Txt aux. Battery help

[stellix]

I added a 12 volt battery to run my lights and winch .The factory wiring harness had a green wire going to the pos. side of one 6 volt battery and a black wire going to the neg. side of the next battery to make 12 volts.I thought that all i needed to do was connect those two wires to my 12 volt aux. battery.I did just that and the lights work fine,the problem is that i lost power to my state of charge meter and i noticed the green light on my Alltrax controller stays on even with the switch off.I unhooked the 12 volt battery and hooked up the green and black wires back to the pair of 6 volt batteries like it was and the state of charge meter and controller light are back to normal.Does anybody know what else is connected to the green and black wires hooked to the pair of batteries? I need to figure out how to seperate the light wires and switch,it has the factory key switch with a position for the lights.Do i have to use a seperate switch to use an aux. battery?

[yurtle]

I don't know, but try to disconnect just the green wire and see if everything works. If not, reconnect and disconnect the other.

Maybe you just need one of the two for your stuff to work.

The controller has me stumped though.

[JohnnieB]

Your SoC meter originally measured between B+ and B- on the 36V battery pack.
When you moved the Black wire from the 36V pack to the 12V battery, it lost B- from the 36V pack.
Run a wire from SoC meter negative terminal to negative terminal on 36V pack.

Personally, I would replace the LED Bar Graph "Guess-O-Meter" with a DVM type.

To figure out why Alltrax controller is staying on, I need to know which controller and what cart it is installed in.

[stellix]

Its an Alltrax 400 DcX and the cart is a PDS

[JohnnieB]

Does the controller turn off when the Run/Tow switch is in Tow?
If so, it might be wired for Anti-roll Away, but just moving the 12V accessory wiring to a separate 12V battery rather than tapping into the 36V pack shouldn't have effected whether it stays on with Key off or not

Short of having the cart in front of me and tracing out the wiring, I have no idea why is stays on now and didn't before.

[stellix]

It does go off when i flip the switch to the tow position. The ground for the state of charge meter and the lights must be connected. I dont understand why since one is 12 volt and the other is 36 volt

[JohnnieB]

Originally Posted by stellix

1. It does go off when i flip the switch to the tow position.
2. The ground for the state of charge meter and the lights must be connected. I dont understand why since one is 12 volt and the other is 36 volt

1. Maybe someone more familiar with AllTrax DCX controllers installed in a PDS can answer this one. I can find schematics for the controller connected to a Sepex motor and for a stock PDS, but haven't seen a schematic for the interface adapter. Still, I can't imagine how moving accessories to a separate 12V battery can effect when the controller turns on.

2. Actually there isn't a "Ground", or at least the cart frame is not used as a common return path for anything.
Specifically, every circuit has two wires, one connecting to the battery's positive pole and one connected to the battery's negative pole.

Unfortunately, with the stock wiring harness, both the 12V accessories and the 36V SoC meter use the same wire as the return path to the negative pole of the battery pack.

To get both circuits to work completely separate from each other, a return path must now be provided to the most negative post of the battery-pack and and a separate one to the negative pole of the 12V accessory battery.
Otherwise, the most negative post of the battery pack will have to be connected to the negative post of the 12V accessory battery.

[yurtle]

Just curious, do the two circuits truly need to be independent wrt negative?

What's wrong with sharing the negative?

[JohnnieB]

Originally Posted by yurtle

Just curious, do the two circuits truly need to be independent wrt negative?

What's wrong with sharing the negative?

Nothing is electrically wrong with sharing the negative, that is what the stock wiring harness does.

However, there is the potential of shorting +36V to the +12V when the negative return paths are common.
IE: The close proximity of 12V and 36V terminal on the key switch.

Using separate wires for the return paths eliminates that possibility.

------------
Added:
When using a common return for multiple powers sources, some interaction can occur if the common conductor is too small for the combined current.
Don't ask how I know.

[stellix]

That is exactly what i just found,everything shares the same neg.wire going to the b- on the 36 volt pack.if i unplug the neg. Wire on the back of the state of charge meter the meter turns off and the green led on the controller comes on even with the switch turned off.Right now i just connected the b- on the 36 volt pack and the neg. On the 12 volt battery and everything works good.I think i'll run a seperate wire from the meter to the pack just to be safe.