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electrical:12v:alternator_details [2022/12/19 11:32]
frater_secessus [types of alternator] 		electrical:12v:alternator_details [2022/12/19 11:52]
frater_secessus [current]
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   * **heat**, which is the destroyer of alternators   * **heat**, which is the destroyer of alternators
  
-There is no way to know the actual number of amps you can pull from the alternator in any given condition.  A general rule would be that **if the output voltage is lower than normal the alternator is stressed**.  + 
 +In the absence of further information one might use these rules of thumb.   House loads here means both house bank charging and any loads demanded by the user.  
 + 
 +  * **at idle** house loads **≤25% of rated output**.  Note:  this is about stopping at red lights or in traffic;  idling the engine to charge batteries is not recommended.  For our 140A alternator this would be 35A. 
 +  * **while driving** loads ≤33% of rated output.  For our 140A alternator this would be 47A.   
 +  * if **alternator output  voltage drops below normal** the alternator is overloaded 
 + 
 + 
 +The accurate way would be to  
 + 
 +  - acquire the output chart for your alternator 
 +  - use a clamp meter to see what current the chassis draws with blower on, lights on, etc at a given engine  rpm 
 +  - do the math:  [output rating at that rpm / 2] to get continuous output rating at that rpm.  Subtract chassis loads.  The remainder is what you have left over to use.  
 + 
 + 
 + 
 +There is no way to know the actual number of amps you can pull from the alternator in any given condition without .  A general rule would be that **if the output voltage is lower than normal the alternator is stressed**.  
  
 While paying attention to the above rule, you might use some other rules of thumb: While paying attention to the above rule, you might use some other rules of thumb:
  
-  * **at idle** loads should be ≤25% of rated output.  Note:  this is about stopping at red lights or in traffic;  idling the engine to charge batteries is not recommended.  For our 140A alternator this would be 35A. 
-  * **while driving** loads should be ≤50% of rated output.  For our 140A alternator this would be 70A.   
  
  
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-==== Heavy duty / high output ====+===== Heavy duty / high output =====
  
 Alternators can be built in heavy duty configuration, which typically connotes: Alternators can be built in heavy duty configuration, which typically connotes:
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-==== large case / small case ====+===== 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.   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.  
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 Further reading: Further reading:
  
-  * [[https://www.youtube.com/watch?v=Kw17G76JnWQ|Small case vs Large case alternators. Know your application!|| (youtube) +  * [[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))+
  
  
electrical/12v/alternator_details.txt · Last modified: 2024/03/29 19:48 by frater_secessus

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