Install Battery Disconnect Switch

[Castiniron]

Ok reading through these posts - it looks like several options are available. The simplest for me with the two inline batteries on my '17 FC 25' FB is to take both negative leads (as they are longer), 1 from the inverter and 1 from the converter and attach to 1 post on the cut-off switch, using the other cut-off switch post, attach and run a new black wire back to the negative battery post that was originally used by both converter and inverter black cables. Understanding that I'll need to modify the converter cable with the clamp/cover to a ring in order to connect to the cut off switch. Does anyone see any issues with this? Thanks for your help!

[Ronyx]

Hi,

I have been planning on installing a cut off and initially was going to put the cut off switch on the negative cables. It has just occurred to me thought that since I run two 6 volts in series that perhaps it would be alright to simply put the cut off on the cable that connects the batteries in series? Is this an acceptable solution from an electrical and safety perspective?

[Zil]

Disconnecting the inter-cable on two six volt batteries will work. The one safety is the one battery still connected to the chassis has a positive end that can short to the chassis when some unforeseen happens. The disconnect switch has a hot side when off.

[SYC2Vette]

Just to chime in, we put our disconnect on the ground side, as most folks with disconnects on their classic cars do. I believe that most racing organizations require a disconnect on the positive or non-ground side FWIW.

Regarding smart chargers, we use a Inteli-Power PD 4 stage, one big advantage of that charger is it will prevent sulfation by monitoring non-use and applying appropriate charging conditions. Sulfation as you probably know is the main cause of RV battery failure.

[gypsydad]

Originally Posted by MIFC

Hi Gypsy; is this blade switch installed in your 2017 or 2014 trailer? I’m assuming you don’t have the 2014 any longer, but just checking. I tried to install a blade in my 2014 this morning and it was too tall, door would not shut.

Thanks!

Just saw this question...sorry, but yes, the one in the picture is of the older 2012 which we do not have anymore. I do have the blade on my 2017 model, with 6V Trojans, but it is a horizontal switch this time. And, yes, mine is also on the ground to positive connection between the two batteries. Works fine.

[tjwoods1]

I too am considering a battery disconnect like this: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I have two 6v batteries wired in series. Where would I connect the battery cut off switch to these batteries? Do I only need to install it on the one of the negative posts?

[Zil]

It is always better to disconnect the negative end of the battery set. Disconnect the negative from the chassis end.

[ROBERT CROSS]

Ours...🤓

Black...U/S
Blue...Isolation

Bob
🇺🇸

[gypsydad]

Originally Posted by tjwoods1

I too am considering a battery disconnect like this: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

I have two 6v batteries wired in series. Where would I connect the battery cut off switch to these batteries? Do I only need to install it on the one of the negative posts?

Here is a picture of the side throw knife switch on my 6V Trojans in my current 28', and the connection I had on my older 25' 12V's with top throw knife switch. I run between negative terminals on the 12V and between negative to positive lead on the 6V's.

[tjwoods1]

I have two 6v batteries wired in series and am thinking of putting in a battery disconnect switch. I noticed that some say “Amp Rating: 100A Continuous Rating (125A intermittent / up to 1 minute)” and others “300 Continuous Rating (500A intermittent/5 min) minutes)” My 6v batteries Amp rating is 225. Do I need to pay attention to the amp rating of the battery disconnect switches to accommodate my batteries?

[rmkrum]

The amp rating of the batteries is 225 amp-hours, a measure of battery energy capacity. The amp rating of the switches is just the number of amps you can draw through the switch. If you have really big battery cables and an inverter (supplies 120 volt AC outlets from battery power) go with the heavy 300 amp switch. If however you have smallish battery cables (8 gauge or less) and don’t plan to have an inverter in the future, go with the 100 amp switch.

As a data point, I have installed a 250 amp switch because eventually I plan an inverter and have replaced my OEM battery cables with bigger ones. My main battery fuse is currently rated at 80 amps because I don’t have a need for more than that load at present.

[wampler]

So I'm assuming that I can leave all the wires as they are and put a shut off switch on the negative or positive post of each battery?
( really confused and afraid to run all cables to positive and all cables to negative )

[wampler]

You have totally lost me..... I have no electrical knowledge.

[fran&frank]

You just need one switch. go back and look at the diagram on post number three in this thread.--Frank

[gypsydad]

Originally Posted by fran&frank

You just need one switch. go back and look at the diagram on post number three in this thread.--Frank

As Frank notes, only need one disconnect switch; see my pictures in post #29 above. The Interstate 12V batteries are shown with the switch between positive and negative connection in the first picture (green). The second picture on the right, shows the switch between positive and negative leads on the 6V Trojan batteries I am currently running on my 28' AS FC. I chose the mechanical switch, but there are other choices out there that work also.

[ROBERT CROSS]

Originally Posted by fran&frank

You just need one switch. go back and look at the diagram on post number three in this thread.--Frank

But most of us will end up with two.
#1 the factory use/store
#2 the one YOU install.

Bob
🇺🇸

[Mollysdad]

Originally Posted by dasams

The electrical diagram shows that a 4 ga wire connects one of the batteries to the inverter and that a 6 ga wire connects the other battery to everything else, including the jack.

Not exactly.
The 4 ga wire runs to the inverter, while the 6 ga. wire runs to the converter. The jack has it's own 12ga. lead directly to one of the +terminals. (Yellow ring terminal) Since the positive leads use both batteries, there's no one place to install a simple on/off switch.
Conventional wisdom says to put the loads across both batteries, so the +from the converter will be on battery 1 while the - will be on battery 2. Reverse the process for the inverter. (+on bat 2 positive, - on bat 1 neg.)

I choose to put my switch in the negative path, simply because those leads are longer and would reach my switch without a splice. I used a marine double pole/single throw switch where "1" is the converter and "2" is the inverter.
So if I move the switch to "1" I send power to the converter but not the inverter. "Both" powers both, and "Off" disconnects everything.

Once you grasp the concept of how to send power, the wiring is easy.

Here's my installation:
https://www.airforums.com/forums/blo...sconnect-3036/

[wampler]

why disconnect the batteries when connected to shore power?

[gypsydad]

Originally Posted by wampler

why disconnect the batteries when connected to shore power?

We disconnect ours when storing for long periods (weeks), as a precaution. Most all AS's before 2018 models, had a single stage converter, which could (and did) overcharge or "boil the water out" of the cells, causing them to go bad. Many of us replaced the original with newer 4 stage converters which will "tend" the batteries once charged. They say no harm in leaving plugged in with these newer 4 stage converters; but out of precaution for long periods, we disconnect anyway while in storage, and plug in a few days before use.

[Mollysdad]

Originally Posted by wampler

why disconnect the batteries when connected to shore power?

If I'm using the trailer, I don't.
But if stored with power, and older than 2018, the converter is a single stage, so it will continue to charge after the batteries are fully charged. Damaging to batteries over time.

I use the disconnect when I'm leaving it sit for a while and not connected to power.