Wiring hell

[Kyrie]

So just got done building the wiring harness when I got lazy! I decided since I am wiring two 6v batteries in series to have both 6v and 12v options, I would just wire my 12v trailer lights up to my 48 WHMAX. 
I know, ghetto , but the money pit is killing me! So I also have a Signal -stat 900 turn signal switch. The in line fused load wire goes to the ammeter which is 6 volts. The lights and switch are 12v. The signal stat also hooks up to the battery switch. If I need to run 12 volt taillights and can also go 12 through the signals. How do I hook it up? The load for the signal switch should be hooked up to battery (12v) and it is also connected to brake switch. Can I only use one  terminal of brake switch? I thought I would need to power the brake switch from battery but thinking maybe the signal switch connection to battery will also power brake switch. I’ll post a drawing as it sound so confusing!

[Merle Coggins]

You would be better off doing a full 12 volt conversion rather than trying to run 6 volt and 12 volt systems off the same battery bank and charging system. Without a quality Battery Equalizer between the batteries and the alternator/generator your batteries won’t charge equally. One will over charge and have a short life. I’ve seen it happen multiple times when someone connects 12 volt accessories to a single battery of an 24 volt system, which is what is in the machines I work with daily. 

[bach4660]

Just thinking outloud, the 6 volt was a positive chassis ground, but I guess the alternator,starter etc are not chassis ground but cable ground so they could be attached to a 12 volt negative ground??

 

[lostviking]

In order to do what you describe, you would need to add a LOT of circuitry to switch circuits using one voltage, but be switching circuits at another voltage. I can figure out how to do it, because I'm weird like that...but it wasn't easy or something I would have ever done. I just wanted to see if I could. It is frankly a mess. Listen to Merle and just do a 12V conversion. It's not hard, so why create needless and unproductive complication?

[Kyrie]

I wired my 2 6v batteries in series so I can keep all of my front-end electronics&motor 6 volt original and have the option of 12v to power a phone charger. I got lazy and grabbed 12v magnetic trailer lights and am trying to make them work. I have no clue about 12v negative vs 12v positive. So that’s where I’m at….  I’m refurbishing this old truck simply from common sense ? and the original shop manual! 

[Merle Coggins]

There are DC to DC converters available that can give you 12 volts for things like power outlets for charging phones or GPS units. It would be much easier to use one of those than to do what you are trying to do. It looks like your lights are LED. Have you tried them on 6v to see if they work? LED's don't require a lot of voltage to function. 

[Kyrie]

I thought I posted prematurely and was right! I  have the indicator and brake switch on 12v while keeping the rest on 6 volt. Wasn’t hard or costly..just a tad confusing but guess what… victory! It works without any added circuitry nor the expense of replacing generator, coil, starter. Glad I listened  but thanks for trying!!!

Now to wrap all my wires up and into the body clips! ?