Newbie Battery Question

[Jwestman]

I've got a 2012 Flying Cloud 25. I put the batteries on store when we pulled out of the campground for home. Once here, I left it over night still attached to my Jeep. Today the Jeep battery is dead. Does something in the trailer draw juice from my car battery if the trailer batteries are off or do I have an electrical problem with the Jeep?

[Silver Otter]

Hmm. . . I'll be interested in the replies. I remember draining my truck battery trying to run the furnace while connected only to the truck on cold, cold day. Won't do that again.

[Gene]

I believe recent model trucks and cars do not supply power to the umbilical when the engine is off. Of course, some companies may omit that because the switch for that may cost a dollar or two. It could be a coincidence or no automatic disconnect switch.

J', once you get the Jeep battery charged, use a 12 v. tester to check the charge line at the receptacle to see if it hot when the engine is off (and on, might as well do both). Which is the charge line? Sometimes it is marked on the cover of the receptacle or it is in the owner's manual; you can check online too.

Gene

[idroba]

My 2012 Jeep Grand Cherokee has a constant 12 volt supply from the Jeep to the trailer as long as it is plugged together. So, if you had the trailer battery disconnected (I don't understand the new AS electrical systems) you may be able to operate things in the AS from the Jeep battery, and run it down.

[Scott J-24]

Well, I know that on our AS if the switch is set in the store mode and you connect the generator or shore power, the stitch is overridden. I was also told by someone the same was true when connected to the TV. The PO told me to disconnect the TV from the AS if you stop for the night on a long road trip because it could drain the TV battery. So... I always pull the plug and leave a sticky on the rear view mirror so I don't forget to hook back up.

[Silver Otter]

Originally Posted by Scott J-24

I always pull the plug and leave a sticky on the rear view mirror so I don't forget to hook back up.

Hey, there's a another neat idea picked up on the fab. forum! Thanks.

[Protagonist]

Originally Posted by idroba

My 2012 Jeep Grand Cherokee has a constant 12 volt supply from the Jeep to the trailer as long as it is plugged together. So, if you had the trailer battery disconnected (I don't understand the new AS electrical systems) you may be able to operate things in the AS from the Jeep battery, and run it down.

Even though the house battery on your trailer is disconnected, your outside trailer lights are still connected as long as the trailer is plugged into the tow vehicle. Including your clearance lights, taillights, etc.

Not all vehicles are equipped with a timer to shut off your headlights when you kill the engine. And it's possible that even if you have a timer, the trailer lights may not be on the timer. If the trailer lights somehow stayed on while the unit was parked, that would explain the battery drain.

[Silver Goose]

Most vehicles equipped with a factory tow package use a relay that is picked by the ignition circuit to provide voltage on the charge line at the trailer connector. Older systems used a diode block to accomplish the same isolation for the vehicle's starting battery. I'm not familiar with a Jeep, but measuring the charge line at the open connector at the rear of the Jeep will tell you if you're getting 12v constantly, or only if the key is switched on. If present, the relay could be stuck in the on position. Your Jeep manual may mention the relay, or a dealership mechanic could certainly tell you if one is installed. It is typically in the fuse box under the hood. Otherwise, you may have to remember to unplug the umbilical for those overnight stops where you don't have shore power. Just remember to plug it back in before hitting the road in the morning.

[blkmagikca]

What we used to do is install an isolator diode kit that prevented the trailer from draining the tow vehicle battery. When I had my LY moho, it came with a diode isolator which never really worked, causing me to have to rely on jumper cables from the car I towed behind.

This thread is prompting me to check to see what the setup is in my Dodge Ram. I should check it out.

[Jwestman]

I've got to get a 12 volt tester tomorrow and check out the feed from the Jeep. In the meantime, I'm trying to figure out what could draw down the battery overnight. Everything that I can see has been shut off.

[TBRich]

J'... When I read your original post I wondered why you would switch the battery disconnect switch to "store" when towing.

As I understand it, the battery disconnect switch isolates the trailer batteries from the converter, and the reason the switch light remains on even when set to "store" if you are connected to shore power or a generator is that the shore connection or generator is providing the charge to the 12-volt system and the 110 system through the converter...but it is not charging the battery (because it's been isolated). Frankly I don't know if that applies when you are connected to the tow vehicle. I'll have to check that the next time we are hitched up.

The only time we put the battery disconnect switch in the "store" position is when we are actually storing the trailer, all systems are off, and we want no 12v power to the trailer...which is rarely the case for us.

I have read that the LP gas detector and jack are hard wired to the battery but I would not think that is enough of a draw to run your tow vehicle battery down over night. I truly don't know if it matters, but when we overnight somewhere and leave the truck hitched, we do not leave the umbilical cord plugged into the tow vehicle ... and we run off trailer battery power. It seems to me that if the tow vehicle battery was drained overnight there must have been an additional higher-demand draw being made on it...the frig, perhaps? Was your sound system on?

I'll be interested to hear what you find out.

