Charge start/stop feature request for better lithium longevity?
Hi, please vote and indicate if you think this is a good idea. I'm trying to figure out how to make it a formal feature request with SunSynk.
Problem: Constant small recharges to 100% SoC isn't ideal for Lithium. Running lithium in the middle of its capacity does the less damage versus deep discharge or keeping it highly charged.
The suggested UI feature when the Lithium Batt type is selected (quick mockup screen):
Charge stop: to cut off the grid and PV charging the battery at user defined level.
Default: 100% (most users unaware of LFP degradation risks near full charge will prefer seeing 100%, but for some of us that are more knowledgeable, at least we can change this default).
This is similar to the "ShutDown" SoC % setting for discharge, but just the other side of the charge cycle.
E.g. I'd set 95% and give my lithium less stress.
Charge restart: to trigger allowing resuming charging of battery from PV or grid until a charge stop threshold is reached.
Default: 96% (this is what lenovo do). Or 99% to more or less keep it behaving as aggressively as it does now.
This is similar to the "Restart" SoC % setting for discharge, but for charge instead.
E.g. I'd set 90% and give my lithium less stress.
Full charge freq.: to ensure LFP is occasionally charged to 100% so that internal BMS cell balancing can occur.
Default: 1 days (once per day).
This is slightly similar to the equalisation setting, but instead of applying an equalisation voltage, it's a step to ensure 100% SoC charge cycle so BMS can get a chance to perform equalisation.
E.g. I might set mine to 7 days.
Problem it should solve/mitigate (I don't like seeing my batter get thrashed up to 100% like this just because PV isn't strong enough to cover some daytime loads):
There's lot of detail about why this would be useful in an overly long forum post before: https://www.sunsynk.org/forum/techical-support/how-to-prolong-lithium-battery-life-overspec-a-bit-the-rest-of-the-tweaking-is-maybe-not-worth-the-complexity. But few people will have time to trawl long posts, to this is the short version.
I also support this but think it should be volt based not %, % is far to randome and wont work well with a LIFEpo4 charge curve. its quite obvious that sunsynk arnt taking any of this on board tho!