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electrical:12v:alternator_details [2023/09/22 15:09]
frater_secessus [sudden load disconnect] load dump 		electrical:12v:alternator_details [2025/02/26 11:29] (current)
frater_secessus [Heavy duty / high output]
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 **Externally-regulated alternators** are alternators where the regulation function is physically separated from the alternator.  There may be a stand-alone external regulator or the engine ECU may assume those duties.   **Externally-regulated alternators** are alternators where the regulation function is physically separated from the alternator.  There may be a stand-alone external regulator or the engine ECU may assume those duties.  
  
-In a camper/RV context //an externally-regulated alternator// typically means an **aftermarket regulator**, like Balmar - voltage often provides [[electrical:12v:charging|multistage (smart) charging]], temperature-based derating, etc.  Read on.  +see [[electrical:12v:alternator_details#external_regulation|External Regulation]] below
- +
-A separate alternator (see below) is not required to use external regulation but that is a common scenario.  If one externally regulates the vehicle's sole alternator the chassis could be exposed to higher or lower voltages than it was designed for.  +
- +
-Common external regulators include: +
- +
-  * Balmar ARS-5 (no external voltage sensing) +
-  * Balmar MC-614 (external voltage sensing) +
-  * Xantrex Xar (no external voltage sensing) +
-  * Wakespeed WS500 (CANBUS)+
  
 === tricking the regulator === === tricking the regulator ===
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-=== heat ===+==== heat ====
  
  
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 > Temp sensor should be measuring as close to the stator as possible((https://forums.sailboatowners.com/threads/alternator-temperatures.1249934414/post-1780143)) > Temp sensor should be measuring as close to the stator as possible((https://forums.sailboatowners.com/threads/alternator-temperatures.1249934414/post-1780143))
  
-A common rule of thumb for a safe upper limit on case temps is 100C/212F.((https://www.cruisersforum.com/forums/f14/balmar-alternator-temperate-protection-settings-241443.html)) +A common rule of thumb for a safe upper limit on case temps is 100C/212F((https://www.cruisersforum.com/forums/f14/balmar-alternator-temperate-protection-settings-241443.html)), although more conservative temperatures might be advisable. 
  
 {{ https://img.mousetrap.net/misc/SAEAltTemps.jpg?100}}Critical internals will be hotter than the case itself.  For example, during [[electrical:12v:drop-in_lifepo4#but_that_Victron_video|the infamous Victron video]] both internal and external temps were given for the Balmar setup making 50A @ 2,100rpm.  The case was 42C (108F) while the internals were 74C (165F).  This alt was on a bench rather than mounted to a hot engine block.  See table at right for examples of external/internal temps observed during lab testing.((https://www.cruisersforum.com/forums/f14/alternator-temp-what-is-normal-range-228245-2.html#post3114736))  {{ https://img.mousetrap.net/misc/SAEAltTemps.jpg?100}}Critical internals will be hotter than the case itself.  For example, during [[electrical:12v:drop-in_lifepo4#but_that_Victron_video|the infamous Victron video]] both internal and external temps were given for the Balmar setup making 50A @ 2,100rpm.  The case was 42C (108F) while the internals were 74C (165F).  This alt was on a bench rather than mounted to a hot engine block.  See table at right for examples of external/internal temps observed during lab testing.((https://www.cruisersforum.com/forums/f14/alternator-temp-what-is-normal-range-228245-2.html#post3114736)) 
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 === thermal switches === === thermal switches ===
  
