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electrical:12v:drop-in_lifepo4 [2025/03/18 13:27]
frater_secessus [myth: you must use DC-DC for alternator charging Li] 		electrical:12v:drop-in_lifepo4 [2025/05/04 10:19] (current)
frater_secessus [drawbacks of lithium]
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 ===== drawbacks of lithium ===== ===== drawbacks of lithium =====
  
-  * Li is relatively expensive up front+  * Li has (historically at least) been relatively expensive up front.  Prices started plummeting somewhere around 2024.
   * Li cells need a [[#bms_functions|BMS]] to protect them from damage.((some DIYers run Li "barefoot" (without a BMS) )) For example, Li can be damaged by overvoltage, undervoltage, charging below freezing (32F), etc.  Some batteries have low-temp cutoff and/or internal heating to address the cold-charging limitation.  Most Drop-in Lithium batteries will have a BMS integrated into them, but raw cells do not.   * Li cells need a [[#bms_functions|BMS]] to protect them from damage.((some DIYers run Li "barefoot" (without a BMS) )) For example, Li can be damaged by overvoltage, undervoltage, charging below freezing (32F), etc.  Some batteries have low-temp cutoff and/or internal heating to address the cold-charging limitation.  Most Drop-in Lithium batteries will have a BMS integrated into them, but raw cells do not.
   * Li can be **damaged** by long duration at full charge or high voltage, or high ambient temperatures   * Li can be **damaged** by long duration at full charge or high voltage, or high ambient temperatures
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   * going into a period where you will need max capacity   * going into a period where you will need max capacity
   * to perform a capacity test   * to perform a capacity test
-  * to reset the BMS amp/SoC counter+  * to [[electrical:12v:battery_monitor#drift_and_reset|reset the BMS amp/SoC counter]]
   * to top-balance cells((to the degree this works))   * to top-balance cells((to the degree this works))
  
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   * **Absorption voltage** (Vabs) - whatever charging voltage your battery manufacturer recommends.((see the section on longevity in this article))   * **Absorption voltage** (Vabs) - whatever charging voltage your battery manufacturer recommends.((see the section on longevity in this article))
   * **Absorption duration** - whatever the battery manufacturer recommends, typically 0 to 20 minutes.((charging voltages ≥14.0v typically require no absorption duration at all))   * **Absorption duration** - whatever the battery manufacturer recommends, typically 0 to 20 minutes.((charging voltages ≥14.0v typically require no absorption duration at all))
-  * **Float voltage** (Vfloat) - Something like 13.4v((3.35vpc)) is a good compromise. See the discussion on float below.+  * **Float voltage** (Vfloat) - Something like 13.3v-13.4v((3.35vpc)) is a good compromise. See the discussion on float below.
   * **Absorption reconnect** - this voltage is the setpoint below which Absorption(("boost" in Renogy/EpEver nomenclature)) is restarted. Normally in a solar configuration Vfloat is held until sun goes down, solar conditions otherwise deteriorate, or a load is applied that is more than the solar can support.  Start with a value like 13.2v and see how your system behaves.  Adjust as needed.    * **Absorption reconnect** - this voltage is the setpoint below which Absorption(("boost" in Renogy/EpEver nomenclature)) is restarted. Normally in a solar configuration Vfloat is held until sun goes down, solar conditions otherwise deteriorate, or a load is applied that is more than the solar can support.  Start with a value like 13.2v and see how your system behaves.  Adjust as needed. 
   * **Equalize voltage** (Veq) - Li does not require equalization.  If it cannot be disabled in the controller it is common to set Veq the same as Vabs so it becomes a non-issue.((some folks who charge to lower voltages like 13.6v may use Veq to raise bank voltage into the 14s for various purposes.  See the section on longevity.))     * **Equalize voltage** (Veq) - Li does not require equalization.  If it cannot be disabled in the controller it is common to set Veq the same as Vabs so it becomes a non-issue.((some folks who charge to lower voltages like 13.6v may use Veq to raise bank voltage into the 14s for various purposes.  See the section on longevity.))  
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 >> Yes, you can.  Under most circumstances you don't even need to modify your system. >> Yes, you can.  Under most circumstances you don't even need to modify your system.
  
-They do recommend [[electrical:12v:alternator#lithium-specific|a BIM]] or [[electrical:12v:b2b|DC-DC charger]] //for banks >300Ah//.+They do recommend [[electrical:12v:alternator#lithium-specific|a BIM]] or [[electrical:12v:b2b|DC-DC charger]] //for banks >300Ah//.   
 + 
 +If not already present, a small switch to [[electrical:12v:alternator#disabling_alternator_charging|disable the combiner]]((same goes for [[electrical:12v:b2b|DC-DC chargers]])) at will is a good idea. 
  
  
electrical/12v/drop-in_lifepo4.1742318863.txt.gz · Last modified: 2025/03/18 13:27 by frater_secessus

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