Does a battery selector switch only affect which battery is being charged by the alternator or does it also regulate which battery is being drawn from? Bank is run in parallel.
Battery Selector switch
- Thread starter chelsabella
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Alternator charging yes, battery charger depends
The selector switch controls which battery is drawn from or charged to. So when the motor is on you should switch to "both". The battery charger may or may not run through the selector switch. You can tell by looking at the battery terminals. If there is a cable from the battery charger to + terminal on one battery in each bank then the selector switch has been bypasssed and it does not matter which setting it is in when shore power charging the batteries. If there is no extra cable coming from the battery charger then the selector switch controls the bank that gets charged while using shore power.
The selector switch controls which battery is drawn from or charged to. So when the motor is on you should switch to "both". The battery charger may or may not run through the selector switch. You can tell by looking at the battery terminals. If there is a cable from the battery charger to + terminal on one battery in each bank then the selector switch has been bypasssed and it does not matter which setting it is in when shore power charging the batteries. If there is no extra cable coming from the battery charger then the selector switch controls the bank that gets charged while using shore power.
Consider by passing the switch
Another way is to wire the alternator directly to the house bank and then use a combiner to charge the starting battery. This ensures that the alternator is always connected to a battery and that the house batteries receive a full charge before charging the starter battery. Of course, the starter battery could be charged first - it is your choice.
Another way is to wire the alternator directly to the house bank and then use a combiner to charge the starting battery. This ensures that the alternator is always connected to a battery and that the house batteries receive a full charge before charging the starter battery. Of course, the starter battery could be charged first - it is your choice.
Factory set up
The way my boat came from Catalina was that the selector controled which battery was being drawed down and charged by the alternator. The on board battery charger charges both batteries when flipped on.
The way my boat came from Catalina was that the selector controled which battery was being drawed down and charged by the alternator. The on board battery charger charges both batteries when flipped on.
The way Bill has described his factory set up
is the conventional installation. Now before doing any modifications you should determine what is your primay charging source. If it is a shorepower inboard battery charger producing juice to both batteries as needed you will probably require no modifications. If you are out on a mooring and require alternator charging to top off your batteries you may consider the installation of a combiner to have both batteries receive charge from the alternator while keeping them separated when not charging. There is a practical principle regarding the battery switch; "only use the "BOTH" setting for a short period of time to provide an emergency boost to start the engine" Consider that 1) two batteries connected together will only charge to the capacity of the weakest one 2) a bad battery will draw down and may damage a good one 3) By human error an applicartion may be inadvertedly left on, like refrigeration, and it will result in two discharged batteries. The object is to have adequate power for our needs while maintaining an adequate reserve to start the engine. Always keep the switch in "1" or "2" using one bank for house and the other as a reserve for starting the engine. This is a fail safe procedure for a two bank battery system. Check the archives for information on larger and more complex systems.
is the conventional installation. Now before doing any modifications you should determine what is your primay charging source. If it is a shorepower inboard battery charger producing juice to both batteries as needed you will probably require no modifications. If you are out on a mooring and require alternator charging to top off your batteries you may consider the installation of a combiner to have both batteries receive charge from the alternator while keeping them separated when not charging. There is a practical principle regarding the battery switch; "only use the "BOTH" setting for a short period of time to provide an emergency boost to start the engine" Consider that 1) two batteries connected together will only charge to the capacity of the weakest one 2) a bad battery will draw down and may damage a good one 3) By human error an applicartion may be inadvertedly left on, like refrigeration, and it will result in two discharged batteries. The object is to have adequate power for our needs while maintaining an adequate reserve to start the engine. Always keep the switch in "1" or "2" using one bank for house and the other as a reserve for starting the engine. This is a fail safe procedure for a two bank battery system. Check the archives for information on larger and more complex systems.
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