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electrical:12v:eternal_absorption [2020/07/08 15:01] frater_secessus [gotchas] |
electrical:12v:eternal_absorption [2020/09/23 15:59] frater_secessus [workaround] |
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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====== dealing with insufficient Absorption ====== | ====== dealing with insufficient Absorption ====== |
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In off-grid solar charging scenarios batteries are most often damaged by [[electrical:batterycide|chronic undercharging]]. Specifically, not holding the [[electrical:solar:charge_controller_setpoints|manufacturer's recomended Absorption voltage]] (Vabs), and not holding that voltage long enough((duration)) for acceptance to drop to endAmps. | In off-grid solar charging scenarios batteries are most often damaged by [[electrical:batterycide|chronic undercharging]]. Specifically, not holding the [[electrical:solar:charge_controller_setpoints|manufacturer's recommended Absorption voltage]] (Vabs), and not holding that voltage long enough((duration)) for acceptance to drop to endAmps. |
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Causes of insufficient Absorption: | Causes of insufficient Absorption: |
* 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 ===== |
| See: [[electrical:severe_battery_use#increasing_effective_absorption_duration|increasing effective Vabs duration through increased voltage]]. |
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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. | 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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