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--- electrical:12v:alternator [2019/06/23 18:01]
frater_secessus [isolators]
+++ electrical:12v:alternator [2019/06/23 20:43]
frater_secessus [alternator hacks]
@@ Line 39: / Line 39: @@
 ===== sizing an isolator =====
-If an isolator is **oversized** it will cost more for no benefit and will self-consume extra energy to hold the combining circuit closed.((an electromagnet holds the parts of the active circuit together.  When power to the insolator input is cut the electromagnet can no longer hold the circuit closed.  The batteries are now isolated from each other.))  If an isolator is undersized (less common) it will not be able to carry enough current, overheat,  and electronic models may reset or shut down.
+If an isolator is **oversized** it will cost more for no benefit and will self-consume somewhat more energy to hold the combining circuit closed.((an electromagnet holds the parts of the active circuit together.  When power to the inolator input is cut the electromagnet can no longer hold the circuit closed.  The circuit is open and the batteries are isolated from each other.)) \\
+If an isolator is **undersized** (less common) it will not be able to carry enough current, resulting in overheating and/or [[electrical:12v:alternator#sudden_disconnection|sudden shutdown]].
+==== flooded lead-acid ====
+FLA batteries can accept up to [[electrical:12v:battery_capacity|C]]/5 in [[electrical:12v:charging|Bulk stage]].
+Example:  a 200Ah FLA battery bank will pull up to 40A((200Ah/5)) in Bulk charging.  An isolator rated for constant duty at 40A((likely with peak tolerance of 60A or so)) would be sufficient.((assuming you aren't applying heavy loads like a microwave while driving))
+==== AGM lead-acid ====
+Consumer-grade AGM batteries typically will accept C/5 - C/3.
+Example:  a 200Ah AGM bank will pull up to 67A in Bulk.  A 75A isolator((100A peak)) would be sufficient.
+Note:  high-end AGM like Lifeline, Odyssey, Rolls, etc, can pull massive current when charging. 200A+ would be possible for the example bank and could shorten the life of a stock alternator.
+==== lithium ====
+Lithium also has the ability to accept massive amounts of charging. It will do so across the entire charging range, as lithium does not have an Absorption phase the way lead-acid does.
+Example:  200Ah of lithium could easily accept 200Ah+.  There are mitigating factors, however.
+  * Because lithium can use about 80% of it's capacity instead of 50% for lead-acid, 120Ah of lithium is a common replacement for 200Ah lead-acid banks.  So the lithium bank would "only" draw 120A instead of 200A.
+  * drop-in lithium banks like [[https://amzn.to/2J10vpZ|Battleborn]] have a battery monitoring system (bms) to shut down charging if current exceeds specs.
+==== sudden disconnection ====
+**Sudden disconnection of a large load((including a charging battery)) when the alternator is running** can damage the alternator and any operating chassis electronics.  Sudden disconnection can occur when:
+  * an isolator shuts off due to current beyond it's rating
+  * a BMS shuts off lithium charging.  This can include overvoltage, overcurrent, temperature extremes, etc.
@@ Line 69: / Line 103: @@
   * a higher-output alternator will put out more power
   * a different **voltage regulator** for older vehicles, [[http://www.cheaprvliving.com/forums/Thread-Your-Vehicles-voltage-regulator|as demonstrated by SternWake]], increases the voltage available for charging but also increases the coach voltage.
-  * a  [[http://www.sterling-power-usa.com|Sterling]] "fake load" regulator will cause the alternator to put out more amps and then will DC-DC convert the voltage up to correct charging range.((http://www.sterling-power-usa.com/library/What%20is%20an%20alternator%20to%20battery%20charger.pdf)).  This is the opposite direction of how [[electrical:solar:charge_controller|MPPT charging]] works.
+  * a  [[http://www.sterling-power-usa.com|Sterling]] "fake load" regulator will cause the alternator to put out more amps and then will DC-DC convert the voltage up to correct charging range.((http://www.sterling-power-usa.com/library/What%20is%20an%20alternator%20to%20battery%20charger.pdf)).  This is the opposite direction of how [[electrical:solar:charge_controller|MPPT charging]] works.  Also see [[electrical:12v:b2b|b2b chargers]].
 ===== using the coach battery only =====
-A simple possible approach would be to replace the starter battery with a marine or AGM battery.((http://www.cheaprvliving.com/forums/Thread-Easiest-simplest-cheapest-power-set-up))
+A simple possible approach would be to [[electrical:solar:shallow_cycling|replace the starter battery with a marine or AGM battery]].((http://www.cheaprvliving.com/forums/Thread-Easiest-simplest-cheapest-power-set-up))
 ===== further reading =====

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