Battery Replacement

[Don W.]

Bought our little Casita about two years ago. I have had to work and replace some things but this was weird.

The battery has not been holding a charge much so I decided to get a new one.

Took it to Batteries Plus and when they tested it, The Polarity had reversed! The guy said he had only seen it one time before, when a battery gets soooooo dead it reverses polarity.

Also, it was a Marine Starter, not a deep cycle.

So needless to say I have a nice new Deep cycle battery

One other thing, the Tech questioned how the cables were hooked up. White and Green wires to the Negative, and Black wire to the positive. Said that might have added too the battery troubles.

I called casita and they verified the connections and told me to connect the white and Green to the negative.

Anyone else ever see this? Slowly and surely I am getting my casita up to Mint condition from the previous owner.

[Raz]

With autos black is usually negative. With trailers it is usually positive. I have no idea where that standard originated. That's probably why the tech said what he did. Casita built it. They know best.

I have seen polarity reversal with NiCads but never a lead acid battery. Batteries are made of two chemical reactions. As they occur the compounds change, hence different half cell potentials (voltage). A chemist can explain it far better than I can. Raz

[Ron in BC]

Polarity reversal in batteries used to be quite common in the "old" days. And I'm really dating myself. When British cars used to be much more common it was not unusual for the battery to be reversed since they used positive ground and North Americans sometimes ended up reversing the polarity when installing a new battery. Everything in the car worked fairly well except it would cause ignition problems. I remember turning on my headlights and waiting for hours to kill the battery so that I could recharge the battery and install it correctly.

I don't know about the "got so dead it reversed polarity" theory but I'd make sure sure that the polarity of the wires in question is correct.

I'm aware of the many different standards domestically and internationally to color code wires but I have my own standard. All wires that are negative, no matter what their color, get a black band of electrical tape at either end. Positive wires get a red band. Works for me

Ron

[cpaharley2008]

I always verify any connection with my multimeter, regardless of wire color.

[Thomas G.]

Originally Posted by Ron in BC

...........
I'm aware of the many different standards domestically and internationally to color code wires but I have my own standard. All wires that are negative, no matter what their color, get a black band of electrical tape at either end. Positive wires get a red band. Works for me

Ron

Good idea. I do something similar but with shrink tape.

[Bob Miller]

An inexpensive battery monitor, like a Voltminder (voltminder.com) will help prevent severe discharge and battery damage. The Voltminder not only has a digital display, it also has settable alarms that will warn you when you are getting down to the 50% charge level where permanent battery damage starts to occur.

[Perry J]

Disconnect the gerrn wire and see what happens.
I think your green is the actual ground wire for your 110v system.
John

[Casita Greg]

Casita Battery Wiring:

White (12vdc Return leg) & Green (Bonding wire) to battery NEG. (-)
Black (12vdc Power) wire to battery POS.(+)

[Bob Miller]

As indicated by the above comments, until confirmed by YOU, NEVER trust factory wiring colors to be standard or still be the same on a used rig...
Previous owners and RV repair services seem to have a perchance to change colors to what they think is standard or to whatever is available at the moment.
Know where a wire goes before connecting..... or, if it is already connected, verify where it is going.

[john warren]

Originally Posted by Perry J

Disconnect the gerrn wire and see what happens.
I think your green is the actual ground wire for your 110v system.
John

i have always left my gerrn wire discombobulated...lol

sometimes typos make fun words,,,i love "gerrn" in fact i think i have said "gerrn " myself while working on 12 volt stuff several times

[Perry J]

Originally Posted by Casita Greg

Casita Battery Wiring:

White (12vdc Return leg) & Green (Bonding wire) to battery NEG. (-)
Black (12vdc Power) wire to battery POS.(+)

Why interconnect the 110c and 12v system?

I have completely rewired several eggs, no casita's, and the green, or gernn, wire has always been the bond wire going from the green bond screw on the 110v outlets to the bonding block in the load center.

