Isolator Change Issue

[chollenback]

Hey guys, I went ahead and swapped out my isolator (Model - Power Sure 1202) 3 stud (1 main and 1 alternate battery). It was straight forward (or at least I thought it was. I changed it out becasue it was 25 years old and I was getting some weird things so one of the FMCA members suggested changing it. I turned off all breakers, turned chassis battery off, unplugged from house, turned off invert and turned off chassis power. I changed out isolator (only 5 wires - not to hard). I went ahead and plugged it into my house and it tripped the house breaker over and over again. I can here the transfer switch click and then pop the house breaker. I went ahead and swapped it back to old one and it i doing the same thing (I thought maybe new isolator was bad).I went ahead and turned on inverter and it powered the items I needed. 

Is there a reset switch somewhere? What am I missing here?

 

Edited July 18, 2018 by chollenback
Modify text

[kaypsmith]

When you say house breaker, do you mean the 120 volt house breaker? The isolator should be only 12 volts DC, #1 is usually going to the chassis battery/batteries, #2 usually goes to the house battery/batteries, "A" should be wired to either alternator, or charging source if yours is marked like this. You quoted 5 wires, usually only 1 to each bank as they are normally paralleled at the bank, not the isolator, unless using the studs on the isolator as a junction point.

[dickandlois]

Chollenback,   Should be straight forward. The only thing that would or should cause an issue is if the positive and negative wires are wired backwards. 

You did post that the OEM unit still worked and it should still be good - over tightening could turn the wire studs and that could cause an issue ? All I can think of at this time.

Middle terminal goes to positive alternator output. Most cases and the 1202 should work that way !

The post at the sides of the center terminal - go to the battery positive terminals.

The case is setup to be a negative ground.

Do you have a meter? set it for ohms. red positive lead to the battery terminals - one at a time with the black wire to the case / chassis ground.

All 3 post should read a low resistance and almost equal ! reverse the set up and place the red wire to ground and the black one to the each post in succession. This sould give you a very high ohms reading - open circuit. 

Get that reading on all the terminals - the diodes in the unit are good 

One can do the same test with the engine running (The shorts need to be cleared)  and read 12 volts at all 3 terminals and all should read 12 volts.

Rich. 

Kay the 2 smaller terminals go to the regulator and  drawing a blank LOL

links to look at might help.

https://www.google.com/url?sa=i&source=images&cd=&cad=rja&uact=8&ved=2ahUKEwj1tZGEyqfcAhVEF6wKHfalARUQjRx6BAgBEAU&url=https%3A%2F%2Fwww.thesamba.com%2Fvw%2Fforum%2Fviewtopic.php%3Ft%3D366746&psig=AOvVaw2s98Mcj9hDzpddE_94Q0Bk&ust=1531964602131174

 

[kaypsmith]

Rich, the OP said three studs, I looked them up also and the 1202 is 3, 1202D is 4.

[dickandlois]

Thanks Kay ! That is what I thought I was reading 3 not 4 and then 5 popped up.

Rich.  just posted some options.

[chollenback]

I will do the Ohms test tonight when I get home. When I plug In reference to "my house breaker tripping" I am refering to my stick built house. Rich I hooked up the old one back up and it kept tripping the stick built house breaker as well. I have a feeling it maybe the automatic transfer switch. The reason I say this is that on way home from Canada wife started generator and turned on A/C to cool it down and I had to stop and start the generator because it would trip something and not turn on A/C. Once A/C came on my wife said that the voltage was over to the right (I have a outlet 120 V monitor and it was pegged over 120V). AFter a few minutes the power settled into the green. 

I will start generator today as well and see if what voltage is and then i will start coach and see if I get reading of 12V+ at chassis and house batteries. If I get 12V+ at both then that would tell me that isolator is working. Once  I start generator I will check voltage at chassis and house batteries as well and see if I get 12V+. If after this I will try to plug back into m stick built house plug and if it works then it may be the ATS. Does this sound like a good plan?

When I do Ohms test is there anything I have to do (i.e. plug into stock built house, turn on RV etc.,) 

Thanks

 

 

[kaypsmith]

I don't know what weirdness you were having that warranted changing the isolator, but changing it should have no effect on the s and b breaker unless you somehow grabbed a 120 volt wire and put that on to one of the lugs of the isolator. The ATS would be the likely suspect for tripping the house breaker, it is 100% 120volt, no 12v wires should be attached to it at all. Check for short in shore plug wiring, use your ohm meter across the legs that plug into the cg pedestal. If 30 amp, ohm across the L1 (hot) leg to neutral, if 0 to very low numbers, there is a short in the 120 volt circuit. If 50 amp (4 wires) then check L1 to neutral, then L2 to neutral, L1 and L2 are the spades opposite each other, the spade that stands off and in the center are neutral, look for the same conditions as described above. Good luck hunting, and of course, do not do this test with generator running or plugged into house current, inverter should be turned off also. 

[manholt]

When you plug into your house, what is the size of the CB & is it designated for coach only? Kay types faster than me! 

[wolfe10]

To diagnose a 120 VAC issue like yours, start by turning off the main breaker in your 120 VAC breaker box.

If the house CB still trips, the problem is in the shore power cord, wiring to ATS, ATS or wiring to breaker box.

If the CB does not trip, start turning on breakers one at a time until you find the culprit.