-In [[https://www.youtube.com/watch?v=bjeHJd6OO2Y&lc=Ugyusa6wH9p3jNMKbmh4AaABAg.9m5OeSgBRtB9m5UO1ANIfF|a comment]] on [[https://www.youtube.com/watch?v=bjeHJd6OO2Y|an excellent video about charging lithium from the alternator]] WorkingOnExploring talks about adding overtemp protection with:+In [[https://www.youtube.com/watch?v=bjeHJd6OO2Y&lc=Ugyusa6wH9p3jNMKbmh4AaABAg.9m5OeSgBRtB9m5UO1ANIfF|a comment]] on [[https://www.youtube.com/watch?v=bjeHJd6OO2Y|an excellent video about charging lithium from the alternator]] WorkingOnExploring talks about adding overtemp protection with a thermal switch (a small bimetallic switch):((see [[https://www.youtube.com/watch?v=kF4Yxo9C9DM|this teardown and demo video]]  on youtube)) 
  
 >>  [[https://amzn.to/3luTwwx|a KSD9700 120C]], normally closed thermal switch epoxied to your alternator case. That way, if some abnormal event occurred and the alternator overheated, it could deactivate the [combiner] till the alternator cooled. It would likely cost less than $20 to install this thermal safety. >>  [[https://amzn.to/3luTwwx|a KSD9700 120C]], normally closed thermal switch epoxied to your alternator case. That way, if some abnormal event occurred and the alternator overheated, it could deactivate the [combiner] till the alternator cooled. It would likely cost less than $20 to install this thermal safety.
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 The idea here is to run the relay's control circuit((manual or D+ wire, //not// the charging wire)) through the **N**ormally-**C**losed((ie,circuit completed)) thermal switch.  When the switch hits the defined temperature the circuit opens((breaks)) and power to the combiner is cut off;  house bank charging from the alternator is stopped. The switch will typically reset when temperature drops by ~25%; read the datasheet for your switch for specific details.  The idea here is to run the relay's control circuit((manual or D+ wire, //not// the charging wire)) through the **N**ormally-**C**losed((ie,circuit completed)) thermal switch.  When the switch hits the defined temperature the circuit opens((breaks)) and power to the combiner is cut off;  house bank charging from the alternator is stopped. The switch will typically reset when temperature drops by ~25%; read the datasheet for your switch for specific details. 
  
-The thermal switch is a tiny bimetallic device.  See [[https://www.youtube.com/watch?v=kF4Yxo9C9DM|this teardown and demo video]] (youtube).+If one had a DC with a current-limiting function ([[electrical:12v:b2b#renogy1|renogy's 20-40-60A models]], for example) or DC-DC in parallel one could use two different-spec switches to achieve staged charging.  Using placeholder temps: 
 + 
 +  - run an aggressive charging setup full blast  
 +  - at 90C engage current limiting 
 +  - at 120C disable charging completely 
 + 
 + 
  
 Note:  120C = 248F.  Other temps like 90C (194F) and 100C (212C) are available and may be gentler on the alternator. Because the alternator is mounted to the block the alternator case may be at the ~same temp as the block.  Check case temps when engine has been running to get a feel for how hot the case should be, preferably at the location the diodes are heat-sinked to the alternator case.((https://forums.sailboatowners.com/threads/alternator-temperature.1249925187/post-1644191))    Note:  120C = 248F.  Other temps like 90C (194F) and 100C (212C) are available and may be gentler on the alternator. Because the alternator is mounted to the block the alternator case may be at the ~same temp as the block.  Check case temps when engine has been running to get a feel for how hot the case should be, preferably at the location the diodes are heat-sinked to the alternator case.((https://forums.sailboatowners.com/threads/alternator-temperature.1249925187/post-1644191))   
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   * The Balmar MC-612 with temp sensor starts derating at 107C.((https://balmar.net/wp-content/uploads/2016/02/MC-612-Regulator-Manual-2005-2009.pdf))  It can derate ~55%.((https://www.irv2.com/forums/f87/alternator-burn-out-from-lithium-batteries-558284-8.html#post6426941))   * The Balmar MC-612 with temp sensor starts derating at 107C.((https://balmar.net/wp-content/uploads/2016/02/MC-612-Regulator-Manual-2005-2009.pdf))  It can derate ~55%.((https://www.irv2.com/forums/f87/alternator-burn-out-from-lithium-batteries-558284-8.html#post6426941))
   * DC Power Solutions alternators are ok to 107C.((https://www.cruisersforum.com/forums/f14/alternator-temperature-169339.html#post2164617))   * DC Power Solutions alternators are ok to 107C.((https://www.cruisersforum.com/forums/f14/alternator-temperature-169339.html#post2164617))
 +
 +=== idling to charge house batteries ===
 +
 +Idling the engine to charge house batteries is a perfect storm of **underperformance**
 +
 +  * the alternator is spinning too slowly to make the CDR
 +
 +and heat 
 +
 +  * the alternator is spinning too slowly for internal cooling fans to work well
 +  * the alternator is producing more heat than power due to inefficiency
 +  * there is no airflow from forward movement to directly cool the alternator...
 +  * ... or to remove superheated air under the hood 
 +
 +The situation is bad enough with relays, but even worse worse with DC-DC because
 +
 +  * they tend to hold full output for hours on end rather than tapering
 +  * when the alternator struggles and voltage drops the DC-DC will demand //more// current to make its output target.  Hopefully the charger has a minimum chassis voltage for operation and will not drag the chassis down excessively
 +
 +
  
