Go Back   Montana Owners Club - Keystone Montana 5th Wheel Forum > MOC on M.A.R.S. > Montana Problems, Problem Solving & Technical Help
Click Here to Login

Reply
 
Thread Tools Display Modes
 
Old 07-10-2020, 01:10 PM   #1
Turtle-Ham
New Member
 
Join Date: Jun 2017
Location: Box Elder
Posts: 7
M.O.C. #19992
Battery Cutoff Switch Resistor?

Greetings all. There have been lots of questions about Battery Master Cutoff Switches, but here's one I've never thought to ask until now that I'm faced with an issue.

Our batteries failed to charge, and I verified that the Progressive Dynamics converter is putting out the 13-plus volts that it should. (All fuses on the converter and elsewhere tested good.) I checked the Keyed Battery Cutoff Switch (with removable key, but no reset switch) inside the convenience center. I wasn't happy to find that the nuts had been screwed on only finger tight, but tightening them did not correct the problem.

I disconnected both wires to the switch and put the ohmmeter across the contacts. The reading was infinite in both the ON and OFF positions even after switching it back and forth multiple times. But after reconnecting it, I measured 1.3 volts across the terminals (vice measuring to ground), so something is inside the switch component that's dropping the voltage albeit a small amount.

(For the record, the batteries are brand new - OK, a month old - and were fully charged when we put them in; they're draining slowly. The rig is a Montana 3721RL fiver. Connections on the converter and the batteries are tight.)

If the switch is of a "simple" on-off toggle flavor (like a light switch), then it would show zero (or close to it) in one position and infinite in the other. But somewhere I saw a sales ad on line (don't remember the site or manufacturer) for a similar keyed cutoff switch that had a 3-ohm 11-watt resistor across the terminals. I'm figuring that that resistor was supposed to act as a thermal overload like some electronic circuits may use. If that's right, then I'd think that measuring across the two terminals of a good switch would have shown a reading of 3 ohms (or close to it).

We've got a replacement switch on order; it should arrive in a few days. We're not leaving for a while, so it's not an urgent thing, but I'm curious if anyone can confirm that some cutoff switches have a low-value resistor like the one I saw on line.

We're full timers who are volunteer campground hosts for months at a time and therefore don't put our rig into storage. Is this particular Battery Cutoff Switch even needed in our case?

TYA! - Jim & Cori
Turtle-Ham is offline   Reply With Quote
Old 07-10-2020, 01:23 PM   #2
Carl n Susan
Site Team
 
Carl n Susan's Avatar
 
Join Date: Oct 2005
Location: Carmichael - CA
Posts: 4,484
M.O.C. #4831
AFAIK there is NO low-value resistor in the switch. It is a simple on/off switch.

There is no need to ever turn the switch OFF (where you can remove the key) if you are full timing.

Did you measure the voltage after the switch? It should also be 13.4 +/- with the converter running.

The other place to check is the red covered self resetting breaker behind the battery. The left one controls the flow of 12V to/from the battery. They have been known to fail.

The 12V charge circuit is pretty simple. From the converter to the disconnect switch in the convenience center, to the self-resetting circuit breaker to the battery.

All of this assumes you are not getting 13.4 +/- volts at the battery when the converter is running.
__________________
Carl (n Susan) Youngren
There is more to life than fuel mileage.
2012 Montana 3700RL Big Sky Package towed by a 2015 Ford F350 6.7L PSD 4WD CC LWB

Carl n Susan is offline   Reply With Quote
Old 07-10-2020, 03:00 PM   #3
sourdough
Seasoned Camper
 
Join Date: Mar 2020
Location: Lamesa
Posts: 85
M.O.C. #26010
I don't know where you are reading voltages but I do know that if you don't see the change in value on the ohmmeter when switching the cutoff switch it is bad. BTDT If you aren't sure, just take the VOM set to ohms, about 200 or 1000 scale, and touch the ends. Whatever that reads should be very close to what you read when you close that switch.
__________________
Danny and Susan wife of 52 years
2019 Ram Laramie 3500 6.4 4x4 CC 4.10 SRW
2020 Montana High Country 331RL
sourdough is offline   Reply With Quote
Old 07-10-2020, 07:22 PM   #4
Turtle-Ham
New Member
 
Join Date: Jun 2017
Location: Box Elder
Posts: 7
M.O.C. #19992
Thanks for the reply; you said pretty much what I expected. I'm still measuring 13.7V at the switch on the converter side; the battery side of the switch is down to 12.2, so it's slowly discharging.

I've flipped the switch back and forth several times, and there's no difference in voltage measurement, so it's pretty apparent that the switch has seen better times.

Other than the fuses, there's no breaker that I've found from the converter to the battery, self-resetting or otherwise. The fuses inside the converter all checked good, so that narrows it down to the switch itself, and a replacement is due in early next week.

