Battery on/off -- Pos or Neg side?

[mbtelguy]

Just a caution and something else to consider
when wiring up a battery disconnect switch.

If the switch is in the battery positive side I suggest you
make sure the power to the breakaway switch
is not disconnected, just in case you forget to
turn on the batteries, prior to towing trailer.

If the switch is in the negative side and the battery
ground is open (switch off position)
there will not be power to the breakaway switch.
Maybe this justifies a positive side disconnect
switch wiring.

Gary

[dnaraG_1M]

Originally Posted by mbtelguy

Just a caution and something else to consider
when wiring up a battery disconnect switch.

If the switch is in the battery positive side I suggest you
make sure the power to the breakaway switch
is not disconnected, just in case you forget to
turn on the batteries, prior to towing trailer.

If the switch is in the negative side and the battery
ground is open (switch off position)
there will not be power to the breakaway switch.
Maybe this justifies a positive side disconnect
switch wiring.

Gary

True......If the power switch is off while you're towing.

If parked, breakaway switch is a moot point - as long as
it is not activated!

Is it common to have the power switch OFF while towing?
Had no plans to do that - want the reefer to have 12v power
and propane available.......

cheers,
johnd

[herk7769]

Originally Posted by dnaraG_1M

Is it common to have the power switch OFF while towing?

Not common at all.

With the switch "off," regardless of which side + or -, you will not have emergency brakes (breakaway switch) OR battery charging from the tow vehicle. You SHOULD have 12 VDC to the camper for the fridge through the tow vehicle's + 12 VDC connection.

[Malco]

Guess people better make sure that's on their checklist so they don't forget to turn it on.

[mbtelguy]

I hope that people are not driving around
with the battery disconnected. However it
is very easy to forget to turn a battery disconnect
switch on.
To avoid this, it is very easy to rewire the breakaway
switch in a way to eliminate this possibility.

In regards to the negative side just think
about how difficult it would be to rewire
the brake circuit to prevent this.

Gary

[dnaraG_1M]

Originally Posted by mbtelguy

I hope that people are not driving around
with the battery disconnected. However it
is very easy to forget to turn a battery disconnect
switch on.
To avoid this, it is very easy to rewire the breakaway
switch in a way to eliminate this possibility.

In regards to the negative side just think
about how difficult it would be to rewire
the brake circuit to prevent this.

Gary

Yep. I see no major downside to wiring the breakaway switch
directly to the battery.And upside if you are as forgetful as I.
Although I'm new to TT, I've pulled flatbeds for decades.
All the flatbeds I've owned have the breakaway switch wired
directly - no cutoff switch. Never had a problem, just put
the plate back into the breakaway switch after testing
the brakes and there's no battery drain........

Rewiring mine to go around a negative cutoff switch would
be a pain - crawling under TT and pulling the hubs - but not
difficult if both magnet wires are available (like all 4 of
mine are).....

Like you imply, that's a good "human factors" reason for
a positive lead cutoff switch......if you wire the breakaway
switch to be always hot so forgetfulness does not equal
disaster.


cheers,
johnd

[Mpjduff]

New to camping in a trailer. Do you need to install a switch? I am not electronically inclined so is it hard. Should I go and disconnect my batteries while it is sitting. I left them hooked up I know they are dead is that bad?

[gljurczyk]

I agree with iggy's comment, You should always install your disconnect at the pos. side. I was surprised to see in our new Rookwood 8289WS, that I had one. nothing fancy just a push in for juice and pull out for the disconnect. I have installed a second battery and wired it to the first on the op. side of the storage area. I had to install a bigger wire being I did not want a voltage drop. I used another vented battery box, but I put a Tee in the vent tube to the original factory installed vent. I do not like drilling holes in a new unit.

[Mountainmanbob]

Originally Posted by Mpjduff

I left them hooked up I know they are dead

is that bad?

it's not a good THING
to leave them drained (dead) low for long
you might possibly start with
adding distilled water to your battery
then put a charger on it

voltmeters come in very handy
they tell us exactly
what the battery has
we can see how long it holds a charge

note
in most cases that I have seen
if
the battery water has gotten below
the plates in the battery
yes
damage has been done

Mountainman

[sail2liv]

Boat has marine on/off/1/2/or both switch on positive side....has worked fine for 34 years....HOWEVER.....need for fused items on negative side can
be prudent....once in 34 year I had current come in from the negative side and fry all electronic and other items......items are fused on the positive side only most of the time.....so they are protected from high volts/amps on that side but are not protected from the negative side.....food for thought in high voltage storm areas especially when pluged into shore power......when making changes might be something else one might do