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An inside look at Tesla’s P100D battery pack: more cells, 102 kWh capacity, backwards compatibility in mind

New details of Tesla’s mysterious P100D battery pack, which Tesla CTO JB Straubel once described as having notable changes in battery module and pack technology, and a “complete redo on the cooling architecture”, have emerged thanks to Jason Hughes’s latest project.
Hughes posted photos of a dismantled 100 kWh battery pack, which he obtained through the purchase of a salvaged Tesla P100D, that reveal an increase in the number of 18650 lithium-ion cells being packed within each battery module. Hughes also discovered a surprising increase in battery capacity beyond 100 kWh, and what appears to be a replaceable connector that allows Tesla to retrofit older vehicles with the newer battery pack.
More 18650 Battery Cells
As outlined in Hughes’s blog post, Tesla was able to fit more of its cylindrical 18650 lithium-ion battery cells into each of the 16 modules making up the P100D battery pack. It’s worth noting that Tesla has maintained a relatively similar form factor on battery packs produced for Model S and Model X vehicles since their introduction. Regardless of the vehicle’s model version – be it a P85, a 60, 75D, or 90D – the uniform skateboard design of the battery pack allows for ease of production, as Tesla can manufacture a single-style pack that can be installed across its fleet of vehicles. Under that same notion, Tesla has also been able to create ‘unlockable features’ by software limiting vehicle range depending on the option purchased by the customer. In other words, Tesla installs the same battery pack into like-kind vehicles (e.g. Model S 60 uses the same pack as Model S 75).

Tesla P85 battery pack module vs. P100D module [Credit: Jason Hughes via @wk057]
Hughes’s dissection of the P100D battery shows that Tesla leveraged the same design concept by distributing a total of 8,256 battery cells across the 16 modules making up the battery pack, bringing total capacity up to the advertised 100 kWh number. However, and much to Hughes’s surprise – he had previously criticized Tesla for providing less battery capacity than what’s perceived by way of the vehicle’s nameplate – Tesla actually provided 102.4 kWh of capacity on the P100D pack, representing a 2.4% increase over what’s marketed.
Backwards Compatible Design
Tesla has also, seemingly, taken into account the ability to retrofit new battery packs onto older vehicles by using the same high and low-voltage connectors across packs. According to Hughes, “the pack itself has the same high-voltage connection, the same low voltages connectors, and the same cooling connector.” However, Hughes notes that there’s subtle changes on the P100D pack that would require a new part in order for it to be retrofittable onto non-P100D vehicles.
“The [P100D] pack has the newer ring around the high-voltage connector. So, it’s plug-and-play (for the most part, firmware and config changes needed) on the Model X and refreshed Model S, however it would require a different spacer ring on the high voltage connector. Tesla even has a part number for it, so it should be pretty simple to put into any Model S/X.” says Hughes.
What about that new P100D battery cooling architecture?
Well. It’s not magic. Tesla did improve battery cooling in the new P100D 100 kWh battery pack. And Tesla did provide a redone architecture, but it isn’t one of mythical proportions.
Hughes reveals Tesla’s approach to improve battery pack cooling was to use shorter and thinner cooling loops per battery module, thereby improving the rate of heat dissipation. Unlike most other electric car makers who do not “prime” their vehicle’s batteries through the use of a thermal management system, Tesla pumps fluid through the battery module to regulate the temperature of its battery pack in order to bring them to optimal operating temperatures. By ensuring the lithium-ion cells operate within ideal temperatures, Tesla is able to provide the best performance possible, while ensuring cell longevity.

Tesla P100D battery module cooling loops [Credit: Jason Hughes]
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Armored Tesla Cybertruck “War Machine” debuts at Defense Expo 2025
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News
Tesla Megapacks chosen for 548 MWh energy storage project in Japan
Tesla plans to supply over 100 Megapack units to support a large stationary storage project in Japan, making it one of the country’s largest energy storage facilities.