 === anecdote === === anecdote ===
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 ==== external regulation ==== ==== external regulation ====
  
-External regulation can provide overtemperature protection (see section on Heat above), and can also cause the alternator to behave like a smart charger with [[electrical:12v:charging|multistage charging]]. +External regulation can provide overtemperature protection (see section on Heat above), current limiting, and can also cause the alternator to behave like a smart charger with [[electrical:12v:charging|multistage charging]].  
 + 
 + 
 +In a camper/RV context //an externally-regulated alternator// typically means an **aftermarket external regulator** controlling a **dedicated secondary alternator**.((on boats there is typically one externally-regulated alternator that runs the electrics and charges the house bank.  Modern land vehicles are likely less tolerant of the alternator doing things the ECU did not command.))  Depending on the implementation external regulation might provide: 
 + 
 +  * configurable current levels and/or voltage setpoints 
 +  * [[electrical:12v:charging|multistage (smart) charging]] 
 +  * temperature monitoring so maximal current can be extracted without overheating 
 +  * RPM-based output limits 
 +  * slowly ramping up current to avoid belt slippage/damage 
 +  * shutoff when commanded by BMS 
 +  * CANBUS and other communication 
 +  * etc 
 + 
 +External regulators include: 
 + 
 +  * Balmar ARS-5 (no external voltage sensing) 
 +  * Balmar MC-614 (external voltage sensing) 
 +  * Xantrex Xar (no external voltage sensing) 
 +  * Wakespeed WS500 (CANBUS) 
 +  * [[https://theyachtrigger.com/arco-zeus-alternator-regulator/|Arco Zeus]] - new to market 
 +  * [[https://www.mastervolt.com/products/alpha-pro-mb-charge-regulator1/alpha-pro-iii/|Mastervolt]], more often seen in marine installs 
 +  * [[https://sterling-power.com/collections/alternator-regulators|Sterling]]
  
  
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 [[https://www.nationsstarteralternator.com/|Nations]] and similar alternator builders make alternators for specialty uses.  [[https://www.nationsstarteralternator.com/|Nations]] and similar alternator builders make alternators for specialty uses. 
  
