No 12V Power Without 110V

srolfe · 03-24-2015, 04:18 AM

I have a 2014 Thor Vegas. I currently have no power from my house batteries unless I am hooked up to shore power. Once I disconnect shore power I no longer have any 12V, except cab items. I thought that maybe the house batteries are bad, although they are fairly new. I checked the batteries and they are charged. I wonder if the disconnect switch is stuck and this is the problem? Anybody ever had that problem?

FW28z · 03-24-2015, 09:42 AM

There should be a battery connect switch somewhere on your coach. Depending on your model, this switch is often located in the step well on the rear panel. Other Vegas owners will be able to help you with the precise location.

Typically there will be a LED on that panel. If the LED is on, the batteries are connected to the system. If the LED is off, they are disconnected.

And when you depress the switch, you should hear a "clunk" somewhere in the coach, which would be the contactor connecting the batteries.

JamieGeek · 03-24-2015, 11:24 AM

There is no LEDs to indicate if the house battery is on or off.

The disconnect switch is right next to the door. If you are standing outside about to take a step into the coach look for a switch on the kitchen panel to the left of the door under the pop up shelf that is labelled "Use" and "Store". It is a momentary contact switch; simply press it in to the "Use" side and you'll hear the clunk as the relay clicks on (the relay is located inside the black box in the drivers side outside storage compartment).

FW28z · 03-24-2015, 11:32 AM

That is what I love about these coaches... no two units are alike.

srolfe · 03-24-2015, 05:11 PM

Pressing the disconnect switch does nothing

FW28z · 03-24-2015, 05:22 PM

That would probably be the problem. The contactor may not be engaging. Not sure if there is a fuse on the coil of the contactor or not.

JamieGeek · 03-24-2015, 05:34 PM

Your problem likely lies in the fuse panel in the drivers side front storage:

Diagram:

Circuitboard:

(I had posted these images in another topic around here along with a document I found about that circuit board including diagnostics...sigh if I find it I'll post a link..)

Ah, found it:
http://www.thorforums.com/forums/f8/...-box-1203.html

Larry · 03-24-2015, 05:47 PM

There's a reset switch for the batteries located inside the battery compartment on the left side. Small box with a reset button. Try that if not a fuse issue.

Larry · 03-24-2015, 10:22 PM

The reset button is the small, red one near the battery on left side.

srolfe · 03-25-2015, 01:06 AM

cannot see it, is it near that rectangular block?

Larry · 03-25-2015, 02:02 AM

Sorry about the picture quality. Yes, it is on the rectangular block close to the battery. Left side after lifting the battery compartment cover. Small, red, reset button that disconnects/reconnects the 12v coach batteries.

srolfe · 03-25-2015, 02:23 AM

I am hooked up to shore power, my house batteries show 12.3 volts, which i understand is not fully charged. does charging take place with the disconnect switch in standby mode?

FW28z · 03-25-2015, 02:42 AM

I wouldn't think the charger would be connected if the battery is in standby as usually everything is disconnected from the battery at that point.

Typically a lead acid battery is 100% charged at 12.6V, 50% charged at 12.2v and fully discharged under 12V. However, the voltage test is only accurate on a disconnected battery at rest for at least 1 hour with no load or charger connected during the rest period (24 hours rest is better, but 1 hour gives you a reasonably accurate reading).

12.3V to me indicates a somewhat discharged battery.

Battery charge voltage is typically around 13.5V or so. If your DC converter was hooked to the battery and on shorepower, you should measure 13.5V or higher (depending on the converter charge mode), which would indicate the shorepower converter is maintaining a charge on the battery.

JamieGeek · 03-25-2015, 11:33 AM

In addition, if you start the engine you should see about 14.4 V on both batteries.

sporte77 · 06-09-2015, 03:01 AM

This is where the battery controller is located on a Thor Four Winds 28Z - it's behind the circuit breaker panel in the rear bedroom. There's a 5 amp fuse - that when blown - will not allow you to connect your house batteries. So you would only have 12V available if you were plugged into AC power. I blew my 5a fuse when changing out the new disconnect switch.

magicbus · 10-04-2015, 05:16 AM

Experiencing similar problem with our 2014 axis.]Even with all batteries fully charged, engine and generator do not always start. All electrical terminals are clean. Cant figure out. Wondering if solution would lie in reset switch, as described here or relay circuit board. If a fuse is blown, the problem would not be intermittent. Afraid to take it out on a trip wondering if it will completely die on us. Problem is intermittent

sporte77 · 10-04-2015, 03:31 PM

Quote:

Originally Posted by magicbus

Experiencing similar problem with our 2014 axis.]Even with all batteries fully charged, engine and generator do not always start. All electrical terminals are clean. Cant figure out. Wondering if solution would lie in reset switch, as described here or relay circuit board. If a fuse is blown, the problem would not be intermittent. Afraid to take it out on a trip wondering if it will completely die on us. Problem is intermittent

Sounds like you are on the right track - suspecting a "reset switch" or even a circuit breaker. I've seen 20a-30a circuit breakers on RV's be intermittent. Sometimes depending on temperature or humidity - they can work, or not work. Check all the CB's and see if any don't have that fresh, solid "click" to them. If they are sloppy, loose or don't have a defined click -they are suspect.

Sam

magicbus · 10-05-2015, 12:16 AM

Thank you

charlie2380 · 08-04-2016, 12:16 AM

I thought I had a similar problem so I am reaching out for help. I emailed Thor directly through the owners link on their website Monday and still no word.
My RV was connected all last week while I worked on the body (clear coat faded very bad and oxidization was really bad). anyways....
when I disconnected shore power the batt was dead. Replaced battery.
(it was tested and advance auto said it was beyond charging...walmart battery)
-- replaced with a new one. Still nothing worked. Took it back since walmart batteries are notorious for not working. so Second battery was good and tested. still nothing!

I started trouble shooting fuses and relays. found a relay was super hot so I replaced it. Nothing.
All I hear is the battery switch clunk from use to store. LED panel does not show any battery power.

Found two 40A fuses (under dinette seat where fuse panel is) blown. SO i found where my problem starts. I continue to blow new fuses.

Can anyone lead me in the right direction on what the two 40A fuses power? The panel does not say nor does the RV manual. all other breakers are labeled and identified.

I will add some pictures soon if necessary.
Any help is very much appreciated.

Tom N3EQF · 08-04-2016, 02:18 PM

Quote:

Originally Posted by charlie2380

Found two 40A fuses (under dinette seat where fuse panel is) blown. SO i found where my problem starts. I continue to blow new fuses.

Can anyone lead me in the right direction on what the two 40A fuses power? The panel does not say nor does the RV manual. all other breakers are labeled and identified.

I will add some pictures soon if necessary.
Any help is very much appreciated.

The 40A fuses are there for protection in case the battery connections are reversed (positive and negative leads on the wrong battery posts).

You may also like: