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electrical:solar:shallow_cycling [2020/01/14 12:49]
frater_secessus [sample build]
electrical:solar:shallow_cycling [2020/07/08 12:51] (current)
frater_secessus [how it works]
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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) 
-  - power is //only// taken from the controller'​s LOAD output;((or from a circuit control by a relay on the LOAD output)) this ensures the starter battery is never discharged below [[electrical:​12v:​lvd|the intended setpoint]]+  - power is //only// taken from the controller'​s LOAD output;((or from a circuit control by a relay on the LOAD output)) this ensures the starter battery is never discharged below [[electrical:​12v:​lvd|the intended setpoint]].  Since the load is disconnected below 12.7v the battery cannot be run down by loads. ​
  
 === Low Voltage Reconnect (LVR) setpoint === === Low Voltage Reconnect (LVR) setpoint ===
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 ===== 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.1579034988.txt.gz · Last modified: 2020/01/14 12:49 by frater_secessus