People will not trust batteries that have to be constantly online

Part of Onboard BMS should estimate battery’s State-of-Health independently from the cloud.

When we consider estimating battery parameters in the cloud and sending them to the batteries, apart from risks and efficiency, we should also think about trustworthiness of this architecture. Today, when people buy new cars, they still often choose gasoline over electric cars because they might believe that EVs are less reliable and less predictable than vehicles running on fuel (even though this is not true anymore). It will definitely not help to instil trust in electric technology if we tell people that in order to work reliably, the battery in their vehicle must periodically receive some information from the internet.

Here's an example of real customer's testimonial (translated from Russian):

Everything is fine with EVs, except one thing — its "brain". It's a computer that really wants to access the internet. I'm not sure about other automakers, but Tesla's ability to update firmware over-the-air and the theoretical ability to deactivate the battery is a factor that repels me from buying such cars. [...]

At the moment, the total number of electric vehicles and appliances in operation is a small fraction of the number of vehicles with internal combustion engine and gas appliances. Electric products will win more market share if they look more attractive compared to old, non-electric alternatives, not if they look more attractive compared to other electric products. And electric power generation for the grid is so much more efficient than fuel or gas combustion that even with the current, relatively inefficient grid and the current share of coal and gas power plants in countries such as America, any electric machine is much more economical than any combustion machine, both in terms of money and CO2 emissions. As Saul Griffith frequently points out, if America magically converted to using only electric cars and appliances today, it would emit two times less CO2 right away:

https://lh3.googleusercontent.com/yJCemsY4TdOLQaKLtBw1kETwvRU1_8kYQ4_WRQ0jw-BakZRFQeOZWhdylcQi81bwwPpq7Kr9O7_tZoL_smT9LdlT5uDSfXinqwkrAM1n7ClEr_ldGV_XCEJVZoqQON-8SPKocf49

So, it’s reliability and trustworthiness, not energy or money efficiency that still makes some people to buy new gasoline cars and gas appliances instead of electrical alternatives. This observation together with the point made above about the market for electric machines leads to the following conclusion: companies that make batteries and electric machines should prefer making their technology as reliable and trustworthy as possible (thus maximising the adoption rate, all else being equal) even at the cost of some efficiency losses.

The capacity to work offline is one of the factors of the technology Trustworthiness: cf. local-first software and Offline First initiative.