

If an alternator was connected directly to the batteries, then for it to pass a Boat Safety Scheme examination it would be necessary to fit a suitable fuse in the circuit and also to provide written evidence from the manufacturer of the alternator supporting the decision to by pass the main Isolator.

Richard you are very wrong and should not be giving advice like this until you better understand the requirements of wiring on boats which come under the requirements of the BSS. My question is simple, is this right? Or should the 2 pole isolator, actually be a 3 pole? However this means that when the switch is turned off, the alternator is still connected to the batteries, so if the engine runs, it is still charging, and if the engine is not running, there is still a 12v feed to the alternator. The alternator and battery both go to one pole, and the load goes to the other pole. The engine has 2 alternators, one for the engine battery bank, and one for the domestic.Įach circuit (engine and domestic) has a battery isolator switch with 2 poles, so effectively te switch either makes, or breaks the circuit between the 2 poles. I have noticed however that the 2 battery isolator switches do not fully isolate the batteries. This has had the desired effect, and the electricity reliability, especially the 240vAC is significantly better. He has changed from 3 x 110Ah Batteries, to 3 x 225Ah batteries. Consult you engine wiring diagram for the proper connections if you have an I/O or inboard engine.I have recently helped my dad replace his domestic battery bank. Run a new 10-gauge wire from the alternator output wire of the engine to the battery isolator input terminal. Check your motor’s wiring diagram to do this properly. If you have an outboard, the alternator wire must be removed from the positive battery connection at the motor end. Connect two 10 gauge wires from the battery isolator to each positive battery terminal. Attach the battery isolator to an inside wall of the boat with self-tapping screws, or if you can reach behind the panel, you can thru bolt the unit. Mount the battery isolator, which is about half the size of a normal battery, in a dry area somewhat close to the battery bank. To select the proper battery isolator, check with your local dealer so that he can advise you of the proper model for your application. This means you will never be suprized with a dead battery.
#Battery isolator switch wiring diagram install
To make sure that both batteries are fully charged, install a low cost battery isolator.Ī battery isolator allows each battery in the boat to receive a full charge even if it is not the battery being selected by the battery switch. This could be a problem if one of the batteries is low or completely dead, as the dead battery will draw a charge from the charged battery and may drain the charged battery so that the motor cannot be started. Turning the battery switch to “both” connects the two batteries together. If you have a dual battery system in your boat, you may have noticed that only the battery selected by the battery switch is being charged while the engine is running.
