Differences

This shows you the differences between two versions of the page.

--- electrical:12v:eternal_absorption [2020/07/08 12:08]
frater_secessus created
+++ electrical:12v:eternal_absorption [2021/05/05 11:00]
frater_secessus [workarounds]
@@ Line 1: / Line 1: @@
-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.
-====== insufficient Absorption ======
-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.
+[[lifestyle:words_of_wisdom|Words of wisdom]]:
+> "As long as... you cycle the battery daily, you could set float voltage to [Vabs] too without worry. Only when you stop cycling the battery do you need to return float voltage to more regular 13.2v levels." -- sternwake((http://www.cheaprvliving.com/forums/showthread.php?tid=20022&pid=229883#pid229883))
+====== dealing with insufficient Absorption ======
+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.
 Causes of insufficient Absorption:
@@ Line 11: / Line 17: @@
   * solar conditions - not enough good sun long enough to finish Absorption
-===== set Vfloat to Vabs =====
+===== workarounds  =====
+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:
+  * 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.
+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.
-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.
+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.
@@ Line 25: / Line 47: @@
 ===== gotchas =====
-  * 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.

RV and vandwellers wiki

User Tools

Site Tools

Differences

Page Tools