Water Pump & Refrgerator Not Working On Shore Power

[Marty57]

I'm new to the forum but not to RV's.  Been at this for 30+ years but am stumped by this problem.  I have a '93 Tioga Arrow that I have owned for about ten years so I know it pretty well. 

Recent problem has come up with the 12V charging system to the house battery.  My battery ran down and I suspected it was the battery but it checked out OK.  Everything works with engine running or with generator running.  If house battery is fully charged (from outside source) everything works.  Shore power works until I disconnect the house battery.  At that point, the water pump and the refrigerator (Gas/AC type) no longer function but everything else continues to work. 

When I disconnect the house battery and am hooked up to shore power, I get only about 3V at the connection for the house battery.  Pulling out a bulb inside motor home with shore power plugged in and house battery disconnected, I get about 12.5V.   Over time, the house battery seems to go down and the shore power will not charge it even though shore power provided power to the lights and range hood, just the refrigerator and water pump are dead.  

With house battery disconnected I can start the engine and everything works, including the refrigerator and the water pump.  To recap, refrigerator and water pump will not work on shore power alone.  Any ideas?  I'm baffled. 

I checked all the fuses and they are all good.  There are a series of relays and a solenoid bolted to a heavy piece of steel than that steel is bolted to the chassis; I removed and cleaned up the surfaces to insure good ground and no change.  Any ideas of what this might be or how to trouble shoot this sure would be appreciated.  

Thanks,

Marty

[kaypsmith]

12.5 volts from the converter sounds very low for charging, I would expect 13.4 to at least 13.8 when plugged into shore power. Although you said that there is only 3 volts to the battery connection. Do you have a diode based, or relay based isolator? I would suspect diode based on the older model, but you can tell by looking at it, If diode based you will probably see the housing to be aluminum with heat sink finn's. The problem seems to lye between the converter and or the isolator, especially since everything works with the motor running. If the battery is marginal, the charging converter may not be able to overcome. For starters I would put in a known good battery, just borrow it from some other place and install to see if the non working units work for a while. If this works and that battery loses power, then I would try putting on a good battery charger on the battery while everything is still working. If this works then the above section of this post is probably the culprit. But again, I would not rule out a faulty battery.

Good luck hunting.

[Marty57]

Th battery was my first thought.  It's only 15 months old.  I returned it to Sears to be checked out.  They gave it a clean bill of health.  As for an isolator, I have no idea what I have or even what to look for.  I'm not familiar with an isolator in the circuit so not sure what to look for.  Still stumped but thanks. 

Marty

[Marty57]

I did a little checking and it looks like I have a relay based isolator.  It looks like the one I attached here.  I did a little testing of the isolator.  With the chassis battery disconnected and the house battery in place, there is no power to the starter.  When I press the button to connect the two batteries the engine turns over and the starter engages, starting the engine.   So I know it functions in that test.  There are three or four  circuit breakers attached above the isolator.  Could the isolator or one of these circuit breakers cause the symptoms I have found?  How can I check the circuit breakers and the isolator?  Thanks

 

Marty

[manholt]

Hi Marty,

Are the Circuit Breakers, the kind you have in your house?  Or push button, like a Ground Fault Breaker?

[kaypsmith]

With a good battery charger attached to the house battery while on shore power, does the reefer and pump work? Any circuit breaker can be tested with a VOM, disconnect the wires going to and away from it, be sure to mark where each one goes back, set the reading on the vom to read ohms, place the leads to the vom across the two terminals, the meter should read zero on the breaker, this indicates a "short" or closed circuit, on a breaker that is what you want. If these are truly circuit breakers, there should only be two wires attached and will have some type of reset as Carl is asking about. If more than two, you are probably looking at relays, especially if it is a socket type. If it is a relay, checking each one you might try removing at a time and replacing it with another with the same markings as the one replaced, then check to see if the 12+ volts has returned to the battery. Do you have any wiring schematics on your unit? Let us know if this helps.

One other thing comes to mind, while pushing the button to connect the batteries together, have someone check the pump and reefer to see if they work.

[manholt]

The battery from Sears, is it the type you distilled water too?  When Sears said the battery was good, did they tell you what voltage reading they got?  My thinking is that you have a cell that is going or is bad.

Carl 

[Marty57]

Here's some more info based on your ideas and questions above.  Below is a picture of the circuit breaker type mounted above the isolator.  They are the reset type with a rectangular button on the side.  I can only get to the top one and the button moves in and out with no determinable detente or stop  I need to pull the battery to get a better look.  The battery (distilled water is up on all cells) reads about 12.5 volts; Sears charged it and did a load test and said it was in good shape.  The pump and refrigerator works fine on the house battery when charged; the fault is only when on shore power without the house battery connected.   On shore power, there is only 2.5-3V reading at the battery terminals for the house battery with the battery disconnected.   All systems come on line correctly when I turn on the ignition with the house battery disconnected.  With the house battery disconnected and the button connecting the two batteries together held down, the pump still does not work.  Regarding a wiring diagram, no I don't have one.  The motor home is a 93 Tioga Arrow, 25' long.  I'll pull the battery and remove and check the breakers.  The isolator and breakers would be fairly easy and cheap to replace but I don't like just replacing parts shot gun style with out knowing the problem.  I'll see how these check out today.  Thanks for the help, pass along any other ideas you may all have and I'll check them out.  

