Author Topic: Adding 12 volt cut off switches to a 1998 Patriot Savannah  (Read 694 times)

Carl Boger

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Adding 12 volt cut off switches to a 1998 Patriot Savannah
« on: January 12, 2021, 08:52:57 PM »
I was thinking about adding 12 volt battery cutoff switches to my 1998 Patriot Savannah.  It currently has 2- 12 volt Chassis Batteries and 4- 6 volt lead acid GC batteries.  Most or all Coaches I have seen only have 2 battery disconnect switches. 

When I looked at the wiring diagram for the 1996 Patriot on page 21 it shows one Positive lead going from the House batteries to the Isolator, and one Positive lead going from the Chassis batteries going to the Isolator.   It also shows a 2nd Positive wire on the Chassis side that goes directly to the Starter.  I think this is the same wiring diagram I need for my 1998 as all the batteries appear to be wired up the same.

So I am thinking that the 2 -12 battery Cutoff switches/disconnects go to the wires that attach to the Isolator.  Is this Correct?  I can not think of a good reason one would need to have a cut off switch going to the starter, if anything it would just be a spot that would loose some starting voltage.

I am doing this to clean up my battery wiring some, or really just to do something positive while I am still on shut down from the CHINA VIRUS!

I don't know why these MH's came with out cutoffs, but I guess they really are not needed since it has made it this far with out them.
Thanks for any help.
Carl

98 Beaver Patriot Savannah

Carl Boger

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #1 on: January 15, 2021, 01:11:07 AM »
Ok with no responses does anyone see any problems with adding the cut off switches before the isolator?

I now have everything I need to clean up the wiring and I am ready to move forward after I get home on Wed.  I am confident I can move ahead and not damage anything, but I have seen many diagrams that show the switches after the Isolator, and some that had the switches with the alternator on the battery connected side.

Any one see any problems with the switches since I am not wired like the others? 

Thanks
Carl

98 Beaver Patriot Savannah

Bill Lampkin

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #2 on: January 15, 2021, 01:29:25 AM »
Carl, I'm not familiar with your coach, but you might want to take a look at the wiring diagram for 2004 Patriot here on Coach Assist. The diagram clearly shows where the disconnect switch is in relation to the 'Big Boy' isolator. Might shed some light on your issue.
2005 Patriot Thunder Lexington, 3 slides
40' tag axle (short wheelbase)
525 hp C13

"Liberty is not the power to do what one wants, but it is the desire to do what one can" J-P Sartre; inscription in base of Statue of Liberty

Carl Boger

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #3 on: January 15, 2021, 02:01:33 PM »
Thanks Bill,

I did look at that, but my coach is wired like the 1996 Patriot wiring diagram.  I am confident that putting the cutoffs before the isolator won't harm anything since it is just like removing the battery cables.  The one line that goes to the starter is only activated or charges when the solenoid is activated by the keyed switch.  Just trying to check things out first.  With wiring there are many ways to accomplish the same thing.  Some are better/smarter than others.  Thanks everyone
Carl

98 Beaver Patriot Savannah
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Eric Maclean

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #4 on: January 15, 2021, 05:43:41 PM »
Carl
The starter in itself is not likely a parasitic draw point but you have to check at the back of the starter and find what else they have connected to that cable the best way to guarantee battery disconnect is to put the disconnect between the battery bank and all loads starter cable included of course this means the disconnect has to be capable of at least a 400 amp current and you are correct this does introduce an other possible volt drop area  it seams all of life is a trade off.
How ever If you were ambitious you could I suppose test anything connected to the back of the starter for possible parasitic draws and if there are none there would be no reason to have the disconnect on the battery cable or for that matter if one of the feeds off the back of the starter turned out to have parasitic draw you could extend that wired and connect it to the battery disconnect instead of the back of the starter.
To my knowledge the only real parasitic load for the engine side would be the Cat ECM and possibly Transmission TCM and they usually connected them directly to the battery bank with there own 10 amp inline fuse to ensure a good clean battery feed voltage while cranking.

