How Is There Current Flow

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

arcticfox2005

Well-known member
Joined
Apr 18, 2011
Posts
698
In our Winnebago class C the house batteries are under the entry step. I got rid of the two group 24's and bought two 6v golf cart batteries, which are sitting on the floor in the garage. Yesterday I was looking at the battery cables in the battery box and when I moved the positive cable it touched the side of the steel box. There was a spark. Obviously, I think, the source of the current has to be the engine battery but how? Where do these circuits share a common point? Do I have a problem?
 

Isaac-1

Well-known member
Joined
Dec 3, 2016
Posts
5,456
Location
SW Louisiana
It depends on the type of battery isolator you have, some can back flow current in situations like yours, alternatively if you are plugged into shore power it would be from the inverter, the other option is if you have solar panels.
 

Henry J Fate

Well-known member
Joined
Jun 14, 2018
Posts
1,700
Depending on your model and design, early Winnebago's had a switch that would combine the house batteries with the chassis battery full time and labeled AUX or something similar usually on the dash somewhere in a 2 position design. Later years they changed that switch to a momentary switch which removed the ability to connect the house and chassis full time and was designed to be used as a momentary jump start for the chassis engine or a jump start for the generator which ever was needed or available.
 

John From Detroit

Well-known member
Joined
Apr 12, 2005
Posts
25,608
Location
Davison Michigan
There are devices in the RV that store a small amount of power.. Often the converter.. The one I had was what is called a "Filtered" supply.. The "Filter" contains a Capacitor (also called condenser) this is two metal plates with a insulation between them in case you wonder how it's made..
Some of those can hold an amp-second or more. Major spark.

Spot welders.... Actually do much the same thing.. Charge up a capacitor than POP it to spot.
 

A Traveler

Well-known member
Joined
Aug 25, 2014
Posts
387
I think you are all over-complicating this. The OP said, …when I moved the positive cable it touched the side of the steel box. There was a spark…”

Of course there was a spark! If the POSITIVE cable touches the “…steel box…” it has touched GROUND, which is where the negative cable from the battery is connected! It has nothing to do with a back feed, the converter, the battery isolator, or anything else. This is nothing more than a simple short from the positive battery cable to ground.
 

NY_Dutch

Well-known member
Joined
Nov 22, 2010
Posts
7,295
Location
Where our wheels take us!
I think you are all over-complicating this. The OP said, …when I moved the positive cable it touched the side of the steel box. There was a spark…”

Of course there was a spark! If the POSITIVE cable touches the “…steel box…” it has touched GROUND, which is where the negative cable from the battery is connected! It has nothing to do with a back feed, the converter, the battery isolator, or anything else. This is nothing more than a simple short from the positive battery cable to ground.
The batteries are not installed.
 

A Traveler

Well-known member
Joined
Aug 25, 2014
Posts
387
Oh…I didn’t read the OP that way.

As Rosanne Rosannadanna used to say, “Never mind.”

Now you know how old I am. 😉
 

Lou Schneider

Site Team
Joined
Mar 14, 2005
Posts
11,433
As was said above, if the RV was plugged into power the converter will provide power to the positive battery cable. If the RV is unplugged, you may get one spark if it's capacitors are charged. You may also get a spark when you connect the battery as the capacitors charge up. If you get a second spark, check the solenoid that lets the house batteries boost a low starting battery.
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
75,288
Location
At my Silver Springs FL home
There are several ways for that to happen, the most likely being what Lou described (converter on & producing 12v). Or the engine running and feeding 12v to the house side (charging). Another is an LP gas alarm with dual power source. But it's not unusual for an older RV to have been modified at some point in a way that allows power to cross over between house & chassis.
 
Top Bottom