Charge cycle for LiFePO4

I want to confirm what should happen.
So I have a 24 V Smart LiFePO4 system
The Smart MPPTs are externally controlled by the Smart BMS.

Lets start the example with the batteries in say 50% and SoC 70%. So time to charge them!

When Sun goes up the batteries will be charged Bulk/Absorb (Same thing) until they reach 100%.
In my case Charge Voltage = 28.0. Tail = 3%. Time = 3 min.

After this the MPPTs will stay in Absorb for the "Absorb time" set up in Smart BMS = 2h.
In my case the Voltage goes up to 28.4 during this period but the charge current drops to zero.After this the MPPT will drop to Float = 27.0 Volt.

When the SoC drops below SoC treshold (70%) a new Bulk/abs cycle will be started.
Normally after a day or two.

Balancing: Every 14 day or so the batteries will be kept at 24.8 until balanced.

Sudden load: If a sudden load make the voltage drop it does not have any effect. The MPPT will stay in float mode maintaining 27.0 V.

Is this the way it is supposed to work????

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kevgermany ♦♦ commented · Nov 15, 2023 at 06:00 AM

You can't have two SOCs at the same time. Batteries should be at the same state of charge.

What else is in your system?

Are you using ESS?

In general as soon as there's load on the system the MPPTs should output to cover the load. Batteries will be kept at 100% as long as there's enough solar power.

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