User Tools

Site Tools


electrical:12v:alternator

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
Next revision Both sides next revision
electrical:12v:alternator [2020/05/24 12:07]
frater_secessus [gotchas]
electrical:12v:alternator [2020/10/11 11:46]
frater_secessus [gotchas]
Line 22: Line 22:
 Alternator charging is generally only practical for the [[electrical:12v:charging|bulk charge stage]] due to relatively low voltage output and the [[electrical:12v:charging|long time periods required for absorption]].(([[electrical:12v:b2b|DC-DC chargers]] can help with the voltage))  It is unlikely to get the house battery completely charged unless one is driving significant distances. This can have an impact on [[electrical:batterycide|battery longevity]].  If one drives often [[electrical:12v:alt_and_solar|a combination of the alternator doing bulk charging and a small solar doing the rest]] is good match. Alternator charging is generally only practical for the [[electrical:12v:charging|bulk charge stage]] due to relatively low voltage output and the [[electrical:12v:charging|long time periods required for absorption]].(([[electrical:12v:b2b|DC-DC chargers]] can help with the voltage))  It is unlikely to get the house battery completely charged unless one is driving significant distances. This can have an impact on [[electrical:batterycide|battery longevity]].  If one drives often [[electrical:12v:alt_and_solar|a combination of the alternator doing bulk charging and a small solar doing the rest]] is good match.
  
-See [[electrical:12v:mandatory solar|Is Solar Mandatory?]] for ideas on how to charge primarly by alternator.+Vehicles with //smart// (variable voltage) alternators may not be suitable for charging with normal isolators.((https://www.redarc.com.au/how-do-i-know-if-i-have-a-variable-voltage-smart-alternator))  See [[electrical:12v:alternator#smart_alternators|below]]. 
 + 
 +See [[electrical:12v:mandatory solar|Is Solar Mandatory?]] for ideas on how to charge primarily by alternator.
  
  
Line 37: Line 39:
 Anecdotally the problem appears to be worsened with **excessive idling**, although this may be a subset of situations where "the engine doesn’t run long enough or hard enough to get hot enough to burn any of the carbon off."((https://automotiverepairphoenix.com/ask-car-guy-can-carbon-build-impact-engine/)) Anecdotally the problem appears to be worsened with **excessive idling**, although this may be a subset of situations where "the engine doesn’t run long enough or hard enough to get hot enough to burn any of the carbon off."((https://automotiverepairphoenix.com/ask-car-guy-can-carbon-build-impact-engine/))
  
 +===== smart alternators =====
  
 +Traditional alternators typically try to hold a set voltage.  //Smart alternators// talk to the vehicle's ECU (compuuter) vary output voltage depending on present conditions.  It might unload the alternator during heavy acceleration to reduce parasitic losses, or run the alternator at high voltage just after starting to speed up the recovery of used energy.((https://www.redarc.com.au/alternator-vs-fixed-alternator))
 +
 +The use of plain isolators with smart alternators may result in the rapid cycling of the isolator's circuit (with voltage sensing types) or the discharge of the house battery into the starter battery (solendoid type).
 +
 +[[electrical:12v:b2b|DC-DC chargers]] and/or isolators with an awareness of smart alternators may be required.
  
  
Line 46: Line 54:
  
 Power from the alternator is shared with the house battery using an isolator ("Split charge relay" / SCR) of some sort.  This allows the [[electrical:12v:intro|house battery]] to charge but does not allow the house battery to pull power from the starter battery. Power from the alternator is shared with the house battery using an isolator ("Split charge relay" / SCR) of some sort.  This allows the [[electrical:12v:intro|house battery]] to charge but does not allow the house battery to pull power from the starter battery.
 +
 +
 +
 +
 +
 +
  
 ==== constant-duty solenoid ==== ==== constant-duty solenoid ====
Line 62: Line 76:
   - DC-DC isolators (aka //[[electrical:12v:b2b|b2b]] isolators//) that boost alternator voltage to [[electrical:12v:charging|more appropriate levels for lead chemistries]] and can do multistage charging. These have [[electrical:12v:b2b|their own page]].   - DC-DC isolators (aka //[[electrical:12v:b2b|b2b]] isolators//) that boost alternator voltage to [[electrical:12v:charging|more appropriate levels for lead chemistries]] and can do multistage charging. These have [[electrical:12v:b2b|their own page]].
  
-==== diode-based isolator ====+==== solid state isolator:  diode-based ====
  
 Note:  this type of isolator is no longer common for our uses.  Note:  this type of isolator is no longer common for our uses. 
  
-[[http://amzn.to/2gVwmKw|Solid state isolators]] are electronic devices which use diodes to prevent depletion of the starter battery.  **Isolators are generally brick-shaped**.  Diode-based isolators have a **0.5v - 1v drop** between the alternator and house battery. This may be desirable if the house battery is a wants lower-voltage charging like [[electrical:12v:lifepo4_batteries_thread|LiFePO4]].  Some solid state isolaters use FETs and diodes in tandem to reduce voltage drop. \\ Note:  solid state relays can't combine batteries for self-jumpstarting.+[[http://amzn.to/2gVwmKw|These isolators]] are electronic devices which use diodes to prevent depletion of the starter battery.  **Isolators are generally brick-shaped**.  Diode-based isolators have a **0.5v - 1v drop** between the alternator and house battery. This may be desirable if the house battery is a wants lower-voltage charging like [[electrical:12v:lifepo4_batteries_thread|LiFePO4]].  Some solid state isolaters use FETs and diodes in tandem to reduce voltage drop. \\ Note:  solid state relays can't combine batteries for self-jumpstarting.
  
