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--- electrical:depth_of_discharge [2023/08/18 01:26]
frater_secessus [knowing when SoC is 100% (fully charged)]
+++ electrical:depth_of_discharge [2023/08/18 01:36] (current)
frater_secessus [effect of DoD on lead battery life]
@@ Line 4: / Line 4: @@
 DoD is the inverse of //State of Charge (SoC)//.  Example:  a battery at 30% DoD is at 70% SoC.
-DoD has a **significant impact on longevity of lead deep cycle batteries**.((and, to a lesser degree, lithium batteries))  For this reason [[electrical:inverter|Inverters]] and other high-load devices may have a [[electrical:12v:lvd|low voltage cutoff]] to prevent going below a given SoC, typically 50%.
 Note: This information is primarily relevant to lead-chemistry batteries.  Lithium batteries have [[#lithium_soc|different DoD capabilities and lifecycles]].
@@ Line 34: / Line 32: @@
 Solar is typically a moderate (or "soft") charging source so the guidelines above are probably close enough to start from.  Alternator charging from [[electrical:12v:directcharginglfp|combiner]] or large [[electrical:12v:b2b|DC-DC]] may be high ("firm") enough for SoC estimates to be artificially high.
-So while we can say with confidence that a 100Ah Li battery charged at 20A to 14.0v will be ~100% SoC, the same battery charged to 14.0v at 80A might only be at 75% SoC.  The amp counter will probably help here during charging although even it can be thrown off.
+So while we can say with confidence that a 100Ah Li battery charged at 20A to 14.0v will be ~100% SoC, the same battery charged to 14.0v at 80A might only be at 75% SoC.  And it **could get damagingly overcharged** if charged to 14.0v very gently at something like 5A.((the BMS cannot detect this scenario))
+The amp counter will probably help here during charging although even it can be thrown off;  see the battery monitor article for more on this.
@@ Line 126: / Line 126: @@
 ===== effect of DoD on lead 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))
+DoD has a **significant impact on longevity of lead deep cycle batteries**.((and, to a lesser degree, lithium batteries))  For this reason [[electrical:inverter|Inverters]] and other high-load devices may have a [[electrical:12v:lvd|low voltage cutoff]] to prevent going below a given SoC, typically 50%.  Since this is judged by voltage it is am imperfect science.
-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.
 Based on the following data on the Trojan T-105:

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