GM has been selling the Spark EV model through the Chevrolet brand for a few years now. It’s obviously a compliance car for the Californian market, offered in somewhat limited quantities, but it was also a stepping stone to the Chevy Bolt. With the launch of the Bolt fast approaching, it seems that it may be an interesting exercise here to take a closer look at how the battery packs of the Spark EV and the Bolt stack up against one another.
Push EVs stimulated the idea and did the legwork, so we’re sharing that excellent comparison a bit more widely, with a bit of my own thoughts.
The most obvious, and one of the most important, distinctions between the two models’ battery packs is the shape and installation location — the Chevy Bolt utilizes a so-called “skateboard” design, whereby the battery pack is located under the floor, whereas the Spark EV is clearly more of a jerry-rigged solution.
Push EVs notes, “the Chevrolet Bolt EV battery is made with 288 (3p96s) LG Chem cells, each cell is rated at 55 Ah and 3.75 V. I’m not sure about the 55 Ah capacity, but this is what I was told a year ago by a LG Chem worker. This represents a total of 59.4 kWh (288 x 55 Ah x 3.75 V). The battery volume is 285 L and the mass is 435 kg, this means an energy density of 208 Wh/L and 136 Wh/kg at the battery level, not cell. The Chevrolet Spark EV battery is made with 192 (2p96s) LG Chem cells, each cell is rated at 27 Ah and 3.75 V. This represents a total of 19.44 kWh (192 x 27 Ah x 3.75 V). The battery volume is 135 L and the mass is 215 kg, this means an energy density of 144 Wh/L and 90 Wh/kg at the battery level, not cell.”
The coverage then continues with speculation about why GM doesn’t release a new version of the Spark EV utilizing the 55 Ah cells, and choose to sell both models worldwide. While this is simply speculation on my part as well, I would guess simply that GM isn’t in that much of a hurry to actually sell large quantities of EVs. I suppose that we’ll know more on that matter in just a few months when the Bolt launches, though — it should be readily apparent whether GM actually wants to sell the Bolt or not.
Continuing, Push EVs writes: “Both batteries have liquid active thermal control that is very important to keep the battery at ideal temperature, since high temperatures damage the cells. We know that the Spark EV’s small 19.44 kWh battery can handle high charge and discharge rates, since it can provide 120 kW — 105 kW are intended to the motor — and can take up to 50 kW in CCS DC fast chargers. While Bolt’s 59.4 kWh battery can provide at least 150 kW to the electric motor and something more to the electronics.” That indicates that the Spark EV could (theoretically) see a decent upgrade, not that GM is really likely to provide one with this modified gasmobile.
It should be noted that it’s still an unknown how fast the Bolt battery will be able to recharge when using a CCS fast-charging station. GM has previously revealed that the model will be able to charge at 90 miles per half hour, but it’s not clear if these comments are unduly pessimistic simply as a means of avoiding complaints — due to the fact that most CCS chargers in the US are limited to 50 kW — and if the car could potentially charge much faster if it had access to a super-fast CCS charging station. It may be that the Bolt can be recharged quite fast, but that the infrastructure isn’t there so GM logically doesn’t advertise faster charging rates.
Any more thoughts on these batteries?