12 Volt power concern

[SDFiver]

Hi All,

Just joined the forum after purchasing a new 2019 Bighorn 3760 EL.

Already coming to ask for help from those who know all. Had something happen on our second hookup and tow that has me wondering if its right or not. Hope it isn't.

Our first tow was from the dealer to a site where se spent 2 1/2 weeks. All went very well. When we went to leave that site we disconnected shore power, went inside and turned on the inverter using the switch on the control panel so the fridge would have power during the trip. I then used the Level-Up to complete hooking up.

During a pit stop along the way we discovered that we had no 12 volt power to the water pump or any of the interior lights. The fridge was still on so no major concern at that point.

When we disconnected at our destination a couple of hours later I unhooked and leveled using the Level-up and the wife put out the slides while I plugged into shore power. At that point we still had no 12 volt to the interior lights or fantastic fans. The fridge was still on.
I remembered that during our PDI a few weeks earlier that the demonstrator mentioned a reset button on the inverter. When I pushed it in we suddenly had our 12 volt back.

Is this normal? I hope not since we really want our 12 volt stuff to work during pit stops enroute.

Thanking in advance, Carl

 

[jbeletti]

Hi Carl. Welcome to the forum and congrats on your new rig!

Your issue seems a bit odd. Sounds like you had DC power for the jacks and the inverter. With that much power, I'm unsure why you didn't have any DC lights or water pump.

You say you reset the inverter, yet it was on, inverting battery power to AC power to feed the refrigerator at the time.

Note that the inverter does not produce or inhibit DC power. It does use DC power to make AC power for the refer.

Can you clarify any of this or give us other information? We're here to help, just want to clarify a bit.

 

[SDFiver]

Hi Jim,

Thanks for the fast reply. You're up late. Thanks on the congrats. We've got some other comments on this rig but this is the most important.

Yes, we had power to the hydraulics when we arrived and before we plugged into shore power. We were able to unhook, level up and run all three slides out on battery power. Just no juice to anything else that was 12 volt. (I'm guessing the hydraulics and it's controls are wired seperate from other 12 volt stuff) Yes, I know the bedroom slide is not hydraulic.

Yes, the inverter was on when we arrived. (We've RV'd for 20 years so we understand inverters and converters quite well.

The inverter was still on when I pushed the button on it's face. As soon as I pushed the button the 12 volt came on. That makes no sense since it shouldn't have had any effect on the 12 volt system at all. It's a wiring and hydraulic line nightmare in that front compartment area.

Could I have unplugged and switched on the inverter in the wrong order upon departure from the last site or does it matter?

I'll be at the Grand Canyon all day tomorrow so will check this thread upon return.

Good night, Carl

 

[danemayer]

This is a bit puzzling as pressing the reset button on the bottom of the refrigerator's dedicated inverter in the front compartment shouldn't affect the other power path that supplies 12V DC to the interior lights and pump.

I've attached a block diagram that shows how these pieces go together.

Based on your description, the only thing I can see as a possibility is that one of the 12V DC mini-circuit breakers tripped for some reason, got stuck open, and reset when you hit the inverter reset button. That's an unlikely scenario however.

But if I assume a wiring change at the factory, making the power route a bit different from what's in the attached diagram, there could be something we don't understand at this point.

I'd suggest you check that both battery cutoff switches are actually ON.

Also, look for the buss bar near the batteries where there's a row of mini-breakers covered by a red rubber boot. One of them has a teeny-tiny reset button on the bottom. Try pressing that. I've attached some pictures that may help you locate the breaker and reset button.

 

[CDN]

Hello,

I would check the grounding block. There might be a loose connection here that under load of the Invertor opens up but when this load is removed goes low in resistance and everything else starts to work. There is generally a common ground back to the coach fuse blocks.

The block is bottom right behind the batteries, hard to get too. They spray the block with a coating to prevent corrosion.

The 12 VDC positive side through disconnect for the jacks and coach power would be working based upon jacks working.

Brian

 

[SDFiver]

Hi Guys, Thanks for the suggestions.

I started checking it out again a couple of minutes ago.

Yes, both batteries were turned on and all connections were tight. First thing I did was turn off the shore power. When I did everything went dead except for the hydraulic system and the bedroom slide. I turned on the inverter via the switch on the control panel. It came to life just like it should. All 12 volt stuff was still dead.

I then turned shore power back on and everything came to life three minutes later when the surge protector finished checking the power out. 12 volt stuff came on line also.

Checking the mini-breakers per Danemayer's suggestion showed that only one of them had a reset button and it appeared to be out further that expected. To verify this was the culprit I killed shore power again which caused a total blackout. When I pushed that reset button all the 12 volt stuff came on so you nailed it Danemayer! Way to go!

No idea what caused this breaker to pop or if it will again but at least I know exactly where to look.

Thanks for all the help! Take care,

Carl

 

[mlpeloquin]

Make sure you always turn the breakers off when disconnecting. Also if you power it up at home, you need to put a breaker or switch for the power source. The sparks make by pulling the plug live, weather it is 120V circuit or the 240V will cause the 12V breaker to pop. No all the time, but it will. Don't as me how I learned that.

 

[SDFiver]

Hi Mlpeloquin,

No problem Brother. I always make sure all the shorepower box breakers are off before plugging in or unplugging. Learned that many years ago.

Thanks for the reminder.

Take Care, Carl

 

[JMP]

I just shut-off the main breaker prior to disconnecting from shore power, and then after connecting to shore power turn on the main breaker. Are there other circuit breakers that [should] be turned off prior to disconnecting from shore power?

 

[SDFiver]

JMP - By my statement I meant that I make sure the 20, 30 and 50 amp are off before I plug in or unplug. Just seems easier to me.

 

[Chainsaw]

This is a bit puzzling as pressing the reset button on the bottom of the refrigerator's dedicated inverter in the front compartment shouldn't affect the other power path that supplies 12V DC to the interior lights and pump.

I've attached a block diagram that shows how these pieces go together.

Based on your description, the only thing I can see as a possibility is that one of the 12V DC mini-circuit breakers tripped for some reason, got stuck open, and reset when you hit the inverter reset button. That's an unlikely scenario however.

But if I assume a wiring change at the factory, making the power route a bit different from what's in the attached diagram, there could be something we don't understand at this point.

I'd suggest you check that both battery cutoff switches are actually ON.

Also, look for the buss bar near the batteries where there's a row of mini-breakers covered by a red rubber boot. One of them has a teeny-tiny reset button on the bottom. Try pressing that. I've attached some pictures that may help you locate the breaker and reset button.

Thanks Dan

I had checked for the reset as described herein. found nothing. I had lost my 12volt when we left home, I confirmed the fridge worked on AC so decided to leave as we only had a 3 hour drive and I could work on it here.

Then I read several posts re read yours and turned off the power at the post. There it was, pressed and the lights came on. Fridge said Lo DC. I checked the batteries and they were at 11.2. Normal for us is 13.2. I use my CPAP on inverter so I plugged into the truck, Message went away.
Thank you for all of the manuals you supply.
Don