Battery on/off -- Pos or Neg side? - Page 2

Bill_C · 09-19-2011, 10:30 PM

Quote:

Originally Posted by Iggy

Switch the Positive side. The reason why is if you jus switch the negitive you can still make a direct short inside the trailer from a positive line to the frame which is ground.

If you switch the positive at the battery you will never have the posibility of a short inside your trailer.

My 2 cents

If the negative is disconnected at the battery, as per a switch, and it is off, then you cannot ground (short) anything anywhere. It is the same as taking the negative cable right off the battery.

I am a negative kind of guy.

EinDog · 10-29-2011, 07:45 PM

<<If you switch the positive at the battery you will never have the posibility of a short inside your trailer.>>

Doesn't make any difference. Once the battery is disconnected in any manner, at one of the posts, it is out of the circuit.

Here is why you disconnect the negative cable first when you change a battery:

If you put a wrench on the positive cable, and in the process of unscrewing the bolt touch the wrench to the frame, then you have a direct short of the battery to the frame, with a pretty decent conductor. If you loosen the negative side, you can jump it to anything except the positive cable and it will not bother anything. Once you have the negative disconnected, then you can work on the positive and not worry about shorting it to anything (so long as you don't have an inverter trying to make 12V for you.

Once the switch is in place, it doesn't matter which side you open. If I were to put in a switch, I would probably put it on the positive side, but do the work while the negative cable was disconnected. One of the advantages of having the switch on the positive side is that it gives you a stud connection to connect a battery charger or other accessories. But you need to make sure to protect these connections from accidental shorts.

amxpress · 10-29-2011, 08:28 PM

Quote:

Why do builders place a fuse on the positive wire closest to the power source?

The answer will tell you why you need to switch the Positive wire and not the Negitive.
__________________

Trouble is, we're dealing with a 12V DC system, NOT a 110V AC system.
Answer me this; why are switches in automotive electircal systems placed on the ground side of the circuit?
Though in reality, it doesn't make a difference which side you connect the switch, I have always placed it on the ground side in automotive applications.

07ultra · 10-30-2011, 06:08 AM

ok , silly question but why not save the time and money and just disconnect the battery

**KyDan** · 10-30-2011, 06:20 AM

Quote:

Originally Posted by 07ultra

ok , silly question but why not save the time and money and just disconnect the battery

If you go camping a couple times a year this is a fine plan.
We go 6- 10 times a year. I want my battery connections to be tight
and I coat them with a compound that keeps corrosion to a minimum so
they are very messy. AND it's a pain in the neck to have to loosen
the tie down strap and take the battery box top off each time.

A switch is just SO much easier.
My 2¢

And welcome to the group!!

youroo · 10-30-2011, 06:56 AM

Quote:

Originally Posted by BackInAction

When I add an on/off to my battery box, which side (positive or negative) should I install the switch?

It seems like a silly question to me, but I've seen significant debate in another forum without any real conclusion.

Now you have seen significant debate on this forum! What is the conclusion?? Youroo!!

07ultra · 10-30-2011, 09:45 AM

did not really see a time he was disconnecting the battery , thought it was more of just a winter storage thing , so next question is why put in a disconnect at all , had one on my last camper and it went bad , had alittle power going through but not very much , lights very dim , thought it was a bad battery and had it checked , found out it was good , checked things more and found out disconnect went bad so just bypassed it , leave my batterys in year round , pluged in or on a tender

EinDog · 10-30-2011, 07:07 PM

<<Answer me this; why are switches in automotive electircal systems placed on the ground side of the circuit?>>

When you get into electronically controlled devices things are a bit different. It is easier to pull a wire to ground with an electronic driver. But when you are working with mechanical switches, those were typically switching on the positive side. A few of the circuits (like a dome lamp) would have the ground connected through a door switch (or multiple door switches) that were a direct connection to the frame. Or idiot light type sensors- The lamp would have 12V to it and the switch would connect the other side to ground when the light should be on.

Either side works.

BackInAction · 10-31-2011, 07:02 AM

Quote:

Originally Posted by youroo

Now you have seen significant debate on this forum! What is the conclusion?? Youroo!!

I installed it on the positive side. That said, I've enjoyed the discussion.

