Some more LFP questions

[Jman]

After reading more on LFP i have a few questions i cant find the answers to.

1 Why should temperature compensation be disabled?

2 Its said on this forum by some that bms boards are big cause of failure if not number1. Why is this exactly?

3 when setting custom absorption and float voltages in my CC (victron mppt 100/50), how does the CC know if its a lead or lithium battery? Does the CC determine this by the slight difference in resting voltage? eg lead 12.6v vs. Lithium 13v.

[Mike90250]

After reading more on LFP i have a few questions i cant find the answers to.

1 Why should temperature compensation be disabled?

Because the LFP does not require it.

2 Its said on this forum by some that bms boards are big cause of failure if not number1. Why is this exactly?

the BMS boards are poorly engineered, and use the very cheapest parts that can easily fail.

3 when setting custom absorption and float voltages in my CC (victron mppt 100/50), how does the CC know if its a lead or lithium battery? Does the CC determine this by the slight difference in resting voltage? eg lead 12.6v vs. Lithium 13v.

the CC only knows what you program into it. It cannot tell the difference between a full FLA battery or a low LFP battery

[Jman]

the CC only knows what you program into it. It cannot tell the difference between a full FLA battery or a low LFP battery

So what is the point in being able to adjust the absorb and float voltages in the simple user interface if you cant set the battery type? It says save your own presets. My guess is they are for lead acid still.


One more question.
When charger hits absorption voltage should i switch to power supply mode to avoid overcharging? Whether solar controller or ac charger. As in CV mode the charger will not be able to know when the battery is fully charged when there is a load on battery. Well that is my plan since there is no way to program that in my chargers.

[Mike90250]

So what is the point in being able to adjust the absorb and float voltages in the simple user interface if you cant set the battery type? It says save your own presets. My guess is they are for lead acid still.......

Presets are presets. Set them properly and with knowledge of what you are doing, and how the batteries need to be charged. Type of chemistry does not mater if you are manually setting voltages and times

[Jman]

Presets are presets. Set them properly and with knowledge of what you are doing, and how the batteries need to be charged. Type of chemistry does not mater if you are manually setting voltages and times

I still don't understand if a LFP battery is flat around the same voltage as when a lead acid is full. What else can be done from the standard user interface so the CC knows the difference? I can't see anyway to set the voltage for when the charger should start a cycle.

[Mike90250]

I still don't understand if a LFP battery is flat around the same voltage as when a lead acid is full. What else can be done from the standard user interface so the CC knows the difference? I can't see anyway to set the voltage for when the charger should start a cycle.

You CANT'T use the standard interface, you configure custom setpoints. The factory settings are "close" but never actually match the plethora of different Mfg's setpoints.

[Jman]

You CANT'T use the standard interface, you configure custom setpoints. The factory settings are "close" but never actually match the plethora of different Mfg's setpoints.

Ok Mike I see what you mean now. Well looking here which seems to cover my CC, I'm lost. Wish they would have a simply approach in the UI instead of code jargon.