As you sugested there are several ways to install the disconnects , usually there installed on the positive cables between the battery bank and the loads .
On the chassis side remember that there are several loads connected to the battery bank battery cable to the starter, generator power cable and there are usually two smaller power feeds one for the engine ECM and the other for the transmission TCM these both can have a parasitic draw when the vehicle is not running and over time they will deplete the batteries therefore they need to be disconnected with the battery switch .
when you're done there should be only one positive battery cable connected to the battery bank to the disconnect  and all of the loads should be running off the other side of the battery switch.
Remember the cable running from the battery bank positive to the disconnect and the disconnect itself must now carry the load for all the loads connected to the disconnect and should be sized accordingly although you don't start the gen set and the engine cat the same time .
The same applies to the coach house battery bank when done right there should be only one positive cable running from the battery positive to the disconnect with the possible exception of any solar charge system which you may want to keep the batteries toped up during storage.
You may choose to install  isolated terminal lugs to the frame beside the grounding lug and run the cables from each battery bank to and then run from there to there prospective disconnect so that the stress put on the cables when pulling out or pushing in the battery tray is not placed on the battery disconnect terminals.
Hope this helps
Eric


« Last Edit: January 15, 2021, 06:24:22 PM by Eric Maclean »
1997 Patriot Yorktown
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2009 Chevy HHR
Roadmaster falcon tow bar
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Larry Fritz

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #5 on: January 15, 2021, 09:49:25 PM »
To Carl: I have my 98 Patriot Ticonderoga (37') wired exactly like Eric described in his great post to you. I installed mine many years ago and have the switches about one foot from the battery banks. I used one switch on the two chassis batteries and a second switch on the four coach batteries. Zero issues or problems. I just open the cargo door and flip the switches. Very easy to install. I would like to influence you. Back then, I purchased a small Sperry clamp-on meter (one that will read DC AMPS) that I bought at Menards for about $65 at that time. Now, I cannot fathom how any do-it-yourself person to not have one of these in their tool box. I use it for all kinds of things.  Example here: If Carl wanted to know exactly how many amps or milliamps any wire was pulling then this is a piece of cake.  Example: My Chassis battery set draws about 150 ma normal with everything but the added switch left alone and about 400 ma on the coach battery bank. If I park it for more than two weeks, I shut the switches off; otherwise, I let them on.  If you do buy one of the clamp on  units be sure to get a small one. The classic larger ones like the HVAC techs use are to large. And, be sure to get a digital one. It is simple to use.  Hope this could help sometime.

Larry Fritz
Larry Fritz

Bill Lampkin

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #6 on: January 15, 2021, 10:31:44 PM »
Here's a small clamp on AC/DC multimeter. Very well made, I've had mine for a couple of years. Comes with a K type thermocouple-I used it last summer to keep my Smoky Joe at 220f for cooking ribs!


https://www.amazon.com/UT210D-Digital-Current-Resistance-Capacitance/dp/B0753FY711/ref=sr_1_5?c=ts&dchild=1&keywords=Clamp+Meters&qid=1610749690&refinements=p_89%3AUNI-T&s=industrial&sr=1-5&ts_id=5011680011
2005 Patriot Thunder Lexington, 3 slides
40' tag axle (short wheelbase)
525 hp C13

"Liberty is not the power to do what one wants, but it is the desire to do what one can" J-P Sartre; inscription in base of Statue of Liberty

Bill Lampkin

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #7 on: January 15, 2021, 11:21:28 PM »
On our '05 PT, the inverter is fed directly from the battery, bypassing the coach battery disconnect switch. My guess is that they didn't want a high amp load like the inverter running through the switch, as the switch could heat up and fail (read catch fire).  One side effect from this is that whenever I pull off the negative cable from the coach batteries, I get a big spark when I reconnect the cable.
2005 Patriot Thunder Lexington, 3 slides
40' tag axle (short wheelbase)
525 hp C13

"Liberty is not the power to do what one wants, but it is the desire to do what one can" J-P Sartre; inscription in base of Statue of Liberty

Carl Boger

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Re: Adding 12 volt cut off switches to a 1998 Patriot Savannah
« Reply #8 on: January 16, 2021, 12:04:39 AM »
Thanks everyone. Eric I will do it the way you described, which is what I had in mind anyway.  I have ordered everything and will get this done when I get back in town.   I really appreciate the insights from everyone
Carl

98 Beaver Patriot Savannah