Batteries have come a long way. In 1800, Alexander Volta invented the first true battery. The first rechargeable battery was invented in 1859.
Lithium batteries which have “revolutionized our lives” only came into the market around 1991.The first lead-based batteries were heavy and inefficient. Today’s lithium batteries were so light that smart phones and other appliances are powered so efficiently that you may not even know they are there.
Below are some interesting facts about batteries and Tesla Model 3’s battery pack.
Interesting Facts About Batteries And The Battery Pack Used In The Tesla Model 3
1. Lithium is the lightest solid element found on earth. Its violent reactivity is also its strength which is the characteristic harnessed in today’s lithium batteries.
2. Tesla first used commodity lithium battery 18650 cells manufactured by Panasonic in its earlier Tesla Models.
3. The Tesla Model 3 uses specially created 21700 cells manufactured (also by Panasonic in a symbiotic relationship) within the Giga Factory in Nevada, USA.
4. Cobalt is an essential element used in the making of the Tesla battery cell. However Cobalt is the most vulnerable element in the raw materials supply chain in the making of EVs. Other elements used including Nickel, Aluminum, Graphite and Silicon are more commonly found and commercially used. Half of the global Cobalt deposits are found in DR Congo where controversies such as child slavery and violence are widespread. Tesla now avoids using Congo as a source of Cobalt.
5. Tesla cell uses Nickel, Cobalt and Aluminum (NCA) as the cathode and Graphite with Silicon for the Anode.
6. With the global surge by car makers to make their own mark in the EV arena, it is foreseeable that the ramp up in battery production could make raw materials supply such as Cobalt even more vulnerable. This could pose a bottleneck in the increase of EV production and increase EV prices.
7. The Tesla Model 3 battery has evolved from the earlier battery designs. The latest cell now uses only 4.5 kg of Cobalt per car. This is way down from a initial rate of 11 kg per car in the earlier models S and X.
8. The 21700 cell is both bigger and longer than the 18650 cell. The 21700 cell is 21 mm diameter and 70 mm high (hence the numbering of the cell). Both cells have the same nominal voltage of 3.6V because the cell chemistry is the same.
9. The 21700 cell has a capacity of 4.5 AH and an energy density of 247 WH/ kg. This energy density is therefore marginally superior to the 18650 cell battery which is said to be at 240WH / kg.
10. The complete Model 3 battery has a simplified 4 modules construction. Interestingly, the 4 modules are not of the same size. The outer two modules have 23 cell groups (aka bricks) while the two inner modules have 25 cells groups. Each cell group has 46 cells in parallel. That means that the entire pack contains 4416 cells precisely configured altogether. To obtain the precise capacity and voltage of each battery, the cells need to be connected either in parallel or series. Connecting more cells in parallel increases the capacity. Connecting cell groups in series increases the battery voltage. Tesla finds this simple.
11. The whole Model 3 battery weighs 477.3 kg. The total capacity is 80 KWH and the energy density of 167 Wh /kg.
12. The battery pack is flat except for a raised portion at one end. Tesla called this the Penthouse.
13. The penthouse houses all electronic systems associated with the battery. This simplifies construction and assembly of the car.
14. Tesla’s Battery Monitoring System (BMS) is nice. BMS monitors each individual cell voltage and brick temperatures to protect the battery. Tesla now has more than 10 years experience in constructing and monitoring these batteries. The lead to each individual cell also acts as a fuse. This offers further protection for the battery.
15. The new battery pack together with its ‘penthouse’ construction could be hailed as a speedy way to construct and assemble the Model 3. This can be regarded as successfully removing one of the bottlenecks to the timely delivery of the Model 3. It certainly helps to clear the unsatisfactory massive backlog of Model 3 orders.
16. Tesla hopes to reduce cost of producing Model 3 battery to USD 100 / KWH by 2026. Having a single Giga Factory for full battery manufacturing can reduce costs. This integration of complete battery manufacturing within the car manufacturing facility gives it a marked advantage. Tesla is the only EV car maker to enjoy this advantage.
17. For most batteries, you are usually guided to charge the battery to 80-90% full level only. Also you are advised not to go below 30% level before charging up. This will help to preserve the capacity of the battery and also the life of the battery. It has been found that during charging and discharging processes, the Graphite-Silicon anode expands and collapses considerably. So avoiding the extremes of charging and discharging help to reduce this expansion and contraction of the anode. It can therefore help preserve the integrity of the anodes and therefore the life of the battery.
18. Batteries can emit a lot of heat during charging or discharging. This causes problems of overheating and failure of the battery. Tesla uses an innovative thermal (cooling) system to handle the excessive heat. Special anti-freeze liquid is circulated in specially formed flat tubes that will cool each individual cell. This permits the cells to operate at the optimum temperature.
19. During extreme cold weather, batteries lose their capacities. To enable batteries to warm up rapidly, Tesla uses heat from the induction motor, Inverter and electronics modules to heat up the thermal liquid to warm up the battery. This enables the battery to operate at optimum temperatures quickly.
20. Some research and studies into Tesla’s batteries life have found that many batteries still have 95 % remaining range after 50,000 miles usage. Even more surprising, many have 90% remaining range after 150,000 miles usage. This is reasonable especially if you consider that if you drive 15,000 miles a year, you still have a good range after 10 years of service.
21. Studies have found that 6% of cars require battery swap or change because of defects or excessive capacity range loss. Closer scrutiny of these cars have indicated that these are all cars built in 2013 and before. Many reports have indicated that Tesla can rise to the occasion whenever failures occur by quickly swapping the defective batteries.
22. Tesla is now embarking on holy grail to produce a battery which can go for one million miles before replacement.