Tom!

Firstly, I applaud your approach toward tuition of your students, and hope
that they have realized a practical approach to life!

Regarding vehicle batteries.
I can only speak for vehicles here in the UK which usually have several
earthing / grounding points which means that when the connection direct to
the battery is removed, there is a leak to ground should the positive touch
any of the vehicles unpainted bodywork.
Conversely for the re-connection.

As ever, there is a however in that positive earthing used, sometimes, to be
used!

Putting it more simply, if the source of energy is removed, no problem can
ensue.  However, should the source remain connected, it can be an issue!

It is also important to ensure that plus and negative are not inadvertently
connected!  High current for a short time, with low voltage equals welding!

73

David W Wood 
-----Original Message-----
From: For blind ham radio operators [mailto:[log in to unmask]]
On Behalf Of Tom Behler
Sent: Friday, October 24, 2014 9:37 PM
To: [log in to unmask]
Subject: Best procedure for connecting and disconnecting a 12-volt battery

Hi, all.

 

I am sure that, to some, this question might seem to be very elementary,
especially for someone like me who holds an Extra class license.  So, please
bare with me, and understand why I am asking the question.  As a college
professor, I always try to teach my students not to simply memorize
procedures or concepts just for the sake of doing so.  I tell them that real
learning involves understanding the procedures and/or concepts and the
reasons behind them.  I also stress that true learning involves being able
to apply what you have learned to real life situations.

 

Anyway, here's my question:

 

Earlier this afternoon, my XYL and I were in the process of getting our
summer camping trailer winterized for the season, and taken to a local
facility for winter storage.  As we worked, it came time to disconnect the
house battery from the unit, so that it can be put on a trickle charger
during the winter months.

 

Before we disconnected the battery, we were discussing the best and/or
safest procedure for doing so.  We never worried about this with the
drivable RV we used to have, because it was always kept in our driveway and
plugged into our main house power all winter.

 

Anyway, my proposed approach was this:

 

When disconnecting the battery, disconnect the positive side first, and then
the negative.  The idea here is that you always have the negative or ground
connected when you're working with the battery.

 

When re-connecting the battery, I proposed connecting the ground terminal
first, once again, to give you a ground to start from, and then connect the
positive terminal last.

 

My XYL's approach was the opposite:

 

She argued that when disconnecting the battery, disconnect the negative
terminal first, and then the positive.  . When connecting, connect the
positive first, and then the negative.

 

As a smart person who has much faith in my XYL's judgment, I decided to go
along with her proposed approach, and happily, we are both still here to
talk about it.

 

However, I know that I have connected and disconnected many a battery using
my initial approach, and I've survived that as well.  Perhaps I just got
lucky, but I always thought I was proceeding with care, and with the correct
procedure.

 

Once again, I hope nobody minds this question, but I consider everyone here
to be knowledgeable on many things, and I trust that you will all be able to
go with the idea that the only stupid question is a question that goes
un-asked.

 

Your wisdom on the topic would be most appreciated.

 

Thanks for listening.

 

Tom Behler: KB8TYJ