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--- opinion:frater_secessus:healthy_agm [2022/11/08 23:53]
frater_secessus created
+++ opinion:frater_secessus:healthy_agm [2022/11/09 00:08] (current)
frater_secessus
@@ Line 6: / Line 6: @@
 In The Beginning, emergency backup power for industrial purposes was done with [[electrical:12v:deep_cycle_battery#fla_-_flooded_lead_acid|Flooded Lead-Acid]] batteries (FLA) and [[electrical:inverter|inverters]].  It worked well at the time, but there are drawbacks:
-  * FLA batteries require regular maintenance
+  * FLA batteries require regular maintenance ("watering")
-  * FLA batteries have relatively high internal resistance and so cannot dump a bunch of power all at once.  This means huge banks of FLA to meet demanded current.
+  * FLA batteries have relatively high internal resistance and so cannot dump massive current on demand.  This means //huge// banks of FLA to meet big current demands.
   * When sitting still for long periods FLA electrolyte can stratify (separate into layers with different acidic strength).  This affects both performance and longevity as plates are damaged by areas of concentrate acid.((one of the purposes of the Equalization stage is to use outgassing to stir up the electrolyte)) In mobile installs like vans stratification is much less of an issue.
-AGM addressed all these issues and became the standard for backup-power banks.
+AGM addressed all these issues and became the standard for backup-power banks.  This is why telcos have lots of AGM to surplus out -- the base of cell towers contain AGM banks for backup, and they are rotated out on a schedule.
+Note that sitting on shore power indefinitely then dumping power on demand is the opposite of deep cycle use.
 ===== why do people use AGM in vans? =====
@@ Line 20: / Line 21: @@
   * because everybody else does, or did until LiFePO4 became the hot new trend
-  * fear of maintenance or ventilation
+  * concern about maintenance or ventilation
 ===== what does it take to keep them healthy? =====
@@ Line 26: / Line 27: @@
 The dark side of AGM's ability to discharge and bulk charge at higher rates is
-  - AGM //requires// more current during [[electrical:12v:charging#bulk_stage|Bulk charging]].  Typical minimum charge rates for AGM are [[electrical:12v:battery_capacity|0.15C to 0.2C]].  Some premium AGM require a minimum of 0.5C, or 50A per 100Ah of capacity.
+  - AGM //requires// more current during [[electrical:12v:charging#bulk_stage|Bulk charging]].  Typical minimum charge rates for AGM are [[electrical:12v:battery_capacity|0.15C to 0.2C]].  Some premium AGM require a minimum of 0.5C, or 50A per 100Ah of capacity. Failure to provide sufficient current regularly leads to a "walk-down effect" where the AGM underperforms until it receives a good kick in the pants.
-  - Higher-current bulk charging means shorter Bulk duration and therefore extended [[electrical:12v:charging#absorption_stage|Absorption duration]]
+  - Higher-current bulk charging means shorter Bulk duration and therefore extended [[electrical:12v:charging#absorption_stage|Absorption duration]].  Vandwellers struggle to provide adequate normal  Absorption duration, and completing an //extended// duration is even less likely.
+The easiest way to provide AGM with what it needs is to fully charge daily,  [[electrical:12v:alt_and_solar|combining]]
+  * alternator charging for Big Current in Bulk Stage
+  * solar charging for sufficient duration in Absorption stage

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