RVwiki for vanfolk and others who live in vehicles

User Tools

Site Tools

Trace:
electrical:12v:alt_and_solar

Differences

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

Link to this comparison view

Both sides previous revision Previous revision
Next revision 		Previous revision
electrical:12v:alt_and_solar [2023/05/24 21:42]
frater_secessus [how solar helps] 		electrical:12v:alt_and_solar [2025/08/23 22:14] (current)
frater_secessus [putting it all together]
Line 1: Line 1:
-Note:  although this page was written with alternator-augmented solar charging in mind, the general principles also apply to solar+[[electrical:shore_power|shore power charging]] and solar+[[electrical:generator|generator]] charging. +Note:  although this page was written with alternator-augmented solar charging in mind, the general principles also apply to solar+[[electrical:shore_power|shore power charging]] and solar+[[electrical:generator|generator]] charging. Also see [[electrical:12v:power_mix|Deciding on a Power Mix]]. 
 + 
 + 
 +> Solar and DC-DC alternator charging are going to be the best practices for maintaining charge in one's battery bank. It only requires a little math, a little discipline to stick with the math, and the right expectations about solar intake.  -- CMDR_Schrodinger((https://www.reddit.com/r/vandwellers/comments/15z8eh6/energy_management_during_trips/jxfv03f/))
  
  
-[[lifestyle:words_of_wisdom|Words of wisdom]]: "Bulk charging requires //current//. Absorption requires //relatively high voltage// and //time at that voltage//." - secessus 
  
 ====== Augmented solar charging ====== ====== Augmented solar charging ======
Line 33: Line 35:
 Alternator charging is extremely powerful and cheap compared to typical solar installs.  It works best when solar works worst:  when the batteries are deeply discharged in the morning.  The sun is weak then but the bank needs a large supply of current (early [[electrical:12v:charging#bulk_stage|Bulk charging]]).   Alternator charging is extremely powerful and cheap compared to typical solar installs.  It works best when solar works worst:  when the batteries are deeply discharged in the morning.  The sun is weak then but the bank needs a large supply of current (early [[electrical:12v:charging#bulk_stage|Bulk charging]]).  
  
-[[electrical:solar:charge_controller#pwm|PWM]] controllers are especially hamstrung in this scenario;  since they run the panels at battery voltage (Vbatt) they produce the least power exactly when the most power is required.  By the time alternator voltage (Valt) is reached PWM controllers are able to produce meaningful power.+[[electrical:solar:charge_controller#pwm|PWM]] controllers are [[electrical:solar:pwm_tweaking#pwm_s_achilles_heel|somewhat hamstrung in this scenario]];  because they run the panels ~at battery voltage((for the purposes of this discussion)) (Vbatt) they produce the least power exactly when the most power is required.  Pushing up bank voltage with the alt helps the PWM make more power.  
  
 Alt charging shovels current into the bank until Valt is reached, at which point it begins to taper off.  Solar can take it from there.  A good metaphor might be a two-stage rocket:  the alternator does the heavy lift getting the rocket off the ground then the solar charging takes care of the high altitude, high speed duties.  Alt charging shovels current into the bank until Valt is reached, at which point it begins to taper off.  Solar can take it from there.  A good metaphor might be a two-stage rocket:  the alternator does the heavy lift getting the rocket off the ground then the solar charging takes care of the high altitude, high speed duties. 
Line 39: Line 41:
 > Use a generator or alternator to get to 85% SOC or so early in the AM, then let Solar spend all day polishing off the last 15% because that takes time more than amps. - a64pilot((https://www.cruisersforum.com/forums/f14/time-it-takes-to-fully-charge-batteries-238875-9.html#post3223983)) > Use a generator or alternator to get to 85% SOC or so early in the AM, then let Solar spend all day polishing off the last 15% because that takes time more than amps. - a64pilot((https://www.cruisersforum.com/forums/f14/time-it-takes-to-fully-charge-batteries-238875-9.html#post3223983))
  
 +
 +The alternator can help meet [[electrical:12v:charging#charging_current|lead bank minimum charging current requirements]].  
 ===== optimal alternator contribution ===== ===== optimal alternator contribution =====
  
-Broadly speaking, //alternator charging is most effective in the morning// and //solar charging is most effective later in the day//.  +Note:  this section talks about alternator contribution but also applies to generators.  
 + 
 +Broadly speaking, //alternator charging are most effective in the morning// and //solar charging is most effective at local solar noon//.  This pattern is most evident when using isolators/relays and/or lead chemistry batteries, and less evident when using [[electrical:12v:b2b|DC-DC chargers]] and/or lithium chemistries.
  
 There are several factors in play here.   There are several factors in play here.  
Line 79: Line 85:
 ==== putting it all together ==== ==== putting it all together ====
  
-Alternator((or generator)) charging is most helpful/efficient((Ah replaced for a  given amount of engine runtime)) in the morning when the bank voltage and state of charge are lowest.  This may mean shifting driving errands to mornings or rainy days.+Alternator (or generator) charging is most helpful/efficient((Ah replaced for a  given amount of engine runtime)) in the morning when the bank voltage and state of charge are lowest.  This may mean shifting driving errands to mornings or rainy days.
  
  
Line 89: Line 95:
  
   - the Li voltage curve is very flat in the middle, so the voltage delta will be stable through the "middle 80%"   - the Li voltage curve is very flat in the middle, so the voltage delta will be stable through the "middle 80%"
-  - for average users, Li will not have an Absorption stage in the lead-chemistry sense.((advanced users may find [[electrical:12v:electrical:12v:drop-in_lifepo4#mythlithium_doesn_t_need_absorption|exceptions]] to this general statement))+  - for average users, Li will not have an Absorption stage in the lead-chemistry sense.((advanced users may find [[electrical:12v:drop-in_lifepo4#mythlithium_doesn_t_need_absorption|exceptions]] to this general statement))
   - Lithium is often charged with DC-DC, which charges at the ~same voltage as solar   - Lithium is often charged with DC-DC, which charges at the ~same voltage as solar
  
electrical/12v/alt_and_solar.1684964544.txt.gz · Last modified: 2023/05/24 21:42 by frater_secessus

Page Tools

affilliate disclosure | the RVwiki runs on a virtual server from NetCup

Except where otherwise noted, content on this wiki is licensed under the following license: CC Attribution-Noncommercial-Share Alike 4.0 International
CC Attribution-Noncommercial-Share Alike 4.0 International Donate Powered by PHP Valid HTML5 Valid CSS Driven by DokuWiki