battery question

I have these Cole-Hersee disconnect switches. These switches have a contact area that is sealed with an O-ring. Pricy, but very good for wet areas. The 75920 is dust proof and immersible.

mjmeyers wrote:

Lynnmor wrote:
I went thru two of those switches in one summer. Junk! They corrode inside, get a Blue Sea switch.

Can you mount this on the battery case in a horizontal position or does it need to be vertical?

Best check with the maker. I mounted on the side of the box so that it won't hold water.

Lynnmor wrote:
I went thru two of those switches in one summer. Junk! They corrode inside, get a Blue Sea switch.

Can you mount this on the battery case in a horizontal position or does it need to be vertical?

I went thru two of those switches in one summer. Junk! They corrode inside, get a Blue Sea switch.

Let me see if I understand you

You get 12.6 (normal resting voltage for a fully charged battery) at the battry

But only 9 inside.

Bad connections, (Most likely battery terminals but all others are suspect)

Bad wire.. YES bad wire,, I have actually had a BAD WIRE, not the connection but the wire itself

Test procedurt.. Method two: Turn on an interior lamp. DO NOT plug in.
Using a volt meter start at the batteries, Negative to positive 12.6 you alreay said

Chassis to positive If lower, bad ground connection

Now move out alone the positive line, EVERY time you come to a connection measure the voltage.. Example if you come to a self resetting circuit breaker (GOOD CHANCE HERE) there are two terminals, Battery wire goes to one, other runs off to "House" (RV). measure at BOTH terminals

When you see a 12.6 on one side and a 9 on the other.. Problem between test points.

Method 1: (Better if you have done it before)

Replace meter with a test lamp, This is a device that looks like an ice pick, clear or translucent handle with lamp inside, wire comes out of handle

Replace 12.6 with BRIGHT LIGHT
Replace 9 with DIM LIGHT.

Since you have it solved maybe this analysis will help you wrap your head around the issue.

A water hose is connected to a faucet that has 50 lbs of pressure. On the end of the long hose is your sprinkler working just fine until someone steps on the hose and the water spray diminishes. The resistance causes the pressure (voltage), to be much lower at the sprinkler. The pressure at the faucet (battery), has not changed.

That switch probably will come apart and can be cleaned and lubed.

CT_WANDERER wrote:
Looking at your photo, it looks like the key to your switch is in the vertical plane? Maybe it got water in it to corrode the contacts. Just a thought. Gary

Yes, I've worried about that in the past. It is a marine key, one would think it should be water tight. It has a teflon-like seal that the key presses against when it is turned to the on position and make the contact. That sealed key slot collects water, but who knows how water tight the seal is.

Looking at your photo, it looks like the key to your switch is in the vertical plane? Maybe it got water in it to corrode the contacts. Just a thought. Gary

Thanks to all for pointing me in the right direction on the battery issue. It was indeed the wiring and thankfully a simple inexpensive solution. I had installed this quick disconnect last year.



Taking the disconnect out of the circuit, I now have full voltage in the TT, lights working, etc. Don't know yet if the disconnect switch itself is bad or if one of the connections, which appeared pretty solid, was bad.

May try to reconnect the switch after I get the TT back from the dealer this weekend and see if the problem reappears. Is this a common problem with these types of disconnect switches?

mjmeyers wrote:
I was assuming that if I am still getting the 9V inside the TT that the wiring must be OK (i.e., there is a connection to the battery). But I'm no electrician. Seems the consensus is that it is the wiring. If there is a faulty ground, would that lead to the voltage drop? I will see what I can figure out with it tomorrow. I appreciate the help and am thankful it is not the batteries!

If the battery voltage is good and stays constant, then the only way to have a lower voltage inside the camper is if current is flowing in a branch circuit somewhere which is causing the voltage drop.

Turn off all of your DCV loads at the fuse panel and measure the voltage supplied to the fuse panel.

If it still measures low, your problem is between the battery and panel.

If it measures OK, turn on one branch at a time while monitoring the supply side connection point.

When you find the branch causing the loading problem, trouble shoot that branch by systematically disconnecting the various loads on that branch while monitoring the supply voltage.

A bad battery would have been easier...

:)