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electrical:12v:drop-in_lifepo4 [2024/03/10 10:50]
frater_secessus [myth: you can't charge Li with a lead battery charger] power supply 		electrical:12v:drop-in_lifepo4 [2024/04/12 23:02] (current)
frater_secessus [bluetooth]
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   * the flat voltage curve makes gauging SoC by voltage extremely challenging, and battery "gauges" designed for lead chemistry batteries will not work. An amp-counting [[electrical:12v:battery_monitor|battery monitor]] will be more useful with Li.    * the flat voltage curve makes gauging SoC by voltage extremely challenging, and battery "gauges" designed for lead chemistry batteries will not work. An amp-counting [[electrical:12v:battery_monitor|battery monitor]] will be more useful with Li. 
  
 +===== sizing the bank =====
  
 +Other than cost, there is little downside to having a larger LiFePO4 bank.(([[electrical:12v:directcharginglfp|direct-charging from alternator]] would require some thought))  Upsides include:
 +
 +  * greater [[opinion:solar:sizing.walkthrough#days_of_autonomy|autonomy]] when charging is absent or limited due to poor solar conditions
 +  * supporting larger discharge current - [[electrical:12v:battery_capacity|0.5C]] is a common max spec.  So a 200Ah LFP could support 100A loads((0.5 x 200Ah)) while a 100Ah could only support 50A.  
 +  * safely accepting larger charging currents when charging time is limited.  Charging specs vary between 0.2C to 0.5C;  [[electrical:12v:drop-in_lifepo4#an_example_of_long_life|0.4C]] seems to be a good balance between longevity and charging time.  200Ah could accept 80A from the alternator while 100Ah could only accept 40A.  
  
  
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 === testing your isolator with Li === === testing your isolator with Li ===
  
-see [[electrical:12v:directcharginglfp#assessing_your_setup_for_direct_alternator_charging|this section]]+see [[electrical:12v:directcharginglfp#assessing_your_own_setup_for_direct_alternator_charging|this section]]
  
 ==== but that Victron video ==== ==== but that Victron video ====
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 >> For belt-and-suspenders you could add a $10 12v temp controller or NO thermal switch in series [with the disabling method].   Stick the probe (or switch) on the bank and only complete the [disabling ] circuit when the ignition is on **and** measured temp >0C or >2C or whatever you prefer.  >> For belt-and-suspenders you could add a $10 12v temp controller or NO thermal switch in series [with the disabling method].   Stick the probe (or switch) on the bank and only complete the [disabling ] circuit when the ignition is on **and** measured temp >0C or >2C or whatever you prefer. 
 +
 +Note that some chargers have built-in low-temp charging cutoff already.  
  
  
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 Some batteries have BMS with bluetooth or other forms of connectivity.  With these you would be able to see more information, like individual cell balance, statistics, setting and the status of any protections.  Some batteries have BMS with bluetooth or other forms of connectivity.  With these you would be able to see more information, like individual cell balance, statistics, setting and the status of any protections. 
  
 +Having visibility into the state of the BMS/cells might be useful for tech geeks, but often muddies the waters for non-technical customers.  Lack of BT is not a dealbreaker. 
  
  
electrical/12v/drop-in_lifepo4.1710082215.txt.gz ยท Last modified: 2024/03/10 10:50 by frater_secessus

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