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electrical:solar:shallow_cycling [2020/01/14 15:49]
frater_secessus [effect on starter battery]
electrical:solar:shallow_cycling [2020/07/08 15:48]
frater_secessus [single voltage charging]
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 Instead of deep-cycling, the starter battery is //non-cycled//((never discharged below 100% state of charge)) as described below.  It can also be [[electrical:solar:shallow_cycling#shallow-cycling|shallow-cycled]].((discharged to 90% state of charge)) Instead of deep-cycling, the starter battery is //non-cycled//((never discharged below 100% state of charge)) as described below.  It can also be [[electrical:solar:shallow_cycling#shallow-cycling|shallow-cycled]].((discharged to 90% state of charge))
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 ==== how it works ==== ==== how it works ====
  
-  - a simple [[electrical:solar:charge_controller#shunt|shunt charge controller]] holds the battery at a mild Absorption voltage (14.0, - 14.2v) when charging, just below the significant gassing point+  - a simple [[electrical:solar:charge_controller#shunt|shunt charge controller]] holds the battery at a mild Absorption voltage (14.0, - 14.2v, see notes [[electrical:solar:shallow_cycling#charging_voltages_and_starter_batteries|below]]) when charging, just below the significant gassing point
   - the controller's LOAD output disconnects (LVD) at 100% SoC (~12.7v)   - the controller's LOAD output disconnects (LVD) at 100% SoC (~12.7v)
   - the controller's LOAD output //re//connects (LVR) at ~13.0v);  see discussion below   - the controller's LOAD output //re//connects (LVR) at ~13.0v);  see discussion below
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 Anecdote:  TreborEnglish runs his 75A flooded 12v wally world deep cycle to 87% SoC regularly and it has lasted 3 years as of this writing.  He reports it requires 20-30ml of water/month.((https://www.reddit.com/r/vandwellers/comments/enwq70/best_car_battery_for_van_life/fe670is/)) Anecdote:  TreborEnglish runs his 75A flooded 12v wally world deep cycle to 87% SoC regularly and it has lasted 3 years as of this writing.  He reports it requires 20-30ml of water/month.((https://www.reddit.com/r/vandwellers/comments/enwq70/best_car_battery_for_van_life/fe670is/))
  
-==== sample build ====+===== sample build =====
  
-  * 100w poly((for least expensive and best performance with [[electrical:solar:shunt_tweaking|shunt]]/[[electrical:solar:pwm_tweaking|pwm [[electrical:solar:charge_controller|controllers]]]])) panel on the roof, either a rack-mounted framed panel or a flex panel adhered to the surface.+Total cost, ~$140. 
 + 
 + 
 +  * 100w poly((for least expensive and best performance with [[electrical:solar:shunt_tweaking|shunt]]/[[electrical:solar:pwm_tweaking|pwm [[electrical:solar:charge_controller|controllers]]]])) panel on the roof, either a [[https://amzn.to/2snWQOL|rack-mounted framed panel]] that fits rack dimensions or a [[https://amzn.to/30rmAGD|flex panel]] adhered to the surface.
   * [[https://amzn.to/2ToGWyX|cable gland]] for getting wires through roof   * [[https://amzn.to/2ToGWyX|cable gland]] for getting wires through roof
-  * panel wires runs down the vehicle A-pillar inside the passenger area -- can be on driver or passenger side depending on where starter battery is located +  * panel wires runs down the vehicle A-pillar inside the passenger area((can be on driver or passenger side depending on where starter battery is located)) and into the PANEL terminals of  [[electrical:solar:shunt_tweaking|$10 shunt]] solar [[electrical:solar:charge_controller|charge controller]] mounted in the footwell or elsewhere 
-  * wires run to a [[electrical:solar:shunt_tweaking|$10 shunt]] solar [[electrical:solar:charge_controller|charge controller]] +  * [[https://amzn.to/2RhbHmD|wire]] run from controller's BATTERY terminals to the starter battery. 
-  * controller's BATTERY wires run from the controller to the starter battery. +  * wire run from  controller's LOAD terminals to [[https://amzn.to/3adk9vJ|12v/usb outlet]], power bus, etc  
-  * controller's LOAD wires run to outlet, power bus, etc + 
 + 
 +===== charging voltages and starter batteries ===== 
 + 
 + 
 +The chemistry of starter and "hybrid" ("marine") batteries is somewhat different than deep cycle batteries.  Speciically, starter batteries typically have calcium added to the positive grid to minimize self-discharge and outgassing.   
 + 
 +Problem:  calcium-enhanced grids are more susceptible to "positive grid corrosion" from sustained higher voltages.   
 + 
 +The question is this:  **what voltage can starter batteries be held at without damage**?   One answer might be be "alternator voltage" since that's already happening when we drive vehicles, and they are not damaged by long journeys.  
 + 
 +==== staged charging ==== 
 + 
 +CTEK's starter battery charger designed to be left on charges thusly:((https://www.ctek.com/storage/9E4D59B2526B4C3C54C61873C881CAACFC4C93F306DE1C8A2788E26EA6E506DA/f9b26d5eaeeb4787a51e5fc933ae1eae/pdf/media/687dd00827b44e44afee8695c5d0efab/MXS_3.8-manual-low-UK-EN.pdf)) 
 + 
 +  * 14.4v Absorption 
 +  * 13.6v Float  
 + 
 +So a charge controller with that configuration should be gentle enough on the battery. 
 + 
 + 
 +==== single voltage charging ==== 
 + 
 +This is the tricky part.  Shunts (or controllers set with [[electrical:12v:eternal_absorption|Vabs == Vfloat]]) have one charging voltage.  What should we use? 
 + 
 +  * folks who shallow cycle might charge to 14.4v to help counteract sulfation from overnight cycling. 
 +  * folks who non-cycle might charge to 13.6v as if the battery is simply being maintained.  This leaves some power on the table (~8.5%) for non-MPPT controllers but may be easier on the battery. 
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electrical/solar/shallow_cycling.txt · Last modified: 2023/04/08 13:41 by frater_secessus