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opinion:frater_secessus:agm2lifepo4

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opinion:frater_secessus:agm2lifepo4 [2025/04/22 18:13]
frater_secessus [Upgrading a lead-chemistry house bank to LiFePO4] 		opinion:frater_secessus:agm2lifepo4 [2025/07/05 01:34] (current)
frater_secessus [shore power charging] high 14s
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 Maybe. Probably.  Here is a cheat sheet to the main issues: Maybe. Probably.  Here is a cheat sheet to the main issues:
  
-  - what the LiFePO4 battery needs((either manufacturer specs or a deeper understanding of the chemistry))+  - what the LiFePO4 battery //needs//((either manufacturer specs or a deeper understanding of the chemistry))
     * moderate //charging voltage//((≤14.4v.  LFP will charge to 100% SoC at voltages as low as 13.6v))     * moderate //charging voltage//((≤14.4v.  LFP will charge to 100% SoC at voltages as low as 13.6v))
     * relatively low //float voltages//((≤13.4v)), or [[electrical:solar:status#setups_with_no_float|no float at all]]     * relatively low //float voltages//((≤13.4v)), or [[electrical:solar:status#setups_with_no_float|no float at all]]
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     * [[electrical:converter|shore power charging]] (voltage, output rating, stages if any)     * [[electrical:converter|shore power charging]] (voltage, output rating, stages if any)
  
-If the existing system cannot be configured to meet LFP's needs within [[electrical:12v:alternator_details#current|the  alternator's comfort zone]] then you are looking at replacing some components. For more specific guidance please share details about your setup, use case, budget, and priorities. +If the existing system cannot be configured to meet LFP's needs then you are looking at replacing some components. For more specific guidance please share details about your setup, use case, budget, and priorities. 
  
-Note:  **undercharging lithium is not an issue** unless you are running out of power. This is a radical change from lead-battery charging. +Note:  **undercharging lithium is not an issue** unless you are running out of power. It does not need and does not even like to be charged to 100%,  This is a radical change from lead-battery charging. 
  
  
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 ===== shore power charging ===== ===== shore power charging =====
  
-Shore power charging is relatively rare for vandwellers and has many factors feeding into it.  +Shore power charging is relatively rare for vandwellers and boondocking RVers, but very common for RVers who have frequent access to "pedestal power".  The use case will determine which way to go with shore power charging.
  
  
-IF **other forms of shore power charging are available** or **shore power charging will last at least overnight** the [[electrical:converter|shore power charger]] can be a simple, inexpensive, single-stage charger set to a relatively low voltage (13.5v - 13.6v?)  This will allow near full charge and load support without overcharging.  Lower set voltages like 13.2v - 13.4v will support the battery from depletion but won't charge completely.  If there is solar present that will also contribute. +IF **other forms of shore power charging are available** or **shore power charging will last at least overnight** the [[electrical:converter|shore power charger]] can be a simple, inexpensive, single-stage charger set to a relatively low voltage (13.5v - 13.6v?).((converter output voltages can often be adjusted with built-in switches or "pots" (potentiometers).  Consult the manual or online documentation))    This will allow near full charge and load support without overcharging.  Lower set voltages like 13.2v - 13.4v will support the battery from depletion but won't charge completely.((remember, there is no requirement to charge LFP to 100%))  If there is solar present that will also contribute. 
  
-If **shore power charging is the only source of charging** or if **time on the charger is limited** then a more aggressive, expensive, higher-capacity multistage charger may be warranted.  +If **shore power charging is the only source of charging** or if **time on the charger is limited** then a more aggressive, expensive, higher-capacity multistage converter/charger may be warranted.   
 + 
 +If the converter is a **multi-stage charger hardcoded to Absorp in the high 14s** then a less aggressive converter will be required unless you plan to manually intervene, cutting off charging in the "upper knee".
  
 If the van will **be on shore power for an extended period** (days, weeks, months) then a small single-stage converter charger set to quite low voltage (13.2v?) would hold the battery at middling states of charge.  It only needs to be a bit bigger than the expected loads so gradual charging can occur.   If the van will **be on shore power for an extended period** (days, weeks, months) then a small single-stage converter charger set to quite low voltage (13.2v?) would hold the battery at middling states of charge.  It only needs to be a bit bigger than the expected loads so gradual charging can occur.  
opinion/frater_secessus/agm2lifepo4.1745345596.txt.gz · Last modified: 2025/04/22 18:13 by frater_secessus

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