Headlights work, no wire back to negative

[battleboro]

In my CC DS (6 - 8Vs), I have headlights and tail lights that work, but cannot find the tie back to negative. There are 3 wires, I believe to be dedicated to the lights only, coming off the positive post of 2 batteries, but nothing coming off the negative posts. The lights have 2 wires in use with the exception of the parking lights that only have 1 wire. Is it safe to say that someone terminated the negative to the cart frame somewhere?

I have not taken a good look underneath yet, but from what I can tell there are 6 bulbs running off of 2, 8v batteries; 2 headlights, 2 parking lights and 2 tail lights. Meter readings on a headlight and a tail light yielded only 7.4 volts each; yes, the lights are dim (halogen). So, something is going on there.

[Mooncarter]

Unhook everything and start from scratch. It sounds like somebody somehow grounded them to the frame. Get a 48 - 12 volt reducer and wire it so it can draw evenly across the pack. This would be a good time to install LED lights that draw very little current.

I wouldn't even worry about trying to figure out what they did.

Doing this will save your batteries if they are not already ruined. You also have a potentially dangerous situation.

[battleboro]

Originally Posted by battleboro

There are 3 wires, I believe to be dedicated to the lights only, coming off the positive post of 2 batteries.

I found the problem. I identified the correct wires that should have been going to a negative post. I am now getting the expected 16v (8v * 2) at a bulb and they have never been brighter.

After watching this video, I was able to determine what my wires were doing even though our wiring was not exactly the same. Other videos I found assumed a kit, complete with wiring harnesses.
https://www.youtube.com/watch?v=6ZL23UnB5cM

I guess someone was having an "off" day and simply connected the 3 wires to 2 positive posts instead of pos and neg in a series. The installation looks factory or modified by a professional (nicely done). It has been this way for 7-8 years. This probably explains the brown clay-like substance (lead?) coming from the bottom of a positive post. Unlike any corrosion I have ever seen. The battery is probably trashed.

Volt reducer on order. This case is closed.

[Mooncarter]

The lights can't work without a negative /ground coming from somewhere.

[battleboro]

Originally Posted by Mooncarter

The lights can't work without a negative /ground coming from somewhere.

That's what I thought, but chalked up the odd situation to the differences between carts & cars and my limited electrical knowledge.

I'll be putting it up on jack stands soon and will give it a proper "once over", but I couldn't rest without knowing why all the wires were going to positive posts.

[Mooncarter]

Be careful under there these things are heavy.

Should you need help with the reducer there's a lot of help in here.

Good luck.

[WalterM6]

The common negative wires connect to the B- terminal. This way they are effectively running through the hole in the OBC .

[Mooncarter]

Originally Posted by WalterM6

The common negative wires connect to the B- terminal. This way they are effectively running through the hole in the OBC .

This is true if he has a working OBC, and a good very point Walter.

The way I understood the situation, he has no negative wire at the lights, only 3 positive wires.

What do you have battleboro?

[Fairtax4me]

Originally Posted by battleboro

That's what I thought, but chalked up the odd situation to the differences between carts & cars and my limited electrical knowledge.

I'll be putting it up on jack stands soon and will give it a proper "once over", but I couldn't rest without knowing why all the wires were going to positive posts.

You have to keep in mind that voltage doesn't care about the polarity of the terminal. On batteries connected in series the positive post of a second, third, etc. battery is equal in Potential to the negative post of the battery ahead of it. The voltage is the same at each end of the connecting cable, so any connection made there can be considered a negative regardless if it is connected to a positive or negative post. In the same manner any terminal in the center of the pack can also be considered a positive as long as the negative connection is made at some point further down the line.
Electrical potential moves from high to low, That is to say, if the voltage on one side of the completed circuit is higher than the other side, current will flow in the circuit, and as long as there is sufficient current flow the load (lights) will work.

You can have a supply wire (positive) connected to the negative terminal of battery #1, and the negative wire connected to positive terminal on battery #3 and you will only measure an 8V difference, but the lights will still work because the potential on the supply side is still higher than on the negative side. This works because the Cable between battery 1 and 2 is the same potential (voltage) no matter which end you connect to. The negative of battery 1, is electrically the same as the positive of battery 2, because they are connected to each other via cable. The positive of battery 3 is the same as the negative of battery 2. In essence the connections are made at the positive and negative of battery 2, thus you will only get 8V from those connections.

And the same applies for the cables between subsequent batteries in the series.

Making positive connections to positive terminals helps to avoid confusion, but it's not necessary for the circuit to work. There's more than one way to ride a unicorn.

[battleboro]

Originally Posted by Mooncarter

This is true if he has a working OBC, and a good very point Walter.

The way I understood the situation, he has no negative wire at the lights, only 3 positive wires.

What do you have battleboro?

=========================

Fairtax4me...

You can have a supply wire (positive) connected to the negative terminal of battery #1, and the negative wire connected to positive terminal on battery #3 and you will only measure an 8V difference, but the lights will still work because the potential on the supply side is still higher than on the negative side.

Mooncarter, WalterM6, I do have an OBC and was planning to connect the negative of my soon to be installed volt reducer to the B- terminal, as described on a popular volt reducer install thread.

Fairtax4me, this explains why I was only getting 8v at the 12v lights. And when I completed the series of 2, 8v batteries by moving one wire from pos to neg, the lights got brighter (16v instead of only 8v). Thanks for the details. I like to fix AND understand.

Mooncarter, I'm still going to look the cart over for any negative termination to the frame. I read the thread where this guy terminated the negative of his lights to the aluminum boat. I don't want my cart frame turning to dust.

Thanks for everyone's help.