John

[Don W.]

Thanks everyone,

I am Glad I called Casita before I re-connected everything. The more education always helps, previous owners and Techs can intentionally/unintentionally mess things up. I have almost worked my way through each system and have it back to mint condition.

Our rig was not in bad shape by any means, just little quirks that were not visible, or parts that were close to/ or worn out. I have 3 more LED lights coming today and all lights will be converted. Then this winter the interior woodwork will be redone!

Don

[Casita Greg]

Quote: Why interconnect the 110c and 12v system?


Perry,
The bonding wire is not the same as a ground wire. Many people mistakenly think that one can be used for the other since they both seem to come to the same terminal end, (i.e. a common chassis ground).

First, the bonding wire (green) is neither exclusively 120vac nor 12vdc in nature. A bonding strap is not, and should not be, used as a normal "current-carrying conductor." It is also NOT a ground wire either. The path for any current flow is circular in the sense that it must be able to complete a "round trip". If electricity cannot find its way home, you have an open circuit. A bonding wire (aka the green one) serves the purpose of "bonding" electrical equipment, both to each other and also to the frame (a point of grounding in case of an electrical malfunction which may cause a hazard from energized equipment contact.) This serves to provide a safety current path should the casing or other exposed metallic components would somehow become energized, and exists to prevent you from getting electrocuted if you touch a "hot" electrical enclosure or chassis should an internal short occur in one of your components. It also serves to help reduce stray electrical interference, such as static, in and between various electrical components in your rig. This wire should always be connected and never left "dangling loose."

The ground wire (white in this case) is strictly the return leg of your 12vdc current path back to the battery. This allows for that "circular current path" needed to hook up any of your 12vdc loads. If your 12vdc circuits can't find their way home back to the battery, you don't have a complete circuit.

I can go into more extraneous details, ad nauseum, about various electrical therory, but really...who cares? Most people don't want an education in electrical theory, just a basic understanding of why things do what they do. Hope this helps.

[Perry J]

I understand all of that
I just upgraded the the 110/220v service into my home with a new 200 amp panel.
I just finished a complete rewire, 110V and 12v of my Lil Bigfoot.
I have rewired several othere trailers NONE of them had the Green wire,110v, interconnected to the 12v system.
I know the green has nothing to do with delivering electricity to the appliance or light.
It is there to send short circuited 110v electricity to ground through the ground lug on the trailer 110v supply cord into the copper stake driven into the (ground) near the exterior power supply.
Why isn't there a green wire in the 12V fixtures?
There is a white wire to complete the circuit and another colored wire, never green, to deliver the 12v to the fixture.
John

[Raz]

Hi John. It's common practice to tie one side the DC source to chassis ground. Use of a green wire is arbitrary. They can do it at the battery or the converter. Back in the good old days when electrical equipment was housed in metal chassis, tying all that metal together was a safety issue. With plastic cases that's not an issue any more.
The best reason I can give you is that it reduces the possibility of parasitic effects. An electrical circuit can behave as designed on the test bench, but installed, can behave quite differently due to long wires, proximity to other electronics, and a multitude of other things. For example, power supplies can turn into radio transmitters. That sort of thing. Good grounding reduces that kind of unwanted behavior. Will your DC appliances work without it. I suspect so. But if all of a sudden you LEDs dim or you get a fuzzy picture on you TV, poor grounding could be the cause. Raz

[Ed Morris]

We bought a 1994 Casita in June and the battery was not only dead, but wired incorrectly. The previous owner assumed black was negative. The power center relay clicked constantly when we attempted to use battery power.

With a new battery and the black to positive and the white to negative, everything worked fine. There' s another wire, usually, but not always, green, that should run from the negative battery terminal out through the bottom of the battery compartment and connect to the trailer frame.

Apparently reverse wired batteries aren't uncommon due to confusion over the different color conventions used in RV wiring.

Hope this helps.