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electrical:12v:alternator_charging_rates

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electrical:12v:alternator_charging_rates [2023/09/10 13:13]
frater_secessus [estimating combiner charging] 		electrical:12v:alternator_charging_rates [2023/09/10 13:25] (current)
frater_secessus [estimating combiner charging]
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-====== How much will by battery charge by alternator? ======+====== How much will my battery charge by alternator? ======
  
 This should be easy, right? This should be easy, right?
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 We know the time part because we're the ones driving.  But the charge rate part can be hard to predict with any certainty;  this is especially true for combiner ("split charger") charging. We know the time part because we're the ones driving.  But the charge rate part can be hard to predict with any certainty;  this is especially true for combiner ("split charger") charging.
- 
  
 ===== TLDR ===== ===== TLDR =====
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 ===== estimating DC-DC charging ===== ===== estimating DC-DC charging =====
  
-DC-DC charging rates are more predictable because of how they work.  A 20A DC-DC will likely pump 20A into the bank most of the time.    So 3 hours driving x 20A = 60Ah returned to the battery bank.  The price of this predictability (and other features) is... price.  +DC-DC charging rates are more predictable because of how they work.  A 20A DC-DC will likely pump 20A into the bank most of the time.    So 1/2 hour driving x 20A = 10Ah returned to the battery bank.  The price of this predictability (and other features) is... price.  
  
-If you need predictable charging then DC-DC is likely the answer.+If you need predictable charging then DC-DC is likely the answer.  There are [[electrical:12v:alternator#limitations|other scenarios]] where DC-DC is effectively required.
  
 ===== estimating combiner charging ===== ===== estimating combiner charging =====
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       * in the broad "flat" portion of the voltage curve (20%-80 state of charge) current will likely stabilize around 0.2C.  We could use 0.2C as our average rate.  10Ah replaced.        * in the broad "flat" portion of the voltage curve (20%-80 state of charge) current will likely stabilize around 0.2C.  We could use 0.2C as our average rate.  10Ah replaced. 
  
 +==== in the real world ====
 +
 +In most installs this variability isn't a major issue:
  
 +  * combiner charging is commonly paired with solar charging (also highly variable!) 
 +  * alternator charging is often a backup or "nice when you can get it" charging source.  Exception:  there are [[electrical:12v:mandatory_solar|scenarios that depend on it]]. 
  
  
electrical/12v/alternator_charging_rates.1694366029.txt.gz · Last modified: 2023/09/10 13:13 by frater_secessus

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