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--- electrical:12v:alternator [2024/04/26 16:58]
frater_secessus [alternator current rating]
+++ electrical:12v:alternator [2024/05/09 14:00] (current)
frater_secessus [isolator without a house battery]
@@ Line 113: / Line 113: @@
 See [[electrical:12v:alternator_details#heat|this sub-article]] on alternators and heat
+==== alternator current rating ====
+In general, vehicles with higher-rated alternators (150A, for example) will handle a given load better than vehicles with lower-rated alternators (60A, for example).  The rating in Amps will be listed on the window sticker, often on the alternator housing itself, or can be looked up using a VIN decoder for your automaker.
+see [[electrical:12v:alternator_details#current|this related article]] on assessing how much current you can safely take from the alternator
 ==== fuel consumption ====
@@ Line 648: / Line 656: @@
   - use [[electrical:12v:b2b|a DC-DC charger]] to get at least the correct charging voltage
   - if charging by relay only, use Crtical size wire to get the most voltage and current to the lead house battery
+==== triggering  ====
+The setup needs to be //triggered// (told when to start/stop) so that it isn't connected all the time.  There are two main methods:
+  - use of an ON/OFF 12v trigger signal ("D+", "IGN", "ACC").  When the 12v signal is present the charging circuit is operational.  Caveat:  in this kind of setup leaving the key in the ACC position without starting the engine can drain the starter battery.
+  - voltage-sensing - 12v is always being provided to the charger.  The batteries are connected when the chassis voltage is above a voltage setpoint (often ≥13.4v) and disconnected when the chassis side measures below  a setpoing (often ≤13.2v).
+In some cases both are combined for particular installs.  Ex.  smart alternators.
 ===== alternator hacks =====
@@ Line 699: / Line 719: @@
 ==== workaround: heavier wiring ====
-It's also possible to run a separate and heavier cable from the TV to the trailer;  this would minimize voltage sag.  If a plain isolator is used with heavier wiring the voltage will still be insufficient to fully charge lead batteries.
+It's also possible to run a separate and (much) heavier & more expensive cable/connector from the TV to the trailer;  this would minimize voltage sag.
-Heavier cabling + a DC-DC charger could provide correct voltage to the trailer battery.
 ===== isolator without a house battery =====
@@ Line 716: / Line 737: @@
-This setup would be:  starter battery -> isolator -> inverter -> 120vac devices
+This setup would be:  starter battery -> combiner((A $25-$40 VSR (often marketed as a smart battery isolator) might be easiest. Could go even cheaper with a regular relay but you'd have to hunt for a D+/IGN signal.))
+ -> inverter -> 120vac devices

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