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--- electrical:solar:nonessential [2020/01/13 11:20]
frater_secessus [how much surplus current is there?]
+++ electrical:solar:nonessential [2020/01/13 11:22]
frater_secessus [how much surplus current is there?]
@@ Line 12: / Line 12: @@
 It is common for Lead-Acid batteries to consume C/100 or C/200 amps to Float, meaning that **during Float** you will have **at least 99% your panels' output**((under present conditions)) **available for loads**.((normal + opportunity))
-**During Absorption** the charge current is tapering down as the battery accepts less;  the more it tapers down the more is available for loads.((agaom. normal + opportunity))  At the very beginning of Absorption ~0% of "bonus" output is available.  At the very end of Absorption 99%+ is available.  Mid-way through Absorption((judging by current not time)) ~49% of the panels' output is available for loads.
+**During Absorption** the charge current is tapering down as the battery accepts less;  the more it tapers down the more is available for loads.((agaom. normal + opportunity))  At the very beginning of Absorption ~0% of "bonus" output is available.  At the very end of Absorption 99%+ is available.  Mid-way through Absorption((judging by current not time)) ~49% of the panels' output is available for loads. See the image at the top of the page for an example of how current demand drops in Absorption.
 There will generally be more "surplus" power available when using MPPT charge controllers v. PWM,((http://forum.solar-electric.com/discussion/comment/372165#Comment_372165))((http://forum.solar-electric.com/discussion/comment/250746#Comment_250746)) though the difference is less dramatic during periods one would run opportunity loads (see [[electrical:solar:nonessential#when_to_run_opportunity_loads|below]]).  Siphoning off power can actually **help PWM controllers run cooler** by reducing the ON-OFF switching activity that generates heat.
@@ Line 21: / Line 21: @@
 Opportunity loads should not be applied during [[electrical:12v:charging|Bulk stage]] since Bulk, by definition, means the battery is taking all the available current.((assuming no charging limit has been configured in the [[electrical:solar:charge_controller|charge controller]]))
-For lead-acid batteries the loads are best applied in Float stage, or once past the beginning of Absorption.
-At the start of Absorption the controller still needs near-Bulk levels of current for charging.  At the end it needs almost no current.  **Halfway through Absorption about half of the system's peak power will be available for loads.**  See the image at the top of the page for an example of how current demand drops in Absorption.
 For [[electrical:12v:deep_cycle_battery#lithium_chemistries|LiFePO4]] set the LVD to Vfloat; there is no actual Absorption stage _per se_ in fractional-C charging. We use these setpoints only because our traditional lead-acid controllers work that way.

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