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electrical:12v:directcharginglfp [2024/03/20 12:05]
frater_secessus [assessing your own setup for direct alternator charging] 		electrical:12v:directcharginglfp [2024/04/04 11:51] (current)
frater_secessus [reasons NOT to attempt direct charging] temp
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   * you have a **small or already-overloaded alternator**   * you have a **small or already-overloaded alternator**
   * you **already own a DC-DC**    * you **already own a DC-DC** 
 +  * your BMS has no low temp charging disconnect and you have no desire to work around that((to be fair, this also rules out DC-DC that lack low-temp disconnect))
   * you **want predictable charging rates**, like 40A over the next hour.  DC-DC will provide this((barring interference from big chassis loads, BMS protections, high ambients, etc));  isolator charging starts out high and drops as battery voltage rises.  You might learn its behavior over time, but it will never be as easy as "40A for 1.5 hours = 60Ah".    * you **want predictable charging rates**, like 40A over the next hour.  DC-DC will provide this((barring interference from big chassis loads, BMS protections, high ambients, etc));  isolator charging starts out high and drops as battery voltage rises.  You might learn its behavior over time, but it will never be as easy as "40A for 1.5 hours = 60Ah". 
   * you want **stable charging rates** regardless of state of charge((acceptance will taper in Absorption if present))     * you want **stable charging rates** regardless of state of charge((acceptance will taper in Absorption if present))  
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   * Only alternator charge while driving ([[rv:idling|no idling]] except for brief preliminary test).     * Only alternator charge while driving ([[rv:idling|no idling]] except for brief preliminary test).  
   * Pay attention while charging from alternator to keep from overcharging the Li or holding for long periods at high [[electrical:depth_of_discharge|states of charge]]. You may want [[electrical:12v:alternator#disabling_alternator_charging|a manual disconnect]] or [[electrical:12v:alternator_charging_hvd|HVD]] to shut off alternator charging due to excess voltage or if the bank is already charged.  These can be added on the D+ wire (ignition triggered) or electronics ground wire (VSR, solenoid, or voltage-triggered DC-DC)   * Pay attention while charging from alternator to keep from overcharging the Li or holding for long periods at high [[electrical:depth_of_discharge|states of charge]]. You may want [[electrical:12v:alternator#disabling_alternator_charging|a manual disconnect]] or [[electrical:12v:alternator_charging_hvd|HVD]] to shut off alternator charging due to excess voltage or if the bank is already charged.  These can be added on the D+ wire (ignition triggered) or electronics ground wire (VSR, solenoid, or voltage-triggered DC-DC)
-  * Fuse the wiring from the chassis so the bank cannot pull more than you specify +  * if current is excessive but you want to direct-charge, you can tweak acceptance with resistance or voltage as seen elsewhere in this article
-  * if current is higher than you want consider adding resistance to the circuit+
  
 ===== the parts list ===== ===== the parts list =====
electrical/12v/directcharginglfp.1710950739.txt.gz · Last modified: 2024/03/20 12:05 by frater_secessus

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