Marty

[kaypsmith]

Does the battery when connected stay charged while on shore power? I don't understand why you would want to disconnect it if all works well when connected. Your unit may be wired in such a way that will not charge without the battery connected. Many smart chargers will not show any charge if no battery is present.

[Marty57]

I discovered the problem just recently.  I had been away from the motor home for a couple weeks and the motor home was plugged into shore power as usual.  I use the restroom in the motor home when I'm working in the yard, that's when I found that the water pump was not working as it usually did.   When I brought the battery in to Sears to have checked, it required a 45 minute charge to bring it up to power.  This led me to do some digging.  This is how I discovered that the shore power is no longer charging the battery and will not supply power to the pump and refrigerator even though all other appliances and lights work without the house battery connected and with the vehicle connected to shore power.  I've had this motor home for over ten years and the shore power has always provided the necessary power and kept the batteries charged until now.   This is why I'm stumped.  I just finished taking apart the wiring block that has the isolator relay mounted on it.  There is a 12V 40A circuit breaker with a re-set button on the side and two 12v 6A  circuit breakers with out  re-set buttons.  When I check them with an ohm meter they read 0 ohms of resistance, showing they are not open and allow current to flow.  I'm not sure how to check the isolator.  I am going to replace the circuit breakers and the isolator on the off chance that they are some how causing the issues.  There are also a couple if splices in wires leading into the circuit breakers that I will check out first.  I think you can see why this is so difficult to trouble shoot and why I'm looking for any and all suggestions as to how to proceed.  No need to pay over $100/hour for some of the diagnostic work if I can eliminate some of the issues first.  Time to check out the splices and replace the circuit breakers.

Marty

[manholt]

A 40A  CB on a 12V ?  I must be missing something !

[Marty57]

Here's a couple pictures of the circuit breakers and the isolator.  The isolator has a diode in the line; removed and checked and it's ok.  Soi far, everything checks out.  Ready to replace circuit breakers and isolator even though they check out.

Marty

[jleamont]

marty57, I had to reread your original post and start over. It sounds to me your convertor has failed as Kay mentioned above, your voltages are not right to charge that battery and if it was plugged in should have maintained the battery charge level.

Check the power coming into it to make sure it has 120vac coming in, if not comfortable with a volt meter working on 120 vac plug a desk lamp into the socket, or a drill and see how well it operates. Obviously this test will only work if its plugged in and not hard wired. I have replaced them both ways in the past. Reconnect the battery turn on 12v loads inside the unit, you should hear the convertor ramp up (the older style tend to be noisy while working hard) with the fan running, then recheck your voltages at your house battery and report back.

The reason everything works when the coach engine is running is the isolator is switching over from the convertor circuit to your alternator on the engine, sounds like that isolator is working as it should, you can check that also by running the coach engine and checking power at the house battery, you may have to leave the volt meter on there and keep an eye on it as some systems will switch back and forth between the chassis and house battery. Based off of the year of your unit my guess is you only have a basic convertor (aka charger), not a convertor/inverter. Its not uncommon for those to fail over time and they are not terribly expensive, the last one I bought was under $200.00.

You could also have the same symptom if you run your generator, since if its wired like I suspect it just powers up the 120v line to the Convertor also, so your house battery will not charge on generator also.

 

[manholt]

Make sure all grounds are good.  In my 97' Allegro, I only had a converter, I changed it out twice in 4 years.  I forgot about that, sorry!

[kaypsmith]

This is why I suggested attaching a good battery charger directly to the battery, as earlier stated I feel strongly that the converter is too weak to keep up with the demand. I put a 100 amp converter in my coach first, it lasted less than a year then would not keep up with demand. I replaced it with a 75 amp and has worked much better and many times longer than the first.

[hermanmullins]

Kay,

75amp worked better than the 100 amp?

Herman 

[kaypsmith]

Yep, the 100 amp seems to run too hot for the area that it is mounted in, and 75 is plenty enough to keep up. I'm sure that overheating was the culprit that caused the demise of the 100 amp. Best remedy was to go down in size, otherwise the 100 amp would need to be ducted to the outside.

[Marty57]

If it is the converter, where is it mounted?  Is it in the panel behind the house type breakers in the coach?  I did order a new isolator but I'm thinking also that it's working ok.  I bought a new 40A breaker to replace the one I have even though it checks out ok.  The two 6A seem to work ok, I wanted to change them out but I am having trouble finding a 6A 12v breaker with plastic tabs as installed.  How can I check the convertor?  I sure appreciate all the help, I'll try a few of the things above after I put things back together.

