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--- electrical:solar:status [2019/11/12 12:35]
frater_secessus [in absorption]
+++ electrical:solar:status [2020/08/29 22:47]
frater_secessus [in bulk]
@@ Line 69: / Line 69: @@
   * Vpanel == Vmp((although [[electrical:solar:output|temperature derating]] will cause Vmp to drop))
   * Vbatt climbing toward Vabs
-  * Current delivered to battery holds steady((assuming sunlight holds steady))
+  * charge delivered to battery holds steady((assuming sunlight holds steady))  Note:  in a lab environment with DC power supplies the current (measured in Amps) could stay steady as the battery approaches Vabs.((the charger would get more and more wattage from the wall socket))  When charging off-grid we are typically limited by charging wattage, say 300w from the alternator or panels.  At 12.1v you would see ~25A charging (300w/12.v = 24.79A) but at 14v you'd only see ~21.5A (300w/14v = 21.43A)
   * **Example:**  Panel voltage at Vmp == 17v, battery voltage 12.9v and rising, controller output steady at 4A.
@@ Line 94: / Line 94: @@
   * the controller may get warmer as current demand drops((percentage of time the PWM circuit is turned OFF increases))
   * **Example:**  Panel and battery voltage held at Vabs == 14.6v, controller output 2A and dropping
+==== transitioning to float ====
+When transitioning from Absorption to Float the voltage needs to drop about a volt.  The system will "free-fall" (make little or no power) to allow the voltage to fall.((with MPPT controllers you may see Vpanel go quite close to Voc))   The transition may take seconds or minutes, depending on how/if the system is loaded.
+  * Vbatt starts at Vabs
+  * power harvest is cut off or greatly curtailed
+  * vbatt drops to Vfloat
+  * when voltage reaches Vfloat the system will start making power to hold //that// setpoint.
 ==== in float ====
 **During Float with MPPT**
-  * Vpanel close to Voc
+  * Vpanel closer to Voc
   * Vbattery == Vfloat
   * controller output minimal((assuming no loads))
@@ Line 123: / Line 133: @@
   * If enough power is available no change will be observed but the controller may run cooler((as PWM switching reduces in frequency.))
   * If demand outstrips supply the Vbattery & Vpanel will drop((causing a bit of a "death spiral", as PWM produces less power as panel voltage drops))
-  * **Example**:  Upon adding load, the controller releases power it had been dissipating in the PWM circuit.  Current output spikes to meet load demand.((this is reflected in either battery charging amps or load amps depending on how the loads are wired))  Output is limited to whatever power the panel puts out at Vabs & Vfloat.((almost certainly less than what the panel could put out at Vmp))
+  * **Example**:  Upon adding load, the controller releases power it had been constricting (modulating the pulse width). Current output spikes to meet load demand.((this is reflected in either battery charging amps or load amps depending on how the loads are wired))  Output is limited to whatever power the panel puts out at Vabs & Vfloat.((almost certainly less than what the panel could put out at Vmp))

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