I wish I could find the link that I'd found earlier to the cutoff switch with the 3-ohm resistor, if only for giggles!
Turtle-Ham is offline   Reply With Quote
Old 07-10-2020, 07:41 PM   #5
beeje
Montana Master
 
beeje's Avatar
 
Join Date: Oct 2015
Location: westminster md
Posts: 1,576
M.O.C. #17894
Like Carl said, I have owned 3 Rv,s with that switch and have NEVER moved any of them. Short of a bad connection, I don't see the switch being your issue.
__________________
2018 Chevy 3500 LTZ Dually Diesel 4x4 CCLB
2011 Montana 3455 SA. 6 point level up. Disc brakes. Curt Q24 Hitch
Progressive EMS. Valterra tank valves. Sailun G637 tires. ARP fridge control. All led lighting. Mor Ryde IS
beeje is online now   Reply With Quote
Old 07-10-2020, 07:43 PM   #6
BB_TX
Montana Master
 
Join Date: Oct 2006
Location: McKinney
Posts: 5,603
M.O.C. #6433
I agree with you that it should be zero or infinite ohms depending on position. Can’t think of any reason there would be a resistor on a cutoff switch, especially a low value resistor. Would be interesting if you could find that and maybe get an explanation.
__________________
Bill & Patricia

2007 3075RL
2012 F350 SRW CC LB FX4 6.7
BB_TX is offline   Reply With Quote
Old 07-10-2020, 09:10 PM   #7
Carl n Susan
Site Team
 
Carl n Susan's Avatar
 
Join Date: Oct 2005
Location: Carmichael - CA
Posts: 4,484
M.O.C. #4831
Quote:
Originally Posted by Turtle-Ham View Post
Thanks for the reply; you said pretty much what I expected. I'm still measuring 13.7V at the switch on the converter side; the battery side of the switch is down to 12.2, so it's slowly discharging.
Yup it looks like the switch is dead

Quote:
Other than the fuses, there's no breaker that I've found from the converter to the battery, self-resetting or otherwise. The fuses inside the converter all checked good, so that narrows it down to the switch itself, and a replacement is due in early next week.
Behind the batteries on the wall are two red plastic covered self-resetting breakers. See the picture below. The left one is notorious for being undersized. Read this Thread to learn much more than you ever wanted to know about it and what to replace it with.

https://www.montanaowners.com/forums...ad.php?t=76037



__________________
Carl (n Susan) Youngren
There is more to life than fuel mileage.
2012 Montana 3700RL Big Sky Package towed by a 2015 Ford F350 6.7L PSD 4WD CC LWB

Carl n Susan is offline   Reply With Quote
Old 07-10-2020, 09:43 PM   #8
sourdough
Seasoned Camper
 
Join Date: Mar 2020
Location: Lamesa
Posts: 85
M.O.C. #26010
Quote:
Originally Posted by beeje View Post
Like Carl said, I have owned 3 Rv,s with that switch and have NEVER moved any of them. Short of a bad connection, I don't see the switch being your issue.

I've owned several RVs as well and never had a bad disconnect switch...and never switched one off or on. The last unit began all kinds of 12v problems; intermittent, problematic. Ran my issues during failures to the disconnect. I know my way around voltage and ran it down. The switch was faulty...no doubt - VOM nailed it. Found a new replacement at Tractor Supply and all was well. It's a simple switch depending on a simple connect when flipped...and they are cheap. In an RV they aren't premium components and can/will fail....we just have to find them.
__________________
Danny and Susan wife of 52 years
2019 Ram Laramie 3500 6.4 4x4 CC 4.10 SRW
2020 Montana High Country 331RL
sourdough is offline   Reply With Quote
Old 07-11-2020, 02:48 PM   #9
Turtle-Ham
New Member
 
Join Date: Jun 2017
Location: Box Elder
Posts: 7
M.O.C. #19992
I saw the two red breakers behind the batteries, but didn't know they were breakers. Now that you've pointed them out, I pulled them out of circuit to eyeball them and IDed the one on the left as a 20A made by Pollak and the right hand one as a 30A from Shortstop. They both tested OK out of circuit.

But as has become well known info, Keystone - or any other manufacturer for that matter - isn't likely to cough up any wiring diagrams or other related info, so how do I know what these two should be rated at?

If one of them had actually failed, I'd just replace it with the same rating of course, but it would be helpful to know from the manufacturer what the specs actually call for.

