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electrical:12v:alternator [2020/05/21 07:46]
frater_secessus [isolators]
electrical:12v:alternator [2020/06/23 08:58]
frater_secessus [isolators]
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 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.
 +
 +
 +==== manual switch ====
 +
 +[[https://​amzn.to/​2VaL8SG|{{https://​m.media-amazon.com/​images/​I/​81n-ap+0lPL._AC_UY218_.jpg }}]]The simplest and least-featured isolator is a //manual switch//.
 +
 +Pro:  very little to go wrong.
 +
 +Con:  must be operated manually and one must remember to do so. Leaving the switch in the combined position when not driving will drain both the house and starter battery.
 +
 +
 +
  
 ==== constant-duty solenoid ==== ==== constant-duty solenoid ====
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 ===== 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]].+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.  
 + 
 +**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 run the alternator 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 VSR, or start the vehicle immediately after inserting the key((ie, do not leave in the Accessory position which would drain the starter 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))
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 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: 2020/07/12 17:47 by frater_secessus