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--- electrical:12v:alternator_details [2022/05/20 23:32]
frater_secessus [types of alternator]
+++ electrical:12v:alternator_details [2022/12/19 11:32]
frater_secessus [types of alternator]
@@ Line 42: / Line 42: @@
-===== types of alternator =====
+==== regulation ====
 **Standard alternators** are the simplest model like the 14.0v model in the example above.  They are called //internally-regulated// because the voltage regulator is built into the alternator itself.
@@ Line 54: / Line 54: @@
 **Smart alternators** are designed to support fuel mileage efforts.  Voltage might plummet during full accelleration (to free up engine power) then spike quite high in other conditions.  This wide variance means a DC-DC charger is required.  Note:  some smart alternators have a setting that allows them to be function like a standard alternator.
-**Heavy duty / high output alternators** - any of the above alternators can be build in heavy duty configuration, which typically connotes:
+==== Heavy duty / high output ====
+Alternators can be built in heavy duty configuration, which typically connotes:
   * higher current rating
@@ Line 60: / Line 65: @@
   * ability to make more power in idling scenarios, which is useful for police vehicles, ambulances, and other vehicles that need to idle for long periods of time.
-HD alternators for any particular vehicle are typically bolt-in with no modifications required.  They do cost somewhat more.   The labor cost would remain the same so some people choose to upgrade the alternator when/if the OEM one fails.
+HD alternators for any particular vehicle may be bolt-ins with no modifications required.  They do cost somewhat more.   The labor cost would remain the same so some people choose to upgrade the alternator when/if the OEM one fails.
+==== large case / small case ====
+Alternator cases come in two general sizes:  large and small.  Most vehicles come stock with small case alternators because they are easier to "package" (fit into the available space).  Semis, boats, and other vehicles with fewer space limitations may use large case alternators, allowing for more internal cooling, larger or more separated components, ease of repair, higher constant duty outputs, etc.
+One is not //better// than the other;  they are meant for different applications.
+The mounting bolt pattern may be the same or it may  require a different mount.  Pulleys, belts, and/or belt lengths may need to be changed.
+Further reading:
+  * [[https://www.youtube.com/watch?v=Kw17G76JnWQ|Small case vs Large case alternators. Know your application!|| (youtube)
+=== identification ===
+There are some rules of thumb one can use to visually identify some large and small case alts.
+**GM-style alternators**
+**Ford-style alternators**
+{{ https://alternatorparts.com/images/3g_lg_vs_sm/612short.jpg}}`
+> on small case alternators there are four small holes per each of the three ribs radiating from the center. On the large case, there are only two holes on the same ribs((https://alternatorparts.com/how-to-id-ford-alternator-large-case-or-small-case-faq.html))
 ===== DUVAC =====
-Some older RVs come with DUVAC (DUal Voltage Alternator Control)((https://www.countrycoachforums.com/index.php?PHPSESSID=3ggkjl41c5lrkrerduih87oeif&topic=6840.msg34665#msg34665)) setups, which use separate voltage-sense wires for the house bank.
+Some older Class A and C RVs came with DUVAC (DUal Voltage Alternator Control)((https://www.countrycoachforums.com/index.php?PHPSESSID=3ggkjl41c5lrkrerduih87oeif&topic=6840.msg34665#msg34665)) setups, which use separate voltage-sensnig wires for the house bank.
 > This Duvac system that Leese Neville came up with was a completely integrated dual battery/isolator setup that was “state-of-the-art” in ’99((diode-based isolators)) but soon was obsoleted by newer better technology.((voltage-sensing relays and DC_DC chargers))((https://www.foreforums.com/index.php?PHPSESSID=bs0n0psbr6rrvd240rv4ijvg1p&topic=33250.msg432529#msg432529))
+> ...the primary reason for DUVAC is to allow the alternator to "compensate" for the voltage loss (turned into heat) in the old generation **diode-based battery isolators**. There is approximately a .7 VDC loss through the battery isolator. The sense wire/terminal allows voltage on the battery side of the isolator to control the alternator voltage.((https://www.irv2.com/forums/f115/eliminating-the-duvac-system-539048.html#post5772417))
 {As far as I can tell this was a workaround from when many isolators were diode-based so the alternator could not "see" aux battery voltage on the combined circuit((https://www.foreforums.com/index.php?PHPSESSID=bs0n0psbr6rrvd240rv4ijvg1p&topic=33250.msg300875#msg300875)) -- secessus}  See [[https://www.dixie-electric.com/tsb/TSB_704.pdf|this TSB]]. (PDF)

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