Len & Cheri · 10-31-2011, 07:21 AM

Quote:

Originally Posted by BackInAction

I see this one used often as well, mounted right on the top, or side, of the battery box...

Amazon.com: Pico 5575pt Master Batt Isolator Switch: Automotive

That's the switch I had on my other TT and it lasted just over a year. Seems the inside wore out. Sometimes i would turn it on and it wouldn't make good contact inside. I would have to jiggle the key to make it connect. This is what I did on my new TT and the switch seems to be very well built. I took a thin piece of metal and modified it to where I could fasten it under the tongue jack, then I secured the switch to that.

**KyDan** · 10-31-2011, 07:30 AM

Quote:

Originally Posted by 07ultra

, leave my batterys in year round , pluged in or on a tender

There are good switches and junk ones just like most everything else in this
world.
Your plan works for you but we are mostly talking about folks who don't
or can't leave their trailers plugged in or on some sort of charge all the time.
Those folks need to disconnect their batteries or pull the appropriate fuses
or their batteries will be drained totally dead in a few weeks.

BackInAction · 10-31-2011, 07:56 AM

Quote:

Originally Posted by KyDan

Your plan works for you but we are mostly talking about folks who don't or can't leave their trailers plugged in or on some sort of charge all the time.

This brings up another question (maybe I should start another thread)?

I will take my batteries out of the camper after our last trip (end of Nov) and bring them home (Ohio). Can I just place them on the floor of the unheated garage and throw a charger on them once in a while for an hour or so? Or should I take them to the basement and do the same?

FWIW, I just have a pair of cheap-o Group 27s. And an inexpensive charger.

**KyDan** · 10-31-2011, 08:03 AM

As long as you keep them reasonably charged cold weather won't hurt them.
I'd not carry them down the basement stairs if I was you but that's just
my 2¢.

Also don't let people tell you they must be set on wood and not on the
floor. Modern plastic case batteries don't know the difference.

Triguy · 10-31-2011, 08:21 AM

I agree with Kydan.

As for charging by time, such as putting it on for an hour or two, you are better off if you make sure to charge fully each time you put them on the charger. You will want to avoid undercharging.

So, keep them on the floor in the unheated garage, check the volts periodically and recharge fully when needed. Or, get a battery minder or battery tender that will do it automatically for you.

BackInAction · 10-31-2011, 08:30 AM

Quote:

Originally Posted by Triguy

Or, get a battery minder or battery tender that will do it automatically for you.

Any recommendations? There seems to be a billion battery chargers on the market.

**KyDan** · 10-31-2011, 08:32 AM

I don't work for these guys nor do I have any monetary connection but
they have the lowest price on the web for this little automatic charger.
It's fully automatic and comes with 2 wire harnesses.
One you can connect into a trailer and charge without removing batteries.
And the other is a set of alligator battery clips so you can clip it directly
to the battery posts.

It's just $20 including shipping.

http://www.derbycycles.net/productde...urce=searchbar

Triguy · 10-31-2011, 09:43 AM

I use the battery tender Jr for my motorcycle battery. It has worked well for me for many years. Surprisingly well considering that its 12 years old now.

I should add that I use a Stanley 40amp Smart charger for the trailer for regular charging needs. I haven't used it as a trickle charger over the winter, although I don't see why that wouldn't work.

racedaymechanic · 01-23-2012, 10:16 AM

Quote:

Originally Posted by Iggy

Switch the Positive side. The reason why is if you jus switch the negitive you can still make a direct short inside the trailer from a positive line to the frame which is ground.

If you switch the positive at the battery you will never have the posibility of a short inside your trailer.

My 2 cents

If you put the switch on the negative side, there is no ground if its off

**Herk7769** · 01-23-2012, 02:02 PM

Quote:

Originally Posted by racedaymechanic

If you put the switch on the negative side, there is no ground if its off

This is 100% true.

With a DC battery system there is no difference if you disconnect (switch off) the ground or positive leg. There is no power to the camper at all since there is no return path to the battery.

Walke · 01-23-2012, 05:04 PM

Always switch the positive side,(unless you are in Europe) the direction of the current doesn't matter to a contact switch. I don't believe a sound technical reason can be made for switching the negative (ground) side of a battery.

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