Adding Second Battery Need Long Cables

I’m going to add a second battery and selector switch. The first is on the port side and the new one will be on the starboard. What do I use for these long cables (maybe 7 feet) from one side of the boat to the other. I assume I need to make them. Where do I buy the materials? What gauge wire? Does it need to be special for marine use?

Re: Adding Second Battery Need Long Cables

Electrics topic.

Re: Adding Second Battery Need Long Cables

They need to be at least the same guage as your current cables. And yes, marine versions are preferable to auto versions of the same although they are likely to be more expensive. <br /><br />Westmarine sells 25' versions in 2 and 4 guage. 2 guage seems to be $58 and 4 guage $78. They may sell the by the feet in the store which would be preferable as you would need to buy black and red ones. YOu can find more info at: http://www.westmarine.com/webapp/wc...=10001&classNum=123&subdeptNum=120&storeNum=9 <br /><br />Of course, westmarine is usually more expensive so you may want to check boatersworld. Their online site unfortunately, does not show the above cables.<br /><br />Termination may be a bit tricky though. Marine stores may be able to help with that or you may have to buy extra heavy duty crimping tools.<br /><br />Finally, be extra careful. You are playing with suer high current sources here. A simple dropped rench may cause a fire or worse.<br /><br />Amir

Re: Adding Second Battery Need Long Cables

Not sure its clear to me how to hook these up. I have one engine 1988 Yamaha 130. Do I need to tamper with alternator/regular wires at all, diagram shows I do? If I plan not to move switch with engine running is there any need for this? Do I connect ground to ground on the two batteries? How many wires are coming from the engine I need to deal with here?

Re: Adding Second Battery Need Long Cables

Positive cable from starboard battery to switch position #1; positive cable from port battery to switch position #2; positive cable from engine to switch position "C" (plus any other power wires you want only switch on hot); negative engine cable to either battery negative; negative cable from battery negative to battery negative; negative accessory lead to either battery negative. No other mods are required as long as you don't hit "OFF" with the engine running; it's OK to move between 1/2/both.<br /><br />Anything that you wantto always be hot (like an auto bilge pump) should be wired to switch position #1 or "2, or directly to a battery positive.

Re: Adding Second Battery Need Long Cables

Okay, that seems pretty easy. So I don't need to be concerned with the alternator or regulator wires that are shown tied into the two small screws on the rotary switch instructions, is that right?<br /><br />I think I have six wires coming from the engine.<br /><br />Two 6 AWG +/- for starter<br />Two small +/- for alternator<br />Two small +/- for trim & tilt<br /><br />Does that sound right?<br /><br />Right now attached to my battery are several negative wires and only two positive. I assume the positives are, 1 for starter, 1 for alternator, right ? Just leave the alternator tied to its original spot?

Re: Adding Second Battery Need Long Cables

I would think the positive wire from the alternator needs to go to feed with starter wire to enable both batteries to charge, right?

Re: Adding Second Battery Need Long Cables

I would put all positive leads on the switch, except maybe an auto bilge pump; I want the entire electrical system shut down when the switch is "off", but that's just me.<br /><br />That being said, what ever is connected directly to a battery (or terminal 1/2 on the switch) will only operate off that battery. What ever is connected to the "common" switch terminal will operate on which ever battery is selected by the switch. Assuming the motor positive lead is connected to "common", the motor will charge which ever battery is selected by the switch (or both).<br /><br />The alternator wires are designed to disconnect the "field" before the switch hits the "off" position, which saves it from damage. It should be connected as indicated by the two battery-one engine switch diagram. Alternately (no pun), don't ever place the switch to "off" with the motor running.

Re: Adding Second Battery Need Long Cables

Okay, think I got it now - your explanation seems to make sense. I didn't know there was separate leads coming from the alternator to the battery. I thought for some reason the two big cables did it all. <br /><br />So the pos starter cable and pos alt cable mount to the "C" terminal? B1 pos to B1, B2 pos to B2, tie all the negs together .....<br /><br />Hope I don't see smoke

Re: Adding Second Battery Need Long Cables

Dont let the smoke get out of the wire.<br />If this happens the wire is stuffed coz you cant get the smoke back in.<br /><br />Take care when doing this and you'll be OK.<br /><br />Peter

Re: Adding Second Battery Need Long Cables

I had new battery cables made for me at a Johnson dealership. They cut, crimped, etc. for about $40 for the pair.<br />Stalker

Re: Adding Second Battery Need Long Cables

Thanks, My shop said they would do the same.