 +==== solid state isolator:  FET-based ====
  
 +This type of isolator is similar to the diode-based one above, except that FET components are used instead of diodes, preventing voltage drop.  
 +
 +Example:  [[https://amzn.to/2Cwjkln|Victron Argo 200A FET Battery Isolator]]
 ==== manual switch ==== ==== manual switch ====
  
 +[[https://amzn.to/2VaL8SG|{{https://m.media-amazon.com/images/I/81n-ap+0lPL._AC_UY218_.jpg?125 }}]]The simplest and least-featured isolator is a //manual switch//.
  
 A [[http://amzn.to/2gsDtNc|manual battery switch]] normally has 4 positions: A, B, A+B, and Off. A would be for the starter battery and used during starting. B would be used for house use when one is not driving. A+B could be used to combine both sets for starting or for charging while driving. This kind of setup is prone to user error. A manual switch has no current or voltage losses. A [[http://amzn.to/2gsDtNc|manual battery switch]] normally has 4 positions: A, B, A+B, and Off. A would be for the starter battery and used during starting. B would be used for house use when one is not driving. A+B could be used to combine both sets for starting or for charging while driving. This kind of setup is prone to user error. A manual switch has no current or voltage losses.
 +
 +==== misc ====
 +
 +[note from secessus:  "not sure what's inside these solid state isolators"]
 +
 +[[https://amzn.to/3fVuKh0|{{ https://m.media-amazon.com/images/I/51XoShK5uIL._AC_UY218_.jpg?125}}]]
 +The [[https://amzn.to/3fVuKh0|Magnum Energy ME-SBC]] is notable for some unusual features:
 +  * configurable connect/disconnect setpoints
 +  * ability to drive a solenoid, which allows for much greater current
 +
 +Xantrex makes [[https://amzn.to/3eKhkEc|a 15A Digital-Echo Charge isolator]]. 
 +
 +
 +
 +
 +
  
 ===== sizing an isolator ===== ===== sizing an isolator =====
Line 131: Line 166:
 ===== gotchas ===== ===== gotchas =====
  
-Alternator charging may bring some battery chemistries (like lithium) to **unsuitably high voltages**  A [[electrical:12v:hvd|high voltage disconnect]] can [[electrical:12v:alternator charging hvd|restrict alternator charging to lower voltages]].  [[electrical:12v:b2b|DC-DC chargers]] can also regulate voltage provided to the house battery+ 
 +Solar charging while the isolator circuit is closed (ie, batteries connectedcan pass higher-than-normal voltage to the chassis and starter battery See notes on HVD and DC-DC charging above.  
 + 
 +Voltage-sensing regulators can be [[http://bdp.mousetrap.net/index.php/2018/10/27/side-effect-of-solar-alternator-charging/|triggered or "held closed" by voltage from the solar-charged side]] in some scenarios  Address with HVD as above if desired
  
 **Idling the engine** to charge house batteries **can seriously overheat the alternator**.  It is usually cooled by wind from the vehicle's forward motion;  a fan may help cool the alternator. **Idling the engine** to charge house batteries **can seriously overheat the alternator**.  It is usually cooled by wind from the vehicle's forward motion;  a fan may help cool the alternator.
  
-In early morning when house battery voltage is lowest, a plain solenoid may unintentionally allow depleted batteries to pull down the starter battery.  Workarounds:  use a VSR, or start the vehicle immediately after inserting the key((ie, do not leave in the Accessory position which would drain the starter battery)).  +In early morning when house battery voltage is lowest, **a plain solenoid may unintentionally allow depleted batteries to pull down the starter battery**.  Workarounds:  use a VSR, or start the vehicle immediately after inserting the key((ie, do not leave in the Accessory position which would drain the starter battery)).   
 + 
 +Solar charging while the isolator circuit is closed may [[opinion:frater_secessus:alternatorSolarStall|"stall" at alternator voltage]]. 
 + 
 +Alternator charging may bring some battery chemistries (like bare lithium cells with no BMS) to **unsuitably high voltages**.   A [[electrical:12v:hvd|high voltage disconnect]] can [[electrical:12v:alternator charging hvd|restrict alternator charging to lower voltages]].  [[electrical:12v:b2b|DC-DC chargers]] can also regulate voltage provided to the house battery.  
  
-==== wiring ====+===== wiring =====
  
 2 gauge copper wire connecting the coach and house is recommended for most alternator charging installs.  SternWake recommends attaching at the alternator rather than the battery.((http://www.cheaprvliving.com/forums/Thread-Charge-house-batteries-with-DC?pid=110652#pid110652)) 2 gauge copper wire connecting the coach and house is recommended for most alternator charging installs.  SternWake recommends attaching at the alternator rather than the battery.((http://www.cheaprvliving.com/forums/Thread-Charge-house-batteries-with-DC?pid=110652#pid110652))
Line 143: Line 186:
 Note that you will only have to run the POS+ leg of wire to the house battery as the chassis ground is the other leg. Note that you will only have to run the POS+ leg of wire to the house battery as the chassis ground is the other leg.
  
-==== alternator hacks ===+===== alternator hacks =====
  
 There are ways to get the alternator to pump out more power: There are ways to get the alternator to pump out more power:
electrical/12v/alternator.txt · Last modified: 2024/03/15 12:27 by frater_secessus