Meanwhile, I'm trying to trace the other four wires attached to the the right hand self resetting breaker. (One is purple, one brown & white, and one 12 gauge red, all going into the bulkhead; the fourth runs into the hose assembly above the leveller pump.) We'll be sitting here for a while, so we don't need the levellers right now, but something's draining the batteries, so I need to the figure out that puzzle piece as well.
Turtle-Ham is offline   Reply With Quote
Old 07-11-2020, 02:53 PM   #10
beeje
Montana Master
 
beeje's Avatar
 
Join Date: Oct 2015
Location: westminster md
Posts: 1,576
M.O.C. #17894
As far as I know propane detectors CO2 detectors level up systems slide systems are all connected directly to the battery. So even if the factory disconnect switch is turned off they could still draw current. The only way to stop the draw permanently is to install a disconnect switch on the negative battery terminal or disconnect it
beeje is online now   Reply With Quote
Old 07-11-2020, 02:57 PM   #11
Carl n Susan
Site Team
 
Carl n Susan's Avatar
 
Join Date: Oct 2005
Location: Carmichael - CA
Posts: 4,484
M.O.C. #4831
Quote:
Originally Posted by Turtle-Ham View Post
I saw the two red breakers behind the batteries, but didn't know they were breakers. Now that you've pointed them out, I pulled them out of circuit to eyeball them and IDed the one on the left as a 20A made by Pollak and the right hand one as a 30A from Shortstop. They both tested OK out of circuit.
I will bet dollars to doughnuts those breakers are 50 Amp, not 20A (particularly that left one as it powers the hydraulic pump which can draw upwards of 100 amps) or 30A.

As for the wires, I am guessing one goes to the propane sensor, another powers the Level Up brain, and a third is the 12V charge line from the truck.
__________________
Carl (n Susan) Youngren
There is more to life than fuel mileage.
2012 Montana 3700RL Big Sky Package towed by a 2015 Ford F350 6.7L PSD 4WD CC LWB

Carl n Susan is offline   Reply With Quote
Old 07-11-2020, 03:23 PM   #12
Turtle-Ham
New Member
 
Join Date: Jun 2017
Location: Box Elder
Posts: 7
M.O.C. #19992
Very interesting!

The self-resetting breakers, both were clearly marked: "Pollak 20A" on the left, and the right breaker showed "Shortstop 12V Z31 30A". If the levellers can pull in excess of 50A, then it's no wonder the breaker pops, and I'm surprised it hadn't been a problem before; the plot thickens!

WRT the other wires, I figured one of them went to the pump; the truck charge wire shouldn't be too difficult to trace and verify. We rarely use propane, so I'll leave that one for last!
Turtle-Ham is offline   Reply With Quote
Old 07-19-2020, 02:32 PM   #13
bcrvman
Seasoned Camper
 
Join Date: Jun 2020
Location: Qualicum Beach
Posts: 75
M.O.C. #26399
Quote:
Originally Posted by Turtle-Ham View Post
Very interesting!

The self-resetting breakers, both were clearly marked: "Pollak 20A" on the left, and the right breaker showed "Shortstop 12V Z31 30A". If the levellers can pull in excess of 50A, then it's no wonder the breaker pops, and I'm surprised it hadn't been a problem before; the plot thickens!

WRT the other wires, I figured one of them went to the pump; the truck charge wire shouldn't be too difficult to trace and verify. We rarely use propane, so I'll leave that one for last!
Keystone has advised to upgrade the hydraulic pump self resetting breaker from 50A to 80A.
You seem handy with the VOM, just clip to ground in V mode and with the + probe work along from the battery post to the cutoff switch. First unplug shore power so the battery is the only power source. If the disconnect switch does not show 12+ volts on both sides the switch is either tripped or defective.
__________________
2018 Keystone Montana 3811MS
2017 Ford F450 diesel dually
400AH Battle Born Lithium Batteries, 4x170 watt solar
3,000 watt hybrid inverter with 120A charger
bcrvman is offline   Reply With Quote
Old 07-19-2020, 04:02 PM   #14
paulinbaja
Montana Fan
 
Join Date: Feb 2014
Location: Chico
Posts: 239
M.O.C. #14041
Take either connection off the switch. Now land it with the other wire on the other side if the switch. Now that the batteries are charging go buy a new switch and install it.
paulinbaja is offline   Reply With Quote
Old 07-19-2020, 05:35 PM   #15
phillyg
Montana Master
 
Join Date: Aug 2015
Location: SWFL
Posts: 532
M.O.C. #17801
Yes, replace the left self-resetting breaker with an 80a re-settable breaker, as indicated in the written Lippert advisory (see their website). Since you're full-time, there's no need to turn off either battery switch, but if you ever want to, a simple knife switch at or near your negative battery terminal is the easiest way to totally disconnect the batteries.
__________________
2016 Montana 3711FL
2005 Ford F350, 6.0 diesel, short bed
Demco Hitchiker Auto Slide hitch
phillyg is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Powered by vBadvanced CMPS v3.2.3
Disclaimer:

This website is not affiliated with or endorsed by Montana RV, Keystone RV Company or any of its affiliates. This is an independent, unofficial site.


All times are GMT -6. The time now is 05:34 AM.


Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
×