[newbie1984]

Hello I am new to this EV world just bought my first EV vehicle a 2014 Chevy Spark and I am looking to modify it. I love the car but the battery range is just not that great. Manufacturer says that it can have a range of 82 miles but being 2014 the most I can charge it is 67 miles. So I am hoping that I can replace the stock GM batteries with the Tesla 18650 batteries? And hopefully I can extent my range of the vehicle? Would anyone have any knowledge of working on the spark EV battery pack, and if this can be done? Any help would be great.

 

[brian_]

Why would you expect to increase range? Are you planning to put in a substantially larger pack, and if so... where would it go?

 

[newbie1984]

Why would you expect to increase range? Are you planning to put in a substantial larger pack, and if so... where would it go?

I have seen the GM Batteries on the spark EV , they are long and flat and I don't think they are as efficient as tesla battery technology. I will cram as much 18650 as I can.

 

[brian_]

I have seen the GM Batteries on the spark EV , they are long and flat and I don't think they are as efficient as tesla battery technology.

The Spark EV uses pouch cells, which are also long and flat, and don't have cases. As always with pouch cells, they are stacked into boxes to form modules, with almost no wasted space. The original (2014) Spark EV uses modules from A123. The later Spark EV uses the same cells as the Chevrolet Volt, because A123 went broke and GM started making their own batteries from cells made by LG Chem.

Tesla uses cylindrical cells, which are the same thing as a pouch cell but rolled up and stuffed in a can. The cylinders don't pack together well, leaving spaces between them - just look at beverage cans in a case. Tesla has no battery technology - the cells are designed and manufactured by Panasonic. Also, Tesla has moved on from the 18650 size (18 mm diameter by 65.0 mm long) to the 2170 size (21 mm diameter by 70 mm long).

While any battery company can build cylindrical cells, and several make lithium cells in the 18650 size, Tesla is the only EV manufacturer which uses cylindrical cells.

That's all about the shape and physical format. Electrode materials and chemistry are a different subject, and there's not much difference between brands, although the early Spark EV's cells are different from the later Spark Ev's. If you buy 18650 cells, unless they actually came from a Tesla they're not the same as the Panasonic cells which Tesla uses.

 

[brian_]

I will cram as much 18650 as I can.

The easiest way to put a lot of different cells in the original battery space of an early Spark EV would certainly be to find modules or prismatic cells from any production EV which happen to fit the Spark's battery case better. That won't be from the Chevrolet Volt (that's what GM did, but there's lots of empty space around them because they don't happen to be a size that conveniently packs in). If you had the measurements, maybe you would find something that would fit better.

There is an enormous amount of work in manually building a good pack out of many hundreds of tiny little cells. At about 13 watt-hours per cell, a 20 kWh pack (the capacity of the Spark EV's battery) would require about 1579 cells, in a configuration such as parallel groups of 16, and 96 of those groups in series. Do you realize that's about 3,000 welds onto battery ends?

The original Spark EV uses a cooling plate under the cells, which won't work for cylindrical cells. The later Spark (and Volt) use cooling plates between the cells. A Tesla uses ribbons of cooling tubes packed between the cells. Do you know how you would cool the 18650 cells? No cooling them is probably not an option, because with this shape and size of cell the ones in the middle of the pack will probably get too hot, and any temperature difference will likely cause imbalance problems.

 

[brian_]

If you need more information about what you're trying to replace (and improve on), this provides as much detail as I've seen:
A123 Chevy Spark modules

 

[newbie1984]

If you need more information about what you're trying to replace (and improve on), this provides as much detail as I've seen:
A123 Chevy Spark modules

Great thank you so much for the information that's is a lot to take in. I didn't think about the cooling of the batteries if I did swap to 18650, now I have to rethink how else I can extend my range.