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battery isolator-gctid759276

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    Your caution is well placed. I don't have an issue with that. My point is that if the "good" battery is supplying some of the current that the "weak" battery is sinking, because it sinks in more current than what the alternator can provide, that is a scenario under which the ACR should not engage. Consider the following:

    Alternator is providing, say, 25 amps and the "weak" battery is sinking, say, 30 amps" so that the " good" battery is being forced to provide the additional 5 amps to make up what the "weak" battery needs. At that point assume we disabled the ACR and waited for 5 minutes and then "enabled" the ACR so it will operate in automatic mode. Whichever battery is connected to the Alternator must have its output voltage at above 13.5 v so the ACR shall connect the two batteries. If this is the "good" battery, then the "weak" battery must remain above 12.75 v for the ACR to remain engaged. This condition would not result in all current from the altenator being sucked in by the "weak" battery.

    I think your situation was different. If you manually (via the MBSS) connect the two batteries, having no intelligence, the stronger battery will indeed provide current to the weak battery. ACR uses continuous sampling of the two batteries to detemine when to connect/disconnect. Still, it is good advice not to operate a strong battery in parallel with a weak battery.

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