Constant Battery Draw

jhuffman · 06-12-2018, 08:40 PM

Hi,

I noticed a few issues with the 12V electrical system on our new to us TT and was hoping to get some input. I have a fair bit of marine experience as well as low voltage electrical experience, but this is our first RV. Our trailer has one house battery that handles all load and we do not have a generator. When reconnecting the new battery terminals, I noticed an arc. I checked to make sure there were no lights on and measured the current from the battery's positive terminal to the main house cable supplying the trailer. 4.5 amps! Lights are off, and after looking at the distribution panel, I can't see that anything is on other than the radio/CD player that apparently comes on when the battery is connected. My next step would be to pull each fuse one at a time and check for a change at the meter. But I thought it would be worth asking, is there something that should be drawing 4 amps that I don't know about? I know there is a CO2 detector, but I would think that would be a nearly nonexistent load.

I haven't dug super deep at this point but I did pull off the cover of the electrical distribution panel that is located below the refrigerator. I saw nothing that seemed out of the ordinary except perhaps the converter that appears to be fairly low end. On my boat, I have an altogether different battery setup including a Xantrex battery monitor which provides accurate measurements of voltage, current draw, and overall battery condition for 3 banks. It was not inexpensive however, and I'm not sure it would be worth the money and effort for the TT. Does anyone have any experience with a battery monitor in their RV?

The other thing that I think seems odd is that when I connect the 7 pin trailer connector, this places both the TV and the TT batteries together. I get that we want to charge the battery while driving, but this means that I need to remember to disconnect every time we stop - or run the risk of pulling down the TV battery if power isn't available. Is this pretty standard for pulling a trailer?

Otherwise, we really like the trailer. It was used very little (3 times I believe) and the entire trailer looks brand new.

Thanks for any suggestions or comments!

notanlines · 06-13-2018, 02:17 AM

Jonathan, your F-150 will not drain after the engine is shut off. I can't speak for the Suburban.

Pull Toy · 06-13-2018, 02:36 AM

^^^ What Jim said.

If you check the truck end of your 7 pin, you'll find that the only time it is "Hot" is when your ignition is in the ON position. This keeps your start battery from going dead while hooked up, and parked.

As you mentioned the best way to troubleshoot is to pull fuses to find the culprit, There is some small parasitic drain from your radio clock and channel memory, CO detector, hard wired smoke alarms etc...

Good Luck,

**flybouy** · 06-13-2018, 03:48 AM

There is a parasitic drain on the battery but at that amperage I'd guess something was left on. The fridge control panel is 12vdc, the hot water heater uses 12 v when in gas mode and the television antenna has an amplifier that's low voltage as well. That's a list of some of the low voltage appliances. Your lights are low voltage as well as anything like an in command center (remote control system for slides, levelers, awning, arc.) As others stated pulling fuses is the best way to isolate drain but you will always see some arching when connecting battery cables due to parasitic drain.

HANGAR · 06-13-2018, 10:27 AM

I would recommend your first modification to be a battery disconnect. I like to completely isolate my batteries from the trailer in between trips. There will always be a small draw on the 12VDC side when the unit is sitting idle not being used. I agree your draw seems to be significant and I would troubleshoot to find what's sucking the current, but I'd still recommend a disconnect be installed when you have the time.

jhuffman · 06-14-2018, 07:12 AM

Thanks Jim,

I tested the F150 and unlike the suburban, it automatically disconnects the 12V pin when the engine isn't running. For now, I will disconnect the trailer plug when I'm using the suburban and not in use.

Thanks!

ChuckS · 06-14-2018, 07:16 AM

Looked at a few CO2 detector specs and average current draw is .75 amp so gotta be some other DC items like fridge, stereo, etc drawing that current

jhuffman · 06-14-2018, 07:18 AM

Steve,

I did test the F150 and it does disconnect when the engine is not running. But the suburban has that pin hot even with the key removed. After looking through the fuse diagrams, the trailer is wired correctly. At the fuse block on the Suburban I can see where the trailer wire is landed, and it has battery voltage all the time regardless of whether the trailer is connected or not, or whether the engine is running. Seems strange to me but for now I will just disconnect the trailer wire when parked.

I will have time this weekend to pull fuses and see if I can find what is drawing the 4+ amps.

Thank you for the response!

jhuffman · 06-14-2018, 07:20 AM

Thanks Flybuoy, I will spend some time this weekend going through the electrical and hopefully I will find the culprit. I'll post what I find.

Thanks!

jhuffman · 06-14-2018, 07:28 AM

Hangar, I agree. Seems like a disconnect would make a lot of sense. I'll need to figure out the best location to install one. Too bad there isn't a wiring diagram for these trailers, I need to make sure that wherever it is placed, it disconnects the entire load which is probably going to be very near the battery.

Thank you for the reply!

**JRTJH** · 06-14-2018, 07:29 AM

If your Hideout has a Dometic 2652/2852 refrigerator, there is a "door heater circuit" that is "constant on"... The purpose is to prevent condensation around the door gasket. On the "upgraded models" (2662/2862) there is a switch under the top, eybrow control panel to disable that function if you're dry camping. No such switch on the "economy models".... So, if the refrigerator is on, you'll have about a 2.5 amp draw in that heater circuit to go along with the CO detector, propane detector, radio memory circuit and the TV antenna booster. All of them on at the same time would probably add up to around 4 amps.

