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--- electrical:12v:alternator [2024/02/01 19:21]
frater_secessus [voltage-sensing relays]
+++ electrical:12v:alternator [2024/03/02 19:15]
frater_secessus [paralleling different chemistries]
@@ Line 152: / Line 152: @@
 ===== paralleling different chemistries =====
-It is often said that one cannot parallel batteries of different chemistries.  The problem is paralleling batteries with different resting voltages //when the batteries are not being charged//.  The isolator setup is specifically designed to isolate the batteries when there is no charging.((DC-DC chargers and diode isolators keep them isolated 100% of the time, even when charging is present))
+It is often said that one cannot parallel batteries of different chemistries.  This is not so.  The problem would be keeping batteries with different resting voltages connected //after charging is removed//.  If they were left connected the higher-voltage batt would discharge into the lower-voltage batt.  Note: **an isolator setup is specifically designed to keep this from happening**.
-There may be an issue of the alternator having improper voltage for charging one or the other but that has nothing to do with the isolator.
+As long as the alternator voltage is acceptable to both battery chemistries they can be paralleled during charging.
+**Example** using a flooded starter battery, LiFePO4 house battery, relay, and 14.2v alternator:
+  * **charging**:  both batteries will charge to 14.2v (given enough time)
+  * **no charging**:  relay separates ("isolates") the batteries.  Starter batt rests at 12.7v and lithium at 13.5v.

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