[waycamp]

can anyone explain the how the battery isolators on a 2900 open work?.    Under the stairway I have two isolators, assume one for each engine.  They all seem to be cabled together.    The alternator on the starboard side isnt outputing a charge,per the analog gauge. I  Had the altenator tested and it is good,   When both engines are running it  seems at least one alternator is chargng both battery banks.   can one of the isolators go bad?   if this sounds confusing it is because I am confused.  Any help would be appreciated

[jclark003]

Isolators are diodes that allow one charge source (ex: alternator) to charge two (or in some cases more) battery banks while allowing each bank to discharge a different rates. An example would be one alternator feeding an isolator that feeds a house battery bank and a separate generator battery.

Isolators can fail especially if the charge rate exceeds to maximum rated current. Otherwise they are pretty durable components

If the isolator is working properly the input and output voltages should be the same when the charge source is in operation (example >13v when alternator is charging)

There are numerous ways 2 isolators could be wired so it is quite difficult to give you additional advice. You can reach out to Tiara for a wiring diagram, assuming it is a factory configuration. Otherwise unless another member is aware of how these are wired you will need to trace the wires to their source and make your own wiring diagram. Or you could try turning on each charge source (engines, chargers, generator) one at a time while putting a meter on each isolator input. Once you know which charge source is connected to the isolator you would meter each battery bank looking for the same charge voltage. Sounds complicated but it really isn’t once you understand how they work. Make yourself a schematic so you don’t forget.

Standard caution: recommend you disconnect batteries and disable any chargers when attempting to disconnect or service any of the ships electrical systems/wires.