[rsbilledwards]

To the subject of pitching the old isolator. I was the one that told him to ditch it. These things have been the bane of Safari coaches and show up with relative frequency as going bad in all things SMC. It is my conclusion that age is a partial culprit or possibly the quality of the product of the time. Since these things can eat an alternator and cause other issues for unsuspecting owners that have not experienced such, I suggest taking the preemptive action of getting rid of the potential trouble maker. Before I figured it out while in a remote location.  I had been thru 2 new alternators. I cleaned all battery terminals and checked here and there, (wiser now). In the ensuing efforts I shorted a fuse in the ECU of the Allison. Again no luck finding what I had done sat there for two days trying to trouble shoot the thing. Called for help Turns out, luckily, the alternators were fine but I knew nothing of an ISOLATOR. With the addition of the professional help, 10 minutes and a $100 bill,  it turns out the isolator in the coach was a 130 amp with a 160 amp alternator (OEM) and shot.  May or may not have had something to do with it. The professional knew right away about the fuse. It looked good cause I checked, but when metered it was blown (much wiser now). When the similar happened in the current Panther and only 25K miles, I immediately pitched the isolator in favor of a new one. Countless stories on Safari Friends of these things dying and a meriod of symptoms.

As for 5 wires, no, max should be four if there is a sense wire to set of the regulator other wise only 3, one hot from the alt and one each the outer studs to the house and chassis batteries. I still catty a spare mechanical unit ST 85 from Napa. For me it is not necessary as I do not use the isolator any longer. It remains there as an option just cause. I took the Alt hot wire and sent it to the chassis batteries, and the house is fed by the 960 watts of solar all the time. I disconnect 1/2 of the solar when not traveling and not used.

CB Sounds like another problem to be found as suggested by the previous posters.

Additionally it would help all of those trying to help you if they knew what coach year and model is being discussed. 

 

[wolfe10]

No question,  if the IN diode from the alternator OR both OUT diodes god bad, they will destroy the alternator diodes.  Alternators have to have their B+ terminal connected to something to survive.

Many marine disconnect switches have  a label saying not to turn off the battery switch before stopping the engine  OR an "Alternator Field Disconnect"  for this very reason (turning the battery switch to off without disconnecting the alternator would blow the alternator diodes).

http://www.perko.com/catalog/battery_switches/150/medium_duty_battery_disconnect_switch/

 

http://www.perko.com/catalog/battery_switches/955/medium_duty_main_battery_disconnect_switch_with_afd/

[chollenback]

RSbilledWard - I do not blame you for telling me to switch out isolator. I think that was a good call. 

OK - Sorry for the lack of info. I will do my best to be more complete. Here we go:

I have a 1995 Safari Sahara with a 6500W Onan Gas generator with a 50amp plug (I have a tail that takes the 50amp to 30 amp and then to 120V that I plug into my house to power a light and a fan). I am confident that the isolator is working and not causing the issue and this is why:

1. I started RV and I tested alternator at isolator and it read 13.1V at idle. I went to chassis and house batteries and was getting 13.1V (I think this is telling me that it is working correctly since both are getting 13.1V an that is what I got at isolator).

2. I started generator and it took about 10 seconds for it to switch over (longer than usual). Once it switched over I put a meter to an outlet and got 134V with generator idling. I put load on it and it hovered around 126-128V. I started smelling something burning from generator so I turned it off. 

3. I then went and tried to plug my 120V cord into my stick built house and it tripped breaker again on my stick built house. 

It does not matter what plug I try to plug it into my stick built house - it stills pops it. As stated before, I put old isolator back on and I am still having same problem.

I hope this helps - Any ideas?

Thanks

 

 

[wolfe10]

10 hours ago, wolfe10 said:

To diagnose a 120 VAC issue like yours, start by turning off the main breaker in your 120 VAC breaker box.

If the house CB still trips, the problem is in the shore power cord, wiring to ATS, ATS or wiring to breaker box.

If the CB does not trip, start turning on breakers one at a time until you find the culprit.

Let us know what you find.

[chollenback]

Wolfe10. Problem solved!!! On e of the breakers that says washer/dryer or dishwasher when flipped breaks the breaker. I do not have any of those in the RV. I have left it off and all is well. Thanks to ALL of you.

Is the 134V that the generator is putting out at idle a concern?

[manholt]

In a word, Yes!

Happy, for getting rid of the other Gremlins!

[wildebill308]

3 hours ago, chollenback said:

Is the 134V that the generator is putting out at idle a concern?

Well if it is 13.4 V not 134 V it shouldn't be a problem. I would want to know why that circuit breaker is causing a problem.

Bill

[rsbilledwards]

Yes he should look into that one since it could lead to a hot coach, but that said the breaker is off.  What this means is that the end of a hot wire is exposed on this circuit. The wire nut has vibrated off and the power is trying to go to ground...badddd!!!!!! could lead to straighter hair!

As for the generator..it is producing 120 type power Bill not 12 volt power. Yes it too should be looked into.

I have made suggestions in the past in PMs that address your over all issues so I will not belabor the issue further. Go where old Safari coach info and solutions are readily available.

[wolfe10]

Agree, that at your convenience you should trace down where you have that dead short on the dishwasher/washer-dryer circuit.

As far as generator AC voltage, I would be less concerned about no-load voltage than voltage under load.  What is voltage with one A/C on?  Two A/C's on?

[manholt]

Bill E, Brett.  Maybe I'm missing something?!  Why would there be CB's and not blanks, for 2 items that OP does not have?

I suppose, it's possible if original owner, removed the WD and Dish Washer....even pre wired, would not have CB's installed. 

[wolfe10]

Very likely that the factory ran the wires, particularly if those were options-- much easier to run as part of the wiring loom than to have to run them later if the owner chose that option.

[manholt]

Brett, would they hook it up to CB's as a hot wire?

[wolfe10]

2 hours ago, manholt said:

Brett, would they hook it up to CB's as a hot wire?

Quite possibly.  And, since it appears there is a dead short, VERY likely in this case. 

So, either find where the dead short is or remove the hot and neutrals for those circuits at the main breaker box (yes, assuming the OP is safe working around 120/240 VAC).