-Note that increasing alternator output may require upgrading stock chassis wiring: +=== big three === 
 + 
 + 
 +Note that increasing alternator output may require upgrading stock chassis wiring.  Often called "the Big Three": 
 + 
 +  - POS from alternator to starter battery 
 +  - NEG from starter battery to chassis 
 +  - NEG from chassis to engine block
  
 >> To run a [high output] alternator, ALL of your engine's factory high current cabling will need to be [sized] to support it, including engine and starting battery grounds, and alternator positive. -- MechEngrSGH((https://www.irv2.com/forums/f87/alternator-burn-out-from-lithium-batteries-558284-8.html#post6428559)) >> To run a [high output] alternator, ALL of your engine's factory high current cabling will need to be [sized] to support it, including engine and starting battery grounds, and alternator positive. -- MechEngrSGH((https://www.irv2.com/forums/f87/alternator-burn-out-from-lithium-batteries-558284-8.html#post6428559))
 +
 +In addition, the wiring from the starter batt or alternator to the house battery bank may require upsizing to actually get that current where you want it to go. 
 +
 +
 +
 ==== Idle optimized ==== ==== Idle optimized ====
  
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 [[https://youtu.be/uwrG3gUdDT8?t=725|This behavior surprised Mortons on the Move]], thwarting their alternator-charging plans.  [[https://youtu.be/uwrG3gUdDT8?t=725|This behavior surprised Mortons on the Move]], thwarting their alternator-charging plans. 
  
 +Known configurations:
  
   * 397A = 220A + 157A   * 397A = 220A + 157A
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 +== GM ==
  
 +Information is limited, but GM factory dual alt setups appear to run the way one would expect in the first place, with load shared between them:
 +
 +> The two alternators are controlled over a common circuit from the ECM so they cannot be controlled independently. The ECM cannot shut one down and let the other one run. It is both or neither.((https://www.duramaxforum.com/threads/dual-alternator.934098/post-11906770))
 +
 +[[https://www.duramaxforum.com/threads/dual-alternator.934098/post-11906642|This upfitters guide excerpt]] contains additional information.
 ==== DUVAC ==== ==== DUVAC ====
  
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 >> Alternator is chugging along, delivering 50 Amps. Suddenly, the output is disconnected. Since the regulator has a time constant, plus the field current can’t collapse instantly, plus stator windings, being coils, therefore inductive, they hold energy, there becomes a high positive voltage at the B+ port to keep the current flowing for a time. This transient energy may manifest itself in switch arcs, and other undesirable voltage excursions.((https://www.cruisersforum.com/forums/f166/myth-of-alternator-damage-cause-by-bms-disconnect-258292-6.html#post3532355))  >> Alternator is chugging along, delivering 50 Amps. Suddenly, the output is disconnected. Since the regulator has a time constant, plus the field current can’t collapse instantly, plus stator windings, being coils, therefore inductive, they hold energy, there becomes a high positive voltage at the B+ port to keep the current flowing for a time. This transient energy may manifest itself in switch arcs, and other undesirable voltage excursions.((https://www.cruisersforum.com/forums/f166/myth-of-alternator-damage-cause-by-bms-disconnect-258292-6.html#post3532355)) 
  
-This is called a //load dump//; the load is dumped and there is nowhere for power in the alternator to go.  As we will see, in normal installs there //are// places for the power in the alternator to go. +This is called a //load dump//; the load is dumped (demand reduced to 0A) and there is nowhere for power in the alternator to go.  As we will see, in normal installs there //are// places for the power in the alternator to go. 
  
 **In practice**: **In practice**:
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 ==== exception:  dedicated secondary alternators ==== ==== exception:  dedicated secondary alternators ====
  
-Secondary alternators dedicated to Li charging will not have a starter battery inline to absorb spikes.   +Secondary alternators dedicated to Li charging will not have a starter battery or other loads inline to absorb spikes.  In this case the owner might:
- +
- +
-In this case the owner might:+
  
   * use a CANBUS or similar setup where the BMS can notify the alternator regulator of imminent shutdown ahead of time to allow orderly reduction of power; or   * use a CANBUS or similar setup where the BMS can notify the alternator regulator of imminent shutdown ahead of time to allow orderly reduction of power; or
electrical/12v/alternator_details.1695409790.txt.gz · Last modified: 2023/09/22 15:09 by frater_secessus

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