Differences

This shows you the differences between two versions of the page.

--- electrical:solar:shallow_cycling [2018/03/02 09:44]
frater_secessus [how it works] relay
+++ electrical:solar:shallow_cycling [2020/07/08 15:51]
frater_secessus [how it works]
@@ Line 8: / Line 8: @@
 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))
 ===== non-cycling =====
-//Non-cycling// is the use of solar power only when the battery is fully charged.
+//Non-cycling// is the use of solar power only when the battery is fully charged.  The starter battery is even more fully charged than in normal vehicles.
 ==== how it works ====
-  - a simple [[electrical:solar:charge_controller#shunt_controller|shunt charge controller]] holds the battery at a mild Absorption voltage (14.0, - 14.2v) when charging, just below the 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 //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 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 ===
@@ Line 27: / Line 32: @@
 If **running larger loads** (fans, laptop chargers) the setpoint should be set higher (like 13.5v - 14.0v).  This is because the panel will be able to make more power closer to Vmp.  Consider the popular [[http://amzn.to/2you3Kj|Renogy 100w panel]] that puts out about 5.29A.  At the lower LVR the panel((under lab conditions)) will make **68.77W**.  At the higher LVRs the panel will make **71.42-74.06W**
-Note:  running a small MPPT [[electrical:solar:charge_controller|charge controller]] would make this immaterial, as the controller would run the panel at max power (Vmp) at 18.9v.
+Note:  running a small [[electrical:solar:charge_controller#mppt|MPPT]] [[electrical:solar:charge_controller|charge controller]] would make this immaterial, as the controller would run the panel at max power (Vmp) at 18.9v.
@@ Line 44: / Line 49: @@
 ===== shallow-cycling =====
-//Shallow-cycling// is a more aggressive approach, allowing for a bit of power after sundown.  It is most **suitable for starter batteries with removable cell caps**.
+//Shallow-cycling// is a more aggressive approach, allowing for more power in the daytime and some power for use after sundown.  It is most **suitable for starter batteries with removable cell caps**.
 The charging setpoint is set somewhat higher, ~14.4v.  This will result in minor outgassing and a bit more power (**76.18W** using the panel data above).  [[electrical:12v:charging#watering_batteries|Battery watering]] is mandatory.
@@ Line 50: / Line 55: @@
 Starter batteries are designed for about 15% depth of discharge((http://forum.solar-electric.com/discussion/comment/60412#Comment_60412)).  We can set the Low Voltage Disconnect (//Vlvd//) to 12.5-12.6v as a floor.  In a typical starter battery this could be 5Ah of power usable at night, enough to run an LED light for hours as well as run a small fan all night.  All device charging should happen in daylight when power is relatively plentiful.
-If the starter battery (when it eventually dies a natural death) were replaced with [[electrical:12v:deep_cycle_battery#chain_store_batteries|a 12v wally world marine battery]] one might be able to cycle to 25% DoD.  This would mean an Vlvd of ~12.4v and 8-9Ah of power at night.
+If the starter battery (when it eventually dies a natural death) were replaced with [[electrical:12v:deep_cycle_battery#chain_store_batteries|the heaviest 12v wally world marine battery]] that would fit one might be able to cycle to 25% DoD.  This would mean an Vlvd of ~12.4v and 8-9Ah of power at night.
 ===== effect on starter battery =====
@@ Line 68: / Line 73: @@
 > "most of the "defective" batteries returned to manufacturers during free replacement warranty periods are good"((https://www.batterystuff.com/kb/articles/battery-articles/how-do-batteries-die.html))
 ... A charging regime might even extend the perceived longevity of the starter battery.
+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 =====
+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
+  * 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 a  [[electrical:solar:shunt_tweaking|$10 shunt]] solar [[electrical:solar:charge_controller|charge controller]] mounted in the footwell or elsewhere
+  * [[https://amzn.to/2RhbHmD|wire]] run from controller's BATTERY terminals to the starter battery.
+  * wire run from  controller's LOAD terminals to [[https://amzn.to/3adk9vJ|12v/usb 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.

RV and vandwellers wiki

User Tools

Site Tools

Differences

Page Tools