Need electrical/wiring help for Supra w/ 3 batteries+perko

[wotan2525]

Hey guys -- last summer I picked up an 88 Supra Saltare that is in really good shape. I've had nothing but problems with the battery/charging system though, so I'm going to rewire it.

I need some idea on how to wire 3 batteries with a perko switch. The guy I purchased it from said that they way it should work is that 1 battery should always be on reserve for starting, and the other 2 can be isolated to run the stereo and that way if they run down, you can flip the perko and still start the boat. The problem is that no matter what I do -- all the batteries go dead either on the water, or just sitting with the switch set to off.

So here's what I need.... an idea how they SHOULD be wired. I'd also like to know how I can test the alternator, and how I can test to see if anything is drawing current with the switch off. There are tons of connections, and I'm thinking there has to be way to just check positive wires to see what is drawing.

Here's a picture..... keep in mind that this is only with 2 batteries in the boat -- it gives you an idea of what a disaster I'm dealing with.

[wotan2525]

No responses -- took out the alternator and took it into the shop yesterday. The guy said it worked perfectly but had been wired wrong, and claims thats where a lot of my problem is coming from. He also indicated that I should get a bigger one, and I totally agree.

Nobody has any idea how I should wire a 3-battery setup with a perko switch? How about, what kind of distribution block can I get for all those wires so that I just have 1+, 2+, 3+ and then 1-, 2-,3-

Thanks again.

[wesgardner]

Hey wotan2525,

You should wire your Perko so #1 is just "Start" and #2 is "House". You'll have 1 battery for starting and two wired in parallel for "house".

Make sure ALL batteries are good - have them checked...then you'll need to UNHOOK stuff til you find the "load"...or you can put a test light in-line, when the light's on, there's current...

I would think if your batteries are going down, there's stuff hooked up to them that is NOT running thru the Perko switch (other than the memory wire to maintain your stereo presets - draws milliamps...)

Also make sure the mating surfaces where your alternator and your starter are physically bolts to the motor are CLEAN - this is the other half of the electrical "equation" - the negative side...

Another suggestion - DRAW a wiring diagram....

Wes

[wotan2525]

Wes --

Thanks for your help.... yesterday we pretty much just ripped all the wires out and started from scratch. Did exactly what you said and everything seemed to work perfectly... 2 questions though. All the batteries are very new -- but my starting battery is showing like 15+v on the charger, I've never seen anything like it. Any ideas?

Also -- we were testing stuff out and we flipped the switch from 1-all-2 and it fried my cd-deck. Any idea why this would happen?

Thanks - Rob

[Styk33]

15V is a bit high, are you sure your gauge is right?

Frying your deck, are you sure you wired up the batteries paralel?

Remember, if you have the perko on #1 all the time when the boat is running, you will not be charging your #2 battery.

Do you have a pic of how you wired it all up?

[chavez]

wotan2525, 1 word: Isolator.

[wotan2525]

Here's my little wiring diagram I just made.... and basically when I hook up the charger, it starts counting up from like 11v, 30 seconds later it hits 15.6v and the charger like goes into protection mode or something, blinks, and then starts over. It's telling me that the battery has 80% juice, but I'm worried about the voltage.

The other batteries show like 12.6, and the charger works perfectly on them, even when they are wired in parrellel. Also, when I turn the key with the hot battery hooked up to the charger and the perko on that batt, I get a loud humming from under the dash.

Rob