Tesla’s Megapack grid-scale batteries have been selected to back an energy storage project in Japan, coming as the latest of the company’s continued deployment of the hardware.
As detailed in a report from Nikkei this week, Tesla plans to supply 142 Megapack units to support a 548 MWh storage project in Japan, set to become one of the country’s largest energy storage facilities. The project is being overseen by financial firm Orix, and it will be located at a facility Maibara in central Japan’s Shiga prefecture, and it aims to come online in early 2027.
The deal is just the latest of several Megapack deployments over the past few years, as the company continues to ramp production of the units. Tesla currently produces the Megapack at a facility in Lathrop, California, though the company also recently completed construction on its second so-called “Megafactory” in Shanghai China and is expected to begin production in the coming weeks.
READ MORE ON TESLA MEGAPACKS: Tesla Megapacks help power battery supplier Panasonic’s Kyoto test site
Tesla’s production of the Megapack has been ramping up at the Lathrop facility since initially opening in 2022, and both this site and the Shanghai Megafactory are aiming to eventually reach a volume production of 10,000 Megapack units per year. The company surpassed its 10,000th Megapack unit produced at Lathrop in November.
During Tesla’s Q4 earnings call last week, CEO Elon Musk also said that the company is looking to construct a third Megafactory, though he did not disclose where.
Last year, Tesla Energy also had record deployments of its Megapack and Powerwall home batteries with a total of 31.4 GWh of energy products deployed for a 114-percent increase from 2023.
Other recently deployed or announced Megapack projects include a massive 600 MW/1,600 MWh facility in Melbourne, a 75 MW/300 MWh energy storage site in Belgium, and a 228 MW/912 MWh storage project in Chile, along with many others still.
What are your thoughts? Let me know at zach@teslarati.com, find me on X at @zacharyvisconti, or send us tips at tips@teslarati.com.
Tesla highlights the Megapack site replacing Hawaii’s last coal plant
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Elon Musk responds to Ontario canceling $100M Starlink deal amid tariff drama
Ontario Premier Doug Ford said, opens new tab on February 3 that he was “ripping up” his province’s CA$100 million agreement with Starlink in response to the U.S. imposing tariffs on Canadian goods.

Elon Musk company SpaceX is set to lose a $100 million deal with the Canadian province of Ontario following a response to the Trump administration’s decision to apply 25 percent tariffs to the country.
Starlink, a satellite-based internet service launched by the Musk entity SpaceX, will lose a $100 million deal it had with Ontario, Premier Doug Ford announced today.
Starting today and until U.S. tariffs are removed, Ontario is banning American companies from provincial contracts.
Every year, the Ontario government and its agencies spend $30 billion on procurement, alongside our $200 billion plan to build Ontario. U.S.-based businesses will…
— Doug Ford (@fordnation) February 3, 2025
Ford said on X today that Ontario is banning American companies from provincial contracts:
“We’ll be ripping up the province’s contract with Starlink. Ontario won’t do business with people hellbent on destroying our economy. Canada didn’t start this fight with the U.S., but you better believe we’re ready to win it.”
It is a blow to the citizens of the province more than anything, as the Starlink internet constellation has provided people in rural areas across the globe stable and reliable access for several years.
Musk responded in simple terms, stating, “Oh well.”
Oh well https://t.co/1jpMu55T6s
— Elon Musk (@elonmusk) February 3, 2025
It seems Musk is less than enthused about the fact that Starlink is being eliminated from the province, but it does not seem like all that big of a blow either.
As previously mentioned, this impacts citizens more than Starlink itself, which has established itself as a main player in reliable internet access. Starlink has signed several contracts with various airlines and maritime companies.
It is also expanding to new territories across the globe on an almost daily basis.
With Mexico already working to avoid the tariff situation with the United States, it will be interesting to see if Canada does the same.
The two have shared a pleasant relationship, but President Trump is putting his foot down in terms of what comes across the border, which could impact Americans in the short term.