I'd guess (definitely a WAG) that your reading of 4 amps is about right, given all the "phantom draws" that are present. They are the reason most people who park their trailer in a storage lot will come back to a "completely dead battery" after a week or so. It's more than an inconvenience, it's a "death sentence" to the battery/batteries on the trailer. Repeated discharge below about 60% for most "marine/RV batteries" will destroy the "internals" in one season. That's why either disconnecting the battery bank or installing a "true disconnect switch" is important for battery longevity.

jhuffman · 06-14-2018, 07:32 AM

Thanks Chuck. Even after I eventually find the cause of the 4+amp draw, I think that a battery disconnect is in order for when the trailer is just sitting in the yard. It will be interesting to see how much draw there is after I find the big culprit.

Thanks!

jhuffman · 06-14-2018, 08:15 AM

John, thanks for the info. Crazy design! Seems like a system that is designed with a constant load like that would come with a battery disconnect from the factory or dealer. I'll check on the refrigerator tonight, but definitely will get the battery disconnect installed.

Thanks again!

Steve/ · 06-14-2018, 08:46 AM

I went thru the same thing, here the numbers I had.
OK I disconnected the door header and here are some number. Before the mod with fridge on 1.65 amp. With mod and fridge off 0.215 amp, (parasitic drains), Fridge on 0.475 amp. This is on a RB195 (24 ft ) 2017, Dometic DM 2652 fridge.

notanlines · 06-14-2018, 01:12 PM

JHuffman, generally you won't find me coming to the defense of manufacturers of our RV's but in the case of the battery disconnect I'm afraid it is in order. Smoke detectors and carbon monoxide alarms necessarily remain active for safety purposes. I learned early on that in large boats, auto-bilge pumps also remain active even when the battery disconnect assures the owner that both batteries are disconnected. Manufacturers simply cannot take on the responsibility of a complete disconnect. Believe me, their liability insurance carriers will demand it be that way.

Steve/ · 06-14-2018, 05:24 PM

Quote:

Originally Posted by notanlines

JHuffman, generally you won't find me coming to the defense of manufacturers of our RV's but in the case of the battery disconnect I'm afraid it is in order. Smoke detectors and carbon monoxide alarms necessarily remain active for safety purposes. I learned early on that in large boats, auto-bilge pumps also remain active even when the battery disconnect assures the owner that both batteries are disconnected. Manufacturers simply cannot take on the responsibility of a complete disconnect. Believe me, their liability insurance carriers will demand it be that way.

I do not think that holds water, you can have a cut off switch that cut off everything but those safety items. But with a 1.7 amp parasitic drain the safety devices will have no power to them after a week. I would think after a month with the battery discharged it is a bad battery. Seem like it would be better with cutoff switch. It seem to me if it was a problem they would all have their own battery, the smoke detector in my house runs for a year in my house on it's own battery. Since the manufacturer does not supply a cut off switch that the safety devices are hot. The owner has no chose to put in a cutoff switch ( or pull a wire off the battery) that cut off everything. How is that better?

Steveo57 · 06-14-2018, 05:48 PM

I have a 2018 Cougar 22RBS and the disconnect switch opens the DC feed to the distribution panel and kills all the DC loads fed off it. The only things that have power are the add ons like the slide motor, stabilizing jacks, and tounge jack that have separate feeds right off the battery.

The smoke detector and CO monitor are powered by 9 volt batteries and the propane leak monitor is dead with the disconnect switch off.

notanlines · 06-14-2018, 05:51 PM

Let me get this straight: You're second-guessing 7 major RV manufacturers and a huge basket-full of insurance companies because your battery goes dead before you think it should. I simply told you why it is wired that way. Install a simple disconnect in the battery compartment and all is good.

**sourdough** · 06-14-2018, 08:31 PM

Quote:

Originally Posted by Steve/

I do not think that holds water, you can have a cut off switch that cut off everything but those safety items. But with a 1.7 amp parasitic drain the safety devices will have no power to them after a week. I would think after a month with the battery discharged it is a bad battery. Seem like it would be better with cutoff switch. It seem to me if it was a problem they would all have their own battery, the smoke detector in my house runs for a year in my house on it's own battery. Since the manufacturer does not supply a cut off switch that the safety devices are hot. The owner has no chose to put in a cutoff switch ( or pull a wire off the battery) that cut off everything. How is that better?

I'm not sure what you are advocating RV manufacturers do. Cut off federally mandated safety devices because you can't/won't take care of business or you don't think you should have to....and the manufacturer should? A full battery cutoff is painfully easy and inexpensive - if you own an RV, get on the ball and do it....it's not the manufacturers fault. Jim nailed it.

**JRTJH** · 06-14-2018, 08:53 PM

I can't count the number of members here who say, "I didn't know that worked that way"....

Why did I just type that statement? To illustrate what would happen after the first family died in a Keystone RV from carbon monoxide poisoning if Keystone provided a "shutoff switch" for the CO monitor. Or you can ask yourself what "greedy lawyers" would do if there was an explosion in an RV from a propane leak and killed the family in that trailer, burned down the adjoining trailers and disfigured 4 children from scarring due to burns.

The public outcry would be heard "loud and clear" that Keystone was responsible for the outcome because they provided a means to bypass the safety devices and the "poor hapless owner" was a victim because he didn't understand the danger of bypassing the safety device.....

That's also the reason that you can't watch movies on the LED screen in vehicles while it's in motion. Sure, there are "unlock adapters" that you can buy and install, but don't look for Ford, GM or Chrysler to put them on the option list for your next truck. What owners do to bypass safety devices is "on the owner" it's not "on the company".....

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