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--- electrical:solar:nonessential [2020/07/08 13:13]
frater_secessus [diversion controller]
+++ electrical:solar:nonessential [2020/07/08 14:58]
frater_secessus [LVD + timer - eternal Absorption]
@@ Line 26: / Line 26: @@
 ===== timing opportunity loads =====
+The trickiest part of running opportunity loads is running them at the right time so battery charging is not affected.
+==== manual model ====
 You can start the loads **manually** (ie, start using the power when you have extra).  This is error-prone but is free and requires no equipment (except your own memory).
-The most precise way to do it **automatically** is to use a charge controller that turns on the LOAD output only when the batteries are in Float stage.  Charge controllers with this feature tend to be expensive, and tend to run in either solar or dump load mode.  E.g. when dump load is active the batteries are not longer being maintained. This may be preferable with lithium or other chemistries that do not require multistage charging.
+==== charge controller ====
+The most precise way to do it **automatically** is to use a charge controller that can act as a diversion controller.  Charge controllers with this feature tend to be expensive, and tend to run in either solar **or** dump load mode.  This may be preferable with lithium or other chemistries that do not require multistage charging.
+Read the documentation and ask their techs questions before taking this $$$ approach.
+Related:
+  * you can also build a Pi or similar that talks to the controller over its communication port/protocol and checks when the controller is in Float, and then triggers the diversion.
+  * [[https://www.youtube.com/results?search_query=AC7391|some hobbyists are using AC7391 controllers]] to directly run dump loads w/out battery charging. Not necessarily a solution for vandwellers but may help our thinking.
-You can also build a Pi or similar that talks to the controller over its communication port/protocol and checks when the controller is in Float.
 ==== diversion controller ====
@@ Line 67: / Line 83: @@
 ==== LVD + timer - eternal Absorption ====
-This setup avoids timer juggling/estimation and does not affect Absorption charging.
+This setup avoids timer juggling/estimation and does not affect Absorption charging.The downside is the opportunity circuit engages much later.
   - [[electrical:12v:eternal_absorption|set Vfloat to Vabs]]
@@ Line 73: / Line 89: @@
   - set the LVD to just under Vabs, set the timer to the Absorption duration
+Similar to the above, this setup looks like: [LVD or controller LOAD output] –> timer –> relay –> load
 ===== uses for opportunity loads =====
+For best results the opportunity load should be sized to the excess power.  Otherwise the system could go into dump/recharge cycling.
   * heating water
   * [[hvac:dehumidifier|dehumidification]]

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