Marty 

[jleamont]

Marty, the convertor is usually located behind the fuse box, but that will depend where the fuse box is located. My last coach had the fuse box on the dinette booth in the walkway under the forward facing bench, under the cushions behind all of that was the Convertor. it should have battery cables coming off one side and a power cord or romex wiring on the other.

It will resemble this;

 

[Marty57]

My fuse panel is located under the sink, outside the bathroom.  I'll pull the cover and have a look.  Any way to check the output of the convertor?  It's putting out 12v, lights all work.  I'm assuming the pump and refrigerator are a higher amp draw and  maybe it cant handle the load?  The refrigerator is not three way, only 110V or propane; the 12v just runs the electronics as I understand it.  Thanks.

Marty

[manholt]

My Converter was like Kay, 100A and it was changed to 75A.  It was located under the sink and Breaker Box above the sink in a cabinet.

If your fridge only works on 110V, then you need an Inverter.  Converters=AC to DC...Inverters=DC to AC.  Still confused!

[Marty57]

First, the fridge.  It is not a 12V fridge; only 110v or Propane.  The 12v just runs the electronics.  My system has a 45a Converter with battery charger (see pictures below).  First picture is the label, followed by the inside of the converter than inside fuse panel and last the fuses.  I took a bunch of voltage measurements and got some very strange readings unless I have no idea how this should work.  Looking at the fuses, voltage from the white lug to fuses (L to R) 1-6 was 12.8v.  Fuses 7-9 read 3.36V.  Fuse #8 is the charging circuit to the house battery according to the label on the panel.  Next, from the red lug to the fuses:  1-6 all measured 9.48V; 7-9 0 V.  Next, the upper blue wire screwed to the top center of the fuse panel.  Fuses 1-6 read 0 V; 7-9 read 9.3V.  Measuring voltage across the three lugs also gave similar voltages:  White to Blue lug 12.8V.  Red to Blue lug 9.1V.  Red to White lug 3.6V.  Something seems really incorrect with these readings unless I don't understand how this should be working.  When I check voltage at the house battery terminals I get 3.3v, about the same as at the fuse. 

With these readings and the pictures anyone care to venture a diagnosis?  Seems to me the converter isn't working correctly; I don't understand the different voltages at the fuses but something seems to not be working correctly.  Ideas?

Thanks,

Marty

[kaypsmith]

Looking at the pictures, the one showing the fuses, if this is the 12 volt block, I can't tell the numbering scheme, but if the one further  right is one then counting to the left' notice that the # 8 to the left shows heavy discoloration which is caused by overheating, probably when the converter bit the dust. If I read your post correctly, # 8 is the battery charging circuit, and you are reading 3.6 at the lug. Position # 4 has something smaller in size than an ordinary fuse it appears to be marked either 3 or 5 is a littlefuse type 267, as noted above it. Any way my conclusions are that all lugs below the fuse should read at least 12.6 to the white lug with a near full charge on the battery.The converter should be producing still 12+ volts at 3 or 45 amps. All things as said above, I would change the converter out and the circuit board. I further recommend that you go to a 3 stage converter, this will have the charge rate automatic built into the device. There are several on the market, I purchased a powermax brand off of ebay last time and have had very good results with it. It seems that the 45 amp unit has been good for a number of years, so for the reason that if you increase the amperage, you will need to increase wire sizes to your battery, I would try to replace with exact same size. What location are you in? There are several members if close enough will be happy to assist you on a first hand basis. Except for the fact that circuit board appears to be toasted, you should be able to cut the old converter loose and rewire the new one. If you do not feel comfortable making this change, it may time to call in a tech. If you do attempt to make the change yourself, please make sure all batteries, both house and chassis are disconnected, and the shore power is disconnected, SAFETY FIRST!!!!

[Marty57]

I agree with your analysis.  I found the owner's manual for the unit I have and a trouble shooting guide.  The convertor is definitely bad.  The manufacturer makes a direct replacement upgrade kit for the unit I have.  Here's the link:  http://www.bestconverter.com/45-Amp-Converter-Replacement-Kit_p_46.html#.V5AmTY40dgF  

The site shows how to change out the unit and the pictures exactly match what I have.  I do want to stick with the same size unit, their isn't any room for a larger battery in the engine compartment.  I think it's time to order a new convertor.  I feel pretty comfortable installing the new unit, not much to it.  As to the fuse sizes and the burning, that has been like that a long time so not sure if it's related to the failure or not.  The burnt area is a 15a for lights, and the small 5 amp is for the water heater controls.  The replacement kit comes with a new fuse panel and the new controller so everything gets replaced.  Sounds like an easy repair to me.  Any known issues with this replacement unit?   If not, I think it's time to order the new unit.

Marty

[manholt]

Please keep us advised of the outcome.

Good Luck