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opinion:frater_secessus:chariging_lithium_to_soc [2022/05/23 13:21]
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opinion:frater_secessus:chariging_lithium_to_soc [2022/05/23 13:23]
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| Charging lithium to <100% is easy; just lower charging voltage. Charging lithium to some specific and consistent target (30%, 50%, 80%, whatever) is notoriously difficult with solar as charging conditions are highly variable. This is not an issue if you are using 10A out of the 50A overnight; you will have plenty of safety net whether you charge to 40% or 90%. So play with lower charging voltages and with absorption times to see what keeps us in the sweet spot. | Charging lithium to <100% is easy; just lower charging voltage. Charging lithium to //some specific and consistent target// (30%, 50%, 80%, whatever) is notoriously difficult with solar as charging conditions are highly variable. This is not an issue if you are using 10A out of the 50A overnight; you will have plenty of safety net whether you charge to 40% or 90%. So play with lower charging voltages and with absorption times to see what keeps us in the sweet spot. |
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| It is an issue if you need to pull 30A out of the 50A bank overnight: leaving ≥20% SoC by morning means you'd have to go into sundown with ≥80% SoC. Not so much wiggle room there. In that scenario I might charge-and-stop to ~14v (or whatever consistently yields 100% SoC with your system), minimal/no absorption duration, then play with lower floats like ~13.35v to see where SoC settles. | It //is// an issue if you need to pull 30A out of the 50A bank overnight: leaving ≥20% SoC by morning means you'd have to go into sundown with ≥80% SoC. Not so much wiggle room there. In that scenario I might charge-and-stop to ~14v (or whatever consistently yields 100% SoC with your system), minimal/no absorption duration, then play with lower floats like ~13.35v to see where SoC settles. |
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| A more precise way to do it would be to use a controller that talks to a shunt and could hold the bank at a given SoC based on coulomb-counting. Should be doable with pi or arduino, or maybe some of the more network-centric gear like Victron already has that functionality. I imagine in a few years the feature will be commonplace. | A more precise way to do it would be to use a controller that talks to a shunt and could hold the bank at a given SoC based on coulomb-counting. Should be doable with pi or arduino, or maybe some of the more network-centric gear like Victron already has that functionality. I imagine in a few years the feature will be commonplace. |
