Poida MPPT setting changes for LiFePo?

Author	Message
poida Guru Joined: 02/02/2017 Location: Australia Posts: 1442	Posted: 03:03am 17 Dec 2024         Revlac said   .. it stayed in mppt mode then cut power for a moment then continued charging and repeating,  this went on most of the day, it eventually went into absorb mode most of the next day ... I think this is the result of the mppt being in MPPT mode. This mode will include a mppt scan every minute, and this is a search for the PWM width that gives the highest output power WHILE NOT EXCEEDING absorb Bv and max output current. But it does exceed it, not for long, maybe only 0.1 second due to the search needing to receive the output current and battery voltage as soon as the new PWM width is programmed. There are time lags and I designed the code to work with lead acid which has a large capacity for these things. LI might not like it. I think the quick search, connecting the battery to short periods of different PWM widths and large output currents might be bringing the LI battery above absorb voltage, and so then the mppt sees this and shuts down. Maybe a minute later Bv is less than Absorb voltage and it restarts, using MPPT mode as the starting point. so more mppt scans, more over voltage for a moment and more shutdowns. this is just my first idea of what might be going on. I could make a few new settings to look after LI batteries. LI battery owners can help here. maybe a "is it LI", if so, then no mppt scans once Bv gets close to absorb and we choose how close is close. Maybe also if it's LI, then the mppt scan will go really slowly, but only every 10 minutes, when Bv is close to absob. I am open to the idea of making the code work well with LI.