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--- opinion:frater_secessus:endamps [2021/05/05 11:36]
frater_secessus [WTF does that even mean?]
+++ opinion:frater_secessus:endamps [2021/05/05 11:54] (current)
frater_secessus [WTF does that even mean?]
@@ Line 1: / Line 1: @@
 Note:  Flooded, AGM and gel are all types of lead-chemistry battery.
-====== How do I know when my lead battery fully charged? ======
+====== How do I know when my lead battery is fully charged? ======
 Lead batteries are [[electrical:batterycide|killed]] by 'dwellers [[electrical:12v:psoc|undercharging]] them:  not fully, and/or not often enough.  To reach the expected cycle lifetime((at a given [[electrical:depth_of_discharge|depth of discharge]])) a lead battery must be charged:
@@ Line 10: / Line 10: @@
 So how do we know when the battery is fully charged?  When I have topped it off for 15 minutes from the alternator?  (bzzzt) When the controller drops to Float? (bzzzt) When it is above 12.7v?  (bzzzt)
-**A lead battery is charged when acceptance at Absorption voltage has dropped to a specified value.**
+**A lead battery is charged when acceptance at Absorption voltage has dropped to a small fraction of its rated capacity.**
 ===== WTF does that even mean? =====
@@ Line 20: / Line 20: @@
 //Acceptance// is the amount of **charge current** the battery bank is accepting. Since there may be loads this may not be the same amount the charger(([[electrical:solar:charge_controller|solar charge controller]], [[electrical:12v:b2b|dc-dc]], [[electrical:converter|converter]], whatever)) is putting out.
-Example: the charger is putting out 10A.  Loads (laptop, lights) are consuming 6A.  The bank's acceptance is 4A. (10A - 6A - 4A).
+Example: the charger is putting out 10A.  Loads (laptop, lights) are consuming 6A.  The bank's acceptance is 4A. (10A - 6A - 4A).  It //must// be;  chargers only put out what the system will take.((or else voltage would keep rising))
 The presence of loads can make assessing acceptance tricky, which is why we watch current going in/out of the bank with a [[electrical:12v:battery_monitor|battery monitor]] (shunt or clip-on meter).
@@ Line 30: / Line 30: @@
-> has dropped to a specified level.
+> has dropped to a small fraction of its rated capacity
-This is where the battery monitor shines.  Lead battery manufacturers typically specify Absorping until acceptance is some small percentage of [[electrical:12v:battery_capacity|bank capacity]] (C).
+Lead battery manufacturers typically specify Absorping until acceptance is some small percentage of [[electrical:12v:battery_capacity|bank capacity]] (C). These values can be expressed in different forms but they all mean the same thing:
-These values can be expressed in different forms but they all mean the same thing:
 ^ fraction       ^ percentage      | **decimal**      | **actual values for 100Ah bank**  |
 | C/200 - C/100  | 0.5% - 1% of C  | 0.005C - 0.010C  | 0.5A - 1A                         |
+As you can see the Amps in question are quite small;  this is why a battery monitor is important.
+===== putting it all together =====
+Battery X (100Ah) is fully charged when the battery is only accepting 0.5A to 1A at 14.5v.((Totally made-up example.  Follow the charging specs your battery manufacturer publishes.))
@@ Line 45: / Line 52: @@
 A deep-cyle battery discharged to 50% typically takes [[opinion:frater_secessus:charging_faster|several hours at Vabs]] to fully recharge.
-===== putting it all together =====
-Battery X (100Ah) is fully charged when the battery is only accepting 0.5A to 1A at 14.5v.

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