however, retains a decisive advantage when it comes to carrying a lot of energy without exploding the weight and space, which makes it particularly relevant for long-range versions. The Kia EV2 mainly shows that it is not necessary to reduce this choice to the chemistry alone. Pack architecture, voltage, cells used, thermal management or charging strategy can produce results sometimes counterintuitive. Here, the small LFP is more powerful and shows the best charging peak, while the large NMC recovers much more energy in almost the same time. When choosing, it is therefore better to look at the use you will make of the car - and the entire technical sheet - rather than the three letters written after "battery".