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electrical:12v:drop-in_lifepo4 [2024/03/18 13:29]
frater_secessus [sizing the bank] autonomy clarification 		electrical:12v:drop-in_lifepo4 [2024/05/21 22:08] (current)
frater_secessus [myth: you have to charge Li to 100%]
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   * greater [[opinion:solar:sizing.walkthrough#days_of_autonomy|autonomy]] when charging is absent or limited due to poor solar conditions   * 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.  +  * 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.     * 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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   * to top-balance cells((to the degree this works))   * to top-balance cells((to the degree this works))
  
 +==== myth:  lithium batteries draw the full current until they are almost full ====
 +
 +
 +  * both lead and li chemistry charge acceptance [[electrical:12v:directcharginglfp#current_demands_of_dc-dc_chargers_vs_isolators|will taper]] when charged by a [[electrical:12v:alternator|relay/isolator]], and 
 +  * both will charge ~at [[electrical:12v:b2b|a DC-DC charger]]'s rated output until Absorption voltage is reached
 +
 +If we observed closely we //would// see some differences:  the LFP taper is shaped a bit differently, and that lead Absorption tends to start earlier and last longer.  
  
 ==== myth:  if you don't charge to 14.4v the cells won't balance ==== ==== myth:  if you don't charge to 14.4v the cells won't balance ====
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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_lifepo4.1710782996.txt.gz ยท Last modified: 2024/03/18 13:29 by frater_secessus

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