Battery switch hook up for Tohatsu 50 hp TLDI

[whoopy]

I am adding a second battery so I purchased a battery switch so I could charge each battery using the outboard charging system. Bought one with make-before-break switches and with Alternator Field Disconnect (AFD) thinking the AFD was necessary to protect the charging system when switching from battery 1 thru Both to 2.<br /><br />The switch has lugs for the positive battery cables and two small connectors for a Field wire that connects the alternator to the voltage regulator. The instructions say the AFD cannot be used with alternators having internal voltage regulators. <br /><br />I don't know if the Tohatsu can utilize the AFD.<br />Can I just hook up the postitive battery cables and switch from one battery to another without damaging the charging system or should I be using the alternator field disconnect feature?

 

[Boatist]

Re: Battery switch hook up for Tohatsu 50 hp TLDI

The Alternator field disconnect is great for alternators that have a external Regulator. On a outboard I do not think there is any way to use it.<br /><br />Yes you can hook up one battery to 1 and the second battery to 2 and it will work fine. Just never never turn the switch to off with the motor running or you will need a new alternator. I would not switch at all with the motor running, but that is just me. If it is make before break it will work from 1 to both to 2 but never turn thru off with motor running.<br /><br />For charging two batteries I perfer a Battery isolator, but again that is just me.

 

[whoopy]

Re: Battery switch hook up for Tohatsu 50 hp TLDI

Thanks Boatlist. You verified what I had concluded and pointed me to isolators. <br /><br />I know nothing about battery isolators but think this may be a good time to find out. The cost and inconvenience of a breakdown will surely exceed the cost of whatever it takes to prevent it.<br /><br />Had a sailboat with a diesel (no AFD) and I routinely switched from 1 thru both to 2 with the engine running. I was told to be at idle when switching. If one of the batteries is too weak to start the engine you need to switch when running. I never ran with the switch set on both. Worried that if one battery failed it could take the other one with it.

 

[Boatist]

Re: Battery switch hook up for Tohatsu 50 hp TLDI

To be honest I do not know if you can use a battery isolator either. For you to be able to use it your motor must have a alternator output line to charge the batteries. If it only has a big balck and a big red wire to the battery then do not buy one. This output line normaly about a 10 guage red wire. If the connection is wired inside your motor cover you would have to find the wire and cut it then run it to the isolator input. take the outputs and run them to each side of your battery switch or to each battery.<br /><br />Good parts of a battery isolator. <br />1: If one battery goes bad it will not discharge the other battery like would happen if you used a battery switched set to both. Still the dead battery would still take most of the charge current from the altetnator.<br /><br />2: If the battery you have the switch set to should have a loose cable it will not blow your alternator unless the other battery is also disconnected. Also if someone switches battery switch to off with the motor running your alternator will surrive because the alternator will still see the load of both batteries.<br /><br />I been useing one since 1980 and never had a battery that did not last 6 years. It is really just two big Diodes that allows each battery to charge but not discharge the other battery.<br /><br />The down side<br />1: Since the diode is in serries with your battery and you must forward bias the diode junction you will get from .3 to .7 volts drop to the batteries. I have not been able to messure it on my boat but it should be there. If you are running a gel cell or agm battery this might make a difference.