Neg. Cable Off, Stereo Still On!?!?

[Mothership]

In my attempt to isolate my new start battery, I bought and installed a slick disconnect switch (the kind with the turn knob) on the negative post of the start battery. After putting the Adventurer to bed for a few months, I left the dash stereo on using the ignition key and unscrewed the switch fully knowing the stereo would stop operating. My 2 coach battery's were off by way of the Aux. switch on the dash.

To my disbelief, the stereo stayed on!...and my Kwikee step continued to operate as well!...which I thought was also powered by the start battery. I then completely disconnected the negative cable on the start battery and the stereo continued to function,....huh!?... which means there is going to be a parasitic draw on my new battery. 

How do I get the dash stereo and other parasitic draws to shut down and not kill the start battery?
Is there a secret ground somewhere?
Will disconnecting the positive cable on the start battery and reinstalling for the next trip cause damage to any electronics (stereo, chassis computer, steps?)
Will my Trik-L-Start will draw down my coach battery's to keep the start battery charged.

 

[BoomerD]

You MAY have a switch that allows the radio to be powered from the chassis batteries. (Main and Aux) My 2004 Sightseer does. As for the steps...yes, those SHOULD be powered by the chassis battery.(but if you have the house battery system engaged, they might pull power from there)

 

[John Canfield]

...Will my Trik-L-Start will draw down my coach battery's to keep the start battery charged.

No it won't.  It needs to see a charge voltage on the house battery before it will trickle charge the chassis battery.  If your coach is out in the sun, the solar panel might be producing enough current to operate the radio/steps.  There is no easy way to shut it off

 

[SeilerBird]

You should never put a switch on the negative lead of anything. Only switch the positive lead. You are finding out one of the reasons why.

 

[driftless shifter]

My guess.
Your stereo and steps are taking 12v+ from the chassis battery and grounding through the 12v- on the house battery, The house battery disconnect probably only disconnects the house battery positive side.

Bill

 

[Mothership]

BoomerD; Yep, I have the same switch on the dash, and yes you are correct, my rig does power the steps with the start battery. Thank you for the response!

John; Thanks for the info. on the Trik-L-Start, I'm learning a lot from this forum!

Seiler; The switch I bought will not fit on the positive post. Everything I have learned, even in emergency response (retired Firefighter) is that you never cut or use the positive to disconnect a battery. I'll give pulling the positive cable and see what happens. Even in jumping a battery, I understand that you hook up the negative last. Maybe things and technology has changed.
I appreciate your response, thank you!

driftless; I think you are on to something!

My next step is to disconnect the negative posts on the coach battery's and see if that will kill everything.
Thank you everybody for your input, ideas and offering you knowledge. Happy traveling!

Mike

 

[Lou Schneider]

The reason you don't disconnect the positive post first is so your wrench doesn't arc weld itself in place if it bridges between the positive post and a grounded surface that's still connected to the battery's negative post. 

This isn't a concern with a disconnect switch so it's fine to put it on the positive side.

Just about every power switch in the RV is likewise on the positive side.

 

[HappyWanderer]

A circuit will find a path to ground in ways and places that you would never think of. I had a broken ground strap in the engine compartment of my car many years ago, and the wipers would come on with the defroster. That was fun to track down.

There is an ongoing debate within the amateur radio community whether radios should be grounded directly to the battery or if the negative lead should be fused, due to the possibility of high currents finding a path to ground via the antenna cable or through the radio itself.

 

[Old Racer]

Even worse than arc welding the wrench to ground is connecting the wrench to ground through your wedding ring, which will likely melt with your finger still in it. Ouch plus!

 

[Mothership]

Lou; Thanks. I was thinking just about the battery, not thinking bigger like the whole vehicle.

Happy; Interesting! troubleshooting electrical problems has never been my strong point.

Old; I had a friend that welded his metal watch band to his wrist by crossing the positive terminal on a alternator and a ground!

Thanks everybody,
Mike

 

[Charlie 5320]

My 95 Challenger steps were powered from the coach batteries, but had a power wire to the ignition switch. Also your radio may be powered from both sources, and may have a dash switch so the radio can be used with the ignition in the off position.