You know of an actual study
Do a search for dendrites on Lifepo cells. Dendrites are the key to understanding when or not to float.
Perhaps you can treat your LFP just like LA, then report back in a year or two.2 of those don't to have anything to do with LFP. The third I don't what it is saying.
But none have any info about conditions to be able to relate how we would use a battery.
Peter, other than internal wiring between cells that might effect max charge/ discharge current, I wonder why there would be any differences between assemblers other than differences in opinion. Seems like the chemistry should be the same regardless of who wires the cells together, but I'm likely missing something.My batteries are Lion Energy. They have a much lower charge recommendation than others such as Battle Born (13.9v). I queried them to make sure I understood correctly. They confirmed, but I must add that the tech didn't seem particularly knowledgeable. They also seem a bit ambivalent about charging.
My point being is not all LFP batteries will carry the same charge recommendations. That said, I take TT at his word about no-float as a guardrail for LFPs due to their chemistry. I don't understand why but will accept the guidance. There's a point where discussions like this induce sleep-like behavior in me. I didn't get the right brain cells I suppose.
Peter View attachment 142792
Perhaps you can treat your LFP just like LA, then report back in a year or two.
So what does your manufacturer say about floating?What xxxx statement! I have had my LFP for 10 months and treat them as the manufacturer says to.
You would need to watch a few Will Prowse Youtube as I do not remember the correct terms. He points out that same/similar cells are controlled by a variety of different BMS and associated hardware, circuit boards. Seeing it while he is explaining is priceless.Peter, other than internal wiring between cells that might effect max charge/ discharge current, I wonder why there would be any differences between assemblers other than differences in opinion. Seems like the chemistry should be the same regardless of who wires the cells together, but I'm likely missing something.
TT, thoughts?
Thanks.You would need to watch a few Will Prowse Youtube as I do not remember the correct terms. He points out that same/similar cells are controlled by a variety of different BMS and associated hardware, circuit boards. Seeing it while he is explaining is priceless.
we are talking LFP, "float" is not more than 100% SOC voltage
I found my info and am moving on
Do you mind sharing?
I think the question of what SOC LFP should be "stored at" is different from whether they will lose capacity if floated. I don't think there is much debate on the disadvantage of letting them sit off a charge source at 100% SOC. Floating at a voltage low enough not to increase SOC but that can supply transient power needs could be applied to a battery at 100%, 75% or 30% SOC. Constant float voltage above that level that increases SOC being bad is also not controversial.So I asked the same question on other forums looking for separating myth from fact.
Being clear here that when we say "float" on a LFP battery we are saying to hold no more that 100% SOC voltage.
Have now seen 2 actural test papers about storing Lithium batteries and the effect that SOC has on the capacity.
The answer from the tests is YES storing at 100% does reduce capacity. It in fact DOUBLES the loss over storing at 30% SOC. But that only means a 2% loss and far as I am concerned that is meaningless in the practical user world of the battery.
Don. What is the definition of storage per the papers. I mean to me storage is putting the fully charged battery on a shelf.So I asked the same question on other forums looking for separating myth from fact.
Being clear here that when we say "float" on a LFP battery we are saying to hold no more that 100% SOC voltage.
Have now seen 2 actural test papers about storing Lithium batteries and the effect that SOC has on the capacity.
The answer from the tests is YES storing at 100% does reduce capacity. It in fact DOUBLES the loss over storing at 30% SOC. But that only means a 2% loss and far as I am concerned that is meaningless in the practical user world of the battery.
I think the question of what SOC LFP should be "stored at" is different from whether they will lose capacity if floated. I don't think there is much debate on the disadvantage of letting them sit off a charge source at 100% SOC. Floating at a voltage low enough not to increase SOC but that can supply transient power needs could be applied to a battery at 100%, 75% or 30% SOC. Constant float voltage above that level that increases SOC being bad is also not controversial.
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When I started the topic I was more interested in whether it was ok to get to "float" everyday of 13.6V, hold it all afternoon on solar, discharge with use at night, cycle the battery back up the next, repeat over and over. Still have not found a study of that.
I think the reason you aren't finding exactly what you are looking for is because the fundamental issue is storage at various SOCs, and that has been studied extensively. I
Bingo.I think the reason you aren't finding exactly what you are looking for is because the fundamental issue is storage at various SOCs, and that has been studied extensively. It's then a simple relationship between how you set a float voltage and the resulting SOC that gets maintained. It's not worthy of a study. If you set the float voltage above the 100% SOC open circuit voltage of the cells they will continue to charge and be ruined. If you set the float voltage at the 100% SOC open circuit voltage of the cells, the batteries will stay at 100%. If you set the float voltage at the 70% SOC open circuit voltage, it will hold the batteries at 70% SOC. The whole goal of float with LFP is to act as a power supply to power loads without raising or lowering the battery SOC.