[JamuJoe]

Interesting thread. We generally leave the trailer connected to our Jeep Grand Cherokee while dry camping, unless we're using the Jeep, and have never had a rundown of the Jeep battery. I have the factory tow package.

I do throw the Airstream battery disconnect switch to 'store' mode in order to disconnect the Parallax single stage charger when on shore power for an extended period, in order to prevent overcharging my batteries. The converter remains powered to provide 12v in the trailer. My three stage solar controller then provides the float voltage to my batteries.

[mefly2]

To be safe, we unplug the umbilical when parked overnight / not in motion ... some TV sockets disconnect power to the TT circuit, some do not. If you "pull the plug" you will be able to isolate the issue. Our battery disconnect does not interrupt AC power to the converter, so we don't leave AC connected for extended periods when we are not actually using the AS. YMMV

[Silver Goose]

Originally Posted by TBRich

...
As I understand it, the battery disconnect switch isolates the trailer batteries from the converter, and the reason the switch light remains on even when set to "store" if you are connected to shore power or a generator is that the shore connection or generator is providing the charge to the 12-volt system and the 110 system through the converter...but it is not charging the battery (because it's been isolated). Frankly I don't know if that applies when you are connected to the tow vehicle. I'll have to check that the next time we are hitched up.
...
I have read that the LP gas detector and jack are hard wired to the battery but I would not think that is enough of a draw to run your tow vehicle battery down over night. I truly don't know if it matters, but when we overnight somewhere and leave the truck hitched, we do not leave the umbilical cord plugged into the tow vehicle ... and we run off trailer battery power. It seems to me that if the tow vehicle battery was drained overnight there must have been an additional higher-demand draw being made on it...the frig, perhaps? Was your sound system on?

I'll be interested to hear what you find out.

TBRich has it right about the function of the Use/Store switch. It disconnects the coach batteries from the from the 12v distribution bus in the trailer. There is a two-fold purpose for this: It prevents the batteries from being overcharged by a single stage charger if left plugged into shore power for long periods of time as someone else mentioned. It also reduces the drain on the batteries in storage, however as TBRich noted the LPG detector is hard wired to the coach batteries providing a minimal but constant load on them. The tongue jack and breakaway switch are also connected to the coach batteries 100% of the time, but unless the light on the jack was left on, neither of these draw any current from the batteries, and then only from the coach batteries.

The indicator light on the Use/Store switch is misunderstood by many. The only time the light will be OFF is if the the batteries are in the Store mode AND there is no other source of 12v power to the trailer; that is, no shore power and no power coming from the umbilical. The light being on simply means there is 12v power available in the trailer, not the position of the switch. This is also a way to verify the isolator relay in the tow vehicle is working... Disconnect the trailer from all power and switch the batteries to Store, the light should go out. Plug in the umbilical. The light should remain off, then start the car and the light should come on.

None of this explains why you had a dead battery in the Jeep the next morning. The Use/Store light is an LED so that drain is minimal. As TB mentioned, the sound system is a good bet, I find mine on a lot and it goes unseen as it is in a cabinet. Do you have the subwoofer option? What about an inverter? Do you have an outside compartment with a light fixture, some models do. Consider the possibility that it was not the trailer at all. A weak battery and a glove box light left on over night might do it. A basic troubleshooting strategy is to divide and conquer. Use your new meter to determine if the car battery isolation is present and working to either rule out or suspect the trailer then go from there.

[Jwestman]

The mystery continues and I suspect a couple of you folks have isolated the issue.

I tested the receptacle on the Jeep. There is no power with the ignition off and there is power with the ignition on. I tested across the positive and negatives located at 1 and 7 o'clock and left the lead on negative at 7 and tested across all the others. Nothing except at the positive 1 o'clock position with the ignition on.

I checked all interior lights on the Jeep and nothing was left on. In the trailer everything was off except for the radio with subwoofer does light up whenever power is restored. (Has to be shutoff again after a power restore). Nothing else was on. No storage lights, not the frig...nothing.

I talked to the RV service center and they said to unplug the rig when parked because it will draw from the vehicle if the house batteries are put in the store position. I also wonder if the trailer breaks draw some power though now I'm really guessing.

Bottom line: it is probably best to disconnect power from the TV when not in use.

Thanks for all your comments!!

[Gene]

The subwoofer does draw some power as it does not have an off switch (some may have it under the dinette seat and it is relatively inaccessible). I installed a switch and leave it off a since a subwoofer seems silly in a trailer, but I'm not 20 years old. The TV antenna booster, if left on, also takes power. And the battery disconnect may not work properly.

The igniters on the fridge, furnace and water heater also take power when in propane mode.

This does not explain the Jeep dead battery so long as the charge line was not hot when the Jeep was off. Have you had the Jeep battery tested? A door may have been enough ajar to cause lights to be on, but you wouldn't know if you didn't notice the door was slightly open and the light wouldn't be on to tell you when the battery died.

Gene