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electrical:12v:eternal_absorption [2020/07/08 15:02] frater_secessus [dealing with insufficient Absorption] |
electrical:12v:eternal_absorption [2021/05/05 11:00] frater_secessus [workarounds] |
Note: this is for deep cycle lead chemistries only.! Lithium chemistries should not be held at full voltage. | Note: this is for deep cycle lead chemistries only! Lithium batteries should not be held at full voltage. |
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* solar conditions - not enough good sun long enough to finish Absorption | * solar conditions - not enough good sun long enough to finish Absorption |
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===== workaround ===== | ===== workarounds ===== |
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The Eternal Absorption approach completely forgoes Float stage, forcing the controller to stay in Absorption by **setting Vfloat to Vabs**. This addresses the controller issues above. It will not address the insolation problem on a given day, but extended Absorption will help reduce damage from previous days of poor harvest. | While you may not be able to increase the //actual// duration,((as when the controller setpoint is maxxed out)) you can achieve a similar effect with one or more of these techniques: |
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| * if duration setpoint is maxxed then **set Vfloat == Vabs**. Absorption duration will effectively be "until the sun goes down". |
| * **charge at a lower current** (charging minimum). While [[opinion:frater_secessus:charging_faster|overall charging will take about the same amount of time]], Bulk's share of that time will increase and [[electrical:12v:charging#absorption|Absorption will take somewhat less time]]. |
| * **Absorb at a higher((but still manufacturer-sanctioned)) voltage** (Vabs), this will decrease Absorption duration. Keep a close watch on water levels for flooded batts, and also mind the max allowable voltage for AGM/Gel. |
| * **Float at a higher((but still manufacturer-sanctioned)) voltage** (Vfloat). |
| * [[electrical:12v:alt_and_solar|supplement]] solar charging with another charging source during Bulk, allowing more time for solar to finish absorption. |
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| Some controllers/chargers have a "restart Absorption" option allows one to override Float and get more time at Vabs. Best use of this feature would be to look at the controller display a few minutes before the Absorption timer is due to expire. If acceptance is good let it go. If acceptance is too high give the bank another round of Absorption. |
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| If those approaches are insufficient, //Eternal Absorption// approach completely forgoes Float stage, forcing the controller to stay in Absorption by **setting Vfloat to Vabs**. This addresses the controller issues above. It will not address the insolation problem on a given day, but extended Absorption will help reduce damage from previous days of poor harvest. |
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===== gotchas ===== | ===== gotchas ===== |
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* increased Vabs duration will require more frequent watering, due to increased outgassing | * increased Vabs duration may require more frequent watering, due to increased outgassing.((but see [[http://bdp.mousetrap.net/index.php/2020/09/18/watered-batteries-after-three-weeks-of-eternal-absorption/|this blog post]] which suggests no dramatic increase)) |
* calcium-enhanced batteries (typically starter batteries and some hybrid "marine" batteries) can be damaged((positive grid corrosion)) by long periods of excess voltage. The question is which is worse for them: chronic undercharging or grid corrosion from higher voltage. Pick your poison. | * calcium-enhanced batteries (typically starter batteries and some hybrid "marine" batteries) can be damaged((positive grid corrosion)) by long periods of excess voltage. The question is which is worse for them: chronic undercharging or grid corrosion from higher voltage. Pick your poison. |
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