That’s the point. If you set your float voltage to allow your solar to power a load connected to a fully charged Li battery then your float voltage is high enough to impress a voltage on the battery. That’s a charger , small yes. But that’s the point
For a 100AH Battery Pack, the 1C Rate is 100A, the 0.5C Rate is 50A. A 280AH has a 1C of 280A & 0.5C of 140A.
This refers to the ratio between capacity of battery and charge current
Nope. You failed. This paper does not compare DoD to other factors in cycle life. You said DoD was the dominant factor. I said (and the paper I quoted said) that it was far less impactful than time and temperature. Try again.Everyone can point to research
“This is explained by the well-known observation that cycling at higher SOC leads to more pronounced SEI generation compared to lower SOC cycling [32, 37, 38]. The cycling at 50% DOD leads to a longer duration at high SOC ranges (compared to 100% DOD) of the cells with more electrolyte and salt decomposition. Furthermore, an important difference between the 50% DOD cycling and the 100% DOD cycling is the number of charge–discharge cycles. One cycle for the 50% DOD cells represents 1.25 Ah cycle−1, leading to roughly 1600 cycles until EOL, while for the 100% DOD cells (2.5 Ah cycle−1) only about 800 cycles are performed until EOL is reached
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Influence of cycling profile, depth of discharge and temperature on commercial LFP/C cell ageing: post-mortem material analysis of structure, morphology and chemical composition - Journal of Applied Electrochemistry
Abstract The paper presents post-mortem analysis of commercial LiFePO4 battery cells, which are aged at 55 °C and − 20 °C using dynamic current profiles and different depth of discharges (DOD). Post-mortem analysis focuses on the structure of the electrodes using atomic force microscopy (AFM)...link.springer.com
Simply because the watts the chargecontroller is supplying matches the load on the batteries.
Well goneboating explains (kinda makes sense) that even impressing a voltage on a cell can cause small amounts of damage to a cell if the cell doesn’t need to be charged. But that’s being nit picky to say the least. Also I can’t understand any other way to allow our batteries to constantly supply power to our homes constant loads. Other than constantly allowing the charge controller to impress a voltage because a voltage has to be present from the chargecontroller so it can constantly supply power to the homes constant loads so that pv power can be used so that battery doesn’t have to be used/short cycled..
By this logic just putting cells in parralel is abusive.
The important qualifier in that statement is "if the cell doesn't need to be charged". A cell doesn't need to be charged if the cell was charged to 3.65 volts. If we follow the OPs practice of charging to 3.45 volts and applying a voltage at 3.35 volts I have not seen any reason to change my strategy.
I never heard the direct answer to this question? @Goboatingnow , Can you give us a little background on your system and how long you have been using Lithium batteries?
I’m not sure either. I guess a cell is full at its resting full voltage. Either way it’s being to nit picky
Yeah so once the cells are balanced then I can’t see paralleling them would cause any degradation. I mean I suppose if the cells each lost capacity at different rates then the transfer of power between the cells could cause very very minimal degradation.. but if each cell lost capacity at the same rate... I mean what are we talking about lol.. nothing that matters for our setups
Its unlikely that any 2 cells will have an identical internal resistance profile so there will be eddy currents.
Actually the OP did not ask for those things, he suggested a charging strategy that most people who have been using Lithium for years agree with. Good luck with your "highly instrumented test system". Let us know when you get around to implementing it. Maximum life and minimum stress were the context in which his suggestions were framed. I don't think he intended for the discussion to extend to stress at the level of the SEI layer, but we don't know because he has not been heard from for over six months.
I have seen examples of cells at significantly different SOCs present the same resting voltage. Case in point is the people that get new cells delivered which all test within 0.001 volts, put them in a pack and when they reach the knee of the curve they diverge significantly.
diysolarforum.com
I have evolved from an e bike conversion 12 years ago using Headway cells to my current pack of 42kWhs of LFP. I have used conservative settings as advocated by the OP in his first post at the top of this thread. . My experience has been good even though I have made mistakes along the way. I have been pleased with the longevity of the various cells that I have used and resold over the years.
So I’m interested in your thoughts. What do you recommend for a use case like mine
Careful. Don't feed the beast.
