I’m toying with my old camping battery, it’s an aliexpress golf car battery. I’ve added a arduino based monitor. Because sometime the battery just shutdwon, the inegrated screen always says 90% not problem with my electric cooler… lol my beers are not cold anymore !
Your battery monitor tries to "correct" its charge estimate by peeking at the voltage. But LiFePO4 batteries (assuming this is what you have because of LFP in the variables's name) hold a nearly constant voltage until they're almost dead — so the voltage always looks fine, and the monitor keeps resetting its reading to ~90%. Then the battery suddenly dies with no warning.
Your code already tracks amps flowing in and out over time — that's the right way to do it and you should stick with that. The problem is the code also has a voltage check that periodically "corrects" the reading, and since LiFePO4 voltage always looks fine until the battery is nearly dead, it just keeps resetting back to 90%. Try disabling or limiting that voltage correction so the amp tracking can do its job uninterrupted.
If it’s a good deep sleep mode on a good board, then the current consumption might be really really small… IOT devices get 2 year of lifetime on small coin batteries…
It looks like a classic Nano from the picture. You can free an extra 1.5kB of flash memory by treating it as Uno instead. They both have exactly the same chip (atmega328p) and this identity change can be done with the "burn bootloader" procedure. For historical reasons the Nano reserves 2kB for the bootloader although now only 512B is used.
