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--- electrical:solar:status [2023/08/09 13:54]
frater_secessus [transitioning to float]
+++ electrical:solar:status [2024/01/14 15:32] (current)
frater_secessus [setups with no float]
@@ Line 33: / Line 33: @@
 ===== first collect a few numbers =====
 To tell at a glance what your system is doing you need to find a couple pieces of info about your system.  You will only have to look them up once;  it might be worthwhile to write them down on a sticky note near your solar gear.
+{{ https://www.researchgate.net/profile/Kanaga-Gnana/publication/237049790/figure/fig3/AS:299465748566018@1448409606696/Characteristic-Curve-of-The-Solar-Panel.png?125}}
+==== panel specs ====
+The [[electrical:solar:panels#specifications|specs]] we are interested in are:
+  * **Vmp**, the voltage at which the panel makes max power under laboratory conditions((likely lower in reality))
+  * **Voc**, the highest voltage the panel will put out under normal cirumstances.  At Voc the panel produces no current and therefore no power (Voc x 0A = 0W)
+  * when in use, **Vpanel** is the panel voltage reported by the controller.  PWM controllers might not report this value.
+On the curve pictured at the right Vmp is at the peak of the red voltage line, and Voc is on the far right where output crashes to 0W.
+==== controller ====
   * **Vabs** - the charge controller's Absorption [[electrical:solar:charge_controller_setpoints|setpoint]], hopefully tweaked to your battery manufacturer's [[electrical:12v:charging|charging]] recommendation.  Note:  EpEver and Renogy controllers often refer to Absorption as //Boost//.
@@ Line 107: / Line 124: @@
 ==== setups with no float ====
-Configurations with no float ("charge and stop", found on some Lithium profiles) will stop charging then fall all the way to the reBulk/reBoost setpoint.  At that point they begin charging again.
+Configurations with no float ("charge and stop", found on some Lithium profiles) will
+  - charge to the Absorption ("boost") setpoint((with or without some amount of Absorption duration))
+  - **stop charging**
+  - until voltage falls to the rebulk ("reboost", "boost return voltage") setpoint
+  - repeat
+The fall to reBulk looks like the transition to Vfloat [[electrical:solar:status#transitioning_to_float|described above]]. In both cases the controller makes no (or practically no) power until the lower setpoint is reached.
+A constant cycling 14.4v->13.2v->14.4v might seem extreme but in practice there is little actual cycling occurring.  A fully-charged 4S LFP with no loads will rest somewhere around **13.6v**. So for actual SoC changes we are talking about the difference between 13.6v and 13.2v.  With significant loads applied 13.2v observed could mean SoC as high as 90% and with trivial loads as low as 70%.((with trivial loads there might be only 1 cycle a day since voltage would not fall to reBoost))  In normal use the real cycling might be 100%->85%-100% and the solar is helping carry the loads during charging periods.
+=== Renogy confusion ===
+By default Renogy Li profiles work this way, and cause much concern for Renogy users who have not read their manuals and/or who are not familiar with how solar charge controllers / chargers work. [The required information is present [[https://www.renogy.com/support/downloads|in the manuals]] but Renogy really should spell it out for first-timers. -- secessus]
+  * **Rover series** - the table on page 37 of [[https://www.renogy.com/content/RNG-CTRL-RVR40/RVR203040-Manual.pdf|the manual]] shows there is no boost duration and no float in the Li profile.  The "boost return voltage" field shows **13.2v**.
+  * **DC-DC/MPPT combo charger** - the table on page 2 of [[https://www.renogy.com/content/RBC3050D1S-G1/RBC3050D1S-Manual.pdf|the manual]] shows there is no boost duration and no float in the Li profile.  The "boost return voltage" field shows **13.2v**.
+  * **DC-DC charger** (20A/40A/60A)
+    * page 18 says "lithium batteries will only have an absorption charge and no float charge"
+    * there is no setting for Float charge, as shown in the table on page 17 of [[https://www.renogy.com/content/RNG-DCC1212-60-BC/DCC1212-204060-Manual.pdf|the manual]] and it says "for lithium... there will not be a float voltage"
+    * page 18 says that Float is for lead only
+    * the manual does not state the 13.2v boost return setpoint [an egregious error - secessus]
+Users uncomfortable with this behavior can set up the USER profile to meet their needs, including defining [[electrical:12v:drop-in_lifepo4#mythyou_shouldn_t_float_lithium|a quasi-Float setpoint]].((low temp charging cutoff, when available, may only be available in canned Li profiles))
-The fall to reBulk looks like the transition to Vfloat described above. In both cases the controller makes no (or practically no) power until the lower setpoint is reached.
 ==== in float ====

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