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electrical:depth_of_discharge [2020/03/09 15:36]
frater_secessus [SoC by voltage] 		electrical:depth_of_discharge [2020/06/23 10:55]
frater_secessus
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-====== Depth of discharge / State of Charge ======+===== Depth of discharge / State of Charge =====
  
-{{ http://popupbackpacker.com/wp-content/uploads/2013/12/State-of-Charge-Chart-Trojan.jpg?200|}}//Depth-of-discharge (DoD or DOD)// refers to how low a deep cycle battery is taken before recharging.  DoD is the inverse of //State of Charge (SoC)//.  Example:  a battery at 30% DoD is at 70% SoC.+{{ http://popupbackpacker.com/wp-content/uploads/2013/12/State-of-Charge-Chart-Trojan.jpg?200|}}//Depth-of-discharge (DoD or DOD)// refers to how low a deep cycle battery is taken between [[electrical:12v:charging|full charges]].  DoD is the inverse of //State of Charge (SoC)//.  Example:  a battery at 30% DoD is at 70% SoC.
  
 For solar powered systems the greatest DoD (and therefore lowest SoC) will be in early morning just before the panels start creating power again. For solar powered systems the greatest DoD (and therefore lowest SoC) will be in early morning just before the panels start creating power again.
  
 DoD has a **significant impact on longevity of deep cycle batteries**.  For this reason [[electrical:inverter|Inverters]] and other high-load devices may have a [[electrical:12v:lvd|low voltage cutoff]]. DoD has a **significant impact on longevity of deep cycle batteries**.  For this reason [[electrical:inverter|Inverters]] and other high-load devices may have a [[electrical:12v:lvd|low voltage cutoff]].
 +===== effect of SoC on battery life =====
 +
 +How deeply one regularly discharges lead-chemistry batteries will have a **direct effect on how long the battery bank will last**.((Banks are typically replaced when they have lost 20% of their capacity))
 +
  
 The **most common discharge limit for deep cycle batteries is 50% DoD**.  This gives a good balance between usability and longevity.  The **lowest cost per Ah** occurs around 30% DoD although this requires buying, installing, and moving //dead lead// or unusable battery capacity.((20% DoD is the limit at which manufacturers rate their battery's cycles.))   The **most common discharge limit for deep cycle batteries is 50% DoD**.  This gives a good balance between usability and longevity.  The **lowest cost per Ah** occurs around 30% DoD although this requires buying, installing, and moving //dead lead// or unusable battery capacity.((20% DoD is the limit at which manufacturers rate their battery's cycles.))  
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   * lowest cost per Ah happens at 30% DoD   * lowest cost per Ah happens at 30% DoD
   * longest life happens at 20% DoD   * longest life happens at 20% DoD
-  * least battery weight happens at 80%+  * least battery weight happens at 80% DoD
 so make your DoD decision based on what is most important to you. so make your DoD decision based on what is most important to you.
 +
 | |  **T105 Ah**| |  **Cost**|  **weight per set**|  **Target Ah**| | | | | |  **T105 Ah**| |  **Cost**|  **weight per set**|  **Target Ah**| | | |
 | |  225| |  $260.00|  124|  175| | | | | |  225| |  $260.00|  124|  175| | | |
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-===== SoC by amps =====+===== estimatating SoC ===== 
 + 
 +==== SoC by specific gravity ==== 
 + 
 +> "The truest measure of a [lead chemistry] battery's state of charge is the specific gravity of the battery acid." -- Rolls battery.((http://support.rollsbattery.com/support/solutions/articles/428-state-of-charge-charging-flooded-lead-acid-batteries)) 
 + 
 +Only flooded-type batteries are practical for SoC assessment by SG of the electrolyte.  Needed for this operation:  
 + 
 +  * temperature of the battery 
 +  * SG chart from the battery manufacuturer 
 +  * [[https://amzn.to/3dOHGEU|battery SG tester (hydrometer)]] 
 + 
 + 
 + 
 +==== SoC by amps ====
  
 A [[electrical:12v:battery_monitor|battery monitor]], usually a amp/coulumb counter with a shunt, will measure the current going to/from the battery.  It will often show real-time current flow and a state of charge percentage.  It may also show voltage (see below). A [[electrical:12v:battery_monitor|battery monitor]], usually a amp/coulumb counter with a shunt, will measure the current going to/from the battery.  It will often show real-time current flow and a state of charge percentage.  It may also show voltage (see below).
  
 +Note that deep cycle battery [[electrical:12v:battery_capacity|capacities]] are given at the "20 hour rate", roughly depleting the battery over the course of a day/night cycle. Heavier loads will cause apparent capacity to decrease.  Lithium is much less susceptible and tends to deliver more predictable capacity. 
  
  
  
-===== SoC by voltage =====+ 
 +==== SoC by voltage ====
  
 100% SoC (~12.7v) is measured [[electrical:12v:charging|after the bank has been fully charged]] and then rested. It is measured "on the way down";  measuring "on the way up" while charging will lead to false confidence and leaving the battery [[electrical:12v:psoc|less than fully charged]]. 100% SoC (~12.7v) is measured [[electrical:12v:charging|after the bank has been fully charged]] and then rested. It is measured "on the way down";  measuring "on the way up" while charging will lead to false confidence and leaving the battery [[electrical:12v:psoc|less than fully charged]].
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   * constant light loads with measured >=12.2v   * constant light loads with measured >=12.2v
   * intermittent heavier loads that leave the system with measured >=12.2v when that load is removed   * intermittent heavier loads that leave the system with measured >=12.2v when that load is removed
 +
 +
 +
 ===== partial state of charge ===== ===== partial state of charge =====
 This section [[electrical:12v:psoc|has moved]]. This section [[electrical:12v:psoc|has moved]].
  
electrical/depth_of_discharge.txt · Last modified: 2023/08/17 21:36 by frater_secessus

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