Ok so here is something most perhaps wouldn't share.
I've made some mistakes with the charging algoritm. Or rather say ignored a potential issue.
If you remember my 500km roadtrip story a few posts back, you could see that I hit some pretty high temperatures. Here's a flashback picture to the last charging session.
When Nissan launched the 40kWh battery back in 2018, early users quickly noticed that the lack of a thermal management system could lead to the battery throttling the charge speed after rapid consecutive fastcharging sessions, aka a roadtrip scenario. This led to the term 'Rapidgate'. People complained, and Nissan eventually launched a firmware update for the LBC to allow for a bit more power at higher temperatures (at the cost of battery health).
So, how does this relate to my 40kWh battery? I've been running WITHOUT any kind of limiter, allowing for the full 125A at any temperature. Although speedy, this is unacceptable for battery longevity. So let's see how Nissan did the original 40kWh implementation. I've formatted the data in two tables, one temperature and one for the instrument cluster dash-bars.
Afaik, this is the original data pre-rapidgate fix. So this is the safest known set of parameters for quickcharging a 40kWh pack. I've tested that I can successfully manipulate the charge speed on the fly, and now taken the OEM map into use. I'm pushing this firmware update to all customers aswell.
But what's next? With some thinking, we can create sets of better maps depending on usecase.
Example 1. Say you are preparing for a long roadtrip, care about your car, want it to last a long time. You also don't care if you need to charge 5minutes longer at each stop. Then an even more relaxed parameter set would be perfect.
Example 2. Another use case, you are in a rush to get somewhere. Every minute counts, so you want to minimize time spent charging, and don't care about long term battery health. Then a more aggressive set of charging parameters could be used (temporarily hopefully!).
The possibilities here are endless, and maybe quickly switching between charging speed profiles could be the solution. I'll have to consult with my customers