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electrical:12v:alternator [2024/01/01 10:27] frater_secessus [TLDR] |
electrical:12v:alternator [2024/03/15 12:27] frater_secessus [combiners] |
===== paralleling different chemistries ===== | ===== paralleling different chemistries ===== |
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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**. |
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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. |
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| **Example** using a flooded starter battery, LiFePO4 house battery, relay, and 14.2v alternator: |
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| * **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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"Split charge relay (SCR)", "split charger", "automatic charge relay (ACR)", "Voltage sensing relay (VSR)", solenoid, relay, etc. | "Split charge relay (SCR)", "split charger", "automatic charge relay (ACR)", "Voltage sensing relay (VSR)", solenoid, relay, etc. |
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Power from the alternator is shared with the house battery by paralleling the two sets of batteries at certain times. This allows the [[electrical:12v:intro|house battery]] to charge but does not allow the house battery to pull power from the starter battery when not combined. | Power from the alternator is shared with the house battery by paralleling the two sets of batteries at certain times. This allows the [[electrical:12v:intro|house battery]] to charge but does not allow the house battery to pull power from the starter battery when not combined. [[https://www.youtube.com/shorts/nHS7aJuJd6c|This short video]] illustrates how it works. |
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==== voltage-sensing relays ==== | ==== voltage-sensing relays ==== |
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[[https://amzn.to/2Ri2jQV|{{ https://images-na.ssl-images-amazon.com/images/I/418qcncjT0L._AC_US218_.jpg|}}]]voltage sensing relays (VSR, also called Automatic Charging Relays or ACR) are solenoids with a bit of extra logic to know when to connect/disconnect. The VSR does not get trigger voltage from the fuse panel but rather reads the voltages of one((VSR)) or both((dVSR - d is for //dual//)) batteries to know when to switch on. \\ This kind of isolator may have a "combine" override function to enable [[electrical:12v:self-jumpstarting|self-jumpstarting]]. | [[https://amzn.to/2Ri2jQV|{{ https://images-na.ssl-images-amazon.com/images/I/418qcncjT0L._AC_US218_.jpg|}}]]voltage sensing relays (VSR, also called Automatic Charging Relays or ACR) are combiners with a bit of extra logic to know when to connect/disconnect. The VSR does not get trigger voltage from the fuse panel but rather reads the voltages of one((VSR)) or both((dVSR - d is for //dual//)) batteries to know when to switch on. \\ This kind of isolator may have a "combine" override function to enable [[electrical:12v:self-jumpstarting|self-jumpstarting]]. |
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> in its simplest form, all an ACR really does is parallel batteries when charging is present and un-parallel batteries when there is no charging present. It does this automatically with no human forgetfulness.((https://marinehowto.com/automatic-charging-relays/)) | > in its simplest form, all an ACR really does is parallel batteries when charging is present and un-parallel batteries when there is no charging present. It does this automatically with no human forgetfulness.((https://marinehowto.com/automatic-charging-relays/)) |