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--- electrical:12v:alternator [2020/05/24 12:07]
frater_secessus [gotchas]
+++ electrical:12v:alternator [2020/06/23 12:04]
frater_secessus [diode-based isolator]
@@ Line 46: / Line 46: @@
 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?125 }}]]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 ====
@@ Line 62: / Line 74: @@
   - 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.
-[[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:  [[jump|Victron Argo 200A FET Battery Isolator]]
 ==== manual switch ====
@@ Line 135: / Line 151: @@
 **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)).
-==== wiring ====
+===== wiring =====
 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 159: @@
 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:

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