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opinion:frater_secessus:self-heated_lifepo4

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opinion:frater_secessus:self-heated_lifepo4 [2023/09/03 16:22]
frater_secessus [when self-heated might be preferable]
opinion:frater_secessus:self-heated_lifepo4 [2023/10/17 15:13]
frater_secessus [how the approaches work]
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   - allow incoming power only to the internal heaters, typically ~60w   - allow incoming power only to the internal heaters, typically ~60w
   - when cell temps are >freezing charging is re-enabled   - when cell temps are >freezing charging is re-enabled
-  - optional:  heating may continue until some warmer setpoint, typically ~50F when this feature is utilized+  - optional:  heating may continue until some warmer setpoint, typically 40F-50F when this feature is utilized
  
 This means //warming only happens when charging is present// This may or may not be what you want.  This means //warming only happens when charging is present// This may or may not be what you want. 
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-With "soft" charging like a small solar setup it's a wash.  a matter of preference and cost.    +With "soft" charging like a small solar setup it's a wash.  a matter of preference and cost.   But in some specific use cases one approach might work better. 
- +
-In some specific use cases one approach might be better-suited than the other +
  
  
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 With robust charging (alternator and/or bigger solar) there can be charging opportunities lost with self-heated batteries in freezing conditions.   With robust charging (alternator and/or bigger solar) there can be charging opportunities lost with self-heated batteries in freezing conditions.  
  
-Imagine +Imagine the following scenario
  
-* freezing overnights followed by a half-hour drive in the morning with a 30A DC-DC.  +  * freezing overnights followed by a half-hour drive in the morning with a 30A DC-DC.  
-* a battery with warming pad that consumed 60Wh overnight to stay above freezing, vs +  * a battery with warming pad that consumed 60Wh overnight to stay above freezing, vs 
-* a self-heating battery that is below freezing in the morning+  * a self-heating battery that is below freezing in the morning
  
 The externally warmed bank accepts current immediately and takes **15Ah of recharge**.  So after recouping the 60Wh used overnight it's **net +132Wh**. The externally warmed bank accepts current immediately and takes **15Ah of recharge**.  So after recouping the 60Wh used overnight it's **net +132Wh**.
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 With 50A charging it's 260Wh net vs 107Wh net. . With 50A charging it's 260Wh net vs 107Wh net. .
  
-If one was charging by alternator only and only driving to/from work while stealthing in freezing weather it's conceivable the self-heated batt would get *never get charged at allbecause it wouldn't have time to get out of the heating phase.+If one was charging by alternator only and only driving to/from work while stealthing in freezing weather it's conceivable the self-heated batt would get //never get charged at all// because it wouldn't have time to get out of the heating phase.
  
 ==== specific configurations ==== ==== specific configurations ====
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   * how much charging would I miss out on because the bank is taking only 60w to run the heaters instead of taking everything I can throw at it?; and   * how much charging would I miss out on because the bank is taking only 60w to run the heaters instead of taking everything I can throw at it?; and
-   * how does this compare to the Wh required to keep the bank above freezing when no charging is present? +  * how does this compare to the Wh required to keep the bank above freezing when no charging is present? 
-   * do I need greater configurability than the built-in heater allows?+  * do I need greater configurability than the built-in heater allows
 +  * do I have the interest or ability to DIY?
  
 ===== further reading ===== ===== further reading =====
opinion/frater_secessus/self-heated_lifepo4.txt · Last modified: 2023/10/17 15:13 by frater_secessus