Solar Charge Controller and Lithium Batteries

[carawlins]

Hello Everyone! This is my 1st post here.

Is it true that if you have lithium batteries, solar panels and a solar charge controller that it is prudent to disconnect the solar panels to lower the incidences of charge cycles, and prolong battery life? I would think a solar charge controller (I have a Victron MPPT 100/30) would handle this without disconnecting the panels. Any comments? Thanks!

 

[MisterSandals]

is prudent to disconnect the solar panels to lower the incidences of charge cycles, and prolong battery life? I would think a solar charge controller (I have a Victron MPPT 100/30) would handle this without disconnecting the panels.

Welcome!

Normally I'd say "no, this is what an SCC is meant to do". But...

There is a case that you seem to suggest that is called "micro-cycling" and I try to minimize this myself.
I consider micro-cycling to be when you finish a charge cycle, the battery voltage will settle to some resting voltage. Lets say you charge to 14.0V and in 10 minutes your battery settles to 13.4V (mine settle here at 3.35Vpc). If your SCC is programed with the Victron LiFePO4 charge profile, it will begin a new charge cycle up to 14.0V. Rinse and repeat.

I use a custom charge profile where i have the float set a few hundredths of a volt below where my cells settle (like 3.32Vpc). This greatly reduces the micro-cycling.

How much this actually prolongs the life of the batteries, i dunno. Its gotta help to some extent. It makes me feel better and will likely extend my life.