Two 12V batteries flat in 7 hours, normal?

We have a new 2014 Bighorn 5er that has two 12V Excide deep cycle Marine type #27 batteries. This unit has been plugged into shore power since we took delivery in April either at home or at F/H campgrounds. This past weekend we did four nights of dry camping without any type of H/U.

Night #1 power usage consisted of: one hour with two LED lights on for reading, running of Dometic 12 CF double wide fridge, LPG detector operating, LPG furnace ran through three cycles due to outside temperature at 50 F, water pump ran for three toilet flushes. In the morning the RV battery indicator panel read 1/3 full. I ran the Honda generator for 6 hours throughout the day and evening and tested the batteries ½ hour after turning off the generator. Volt meter reading was at 15.2 and 15.1 for the two batteries.

Night #2 power usage consisted of: NO LED lights (used Coleman lanterns for reading), running the fridge on LPG, running the LPG detector, furnace NOT used, water pump used for two flushes, but would not operate after 4 A.M., at which time the battery indicator panel showed the batteries were empty. I used generator again to fully charge both batteries to 14.7 and 14.8 volts.

Night #3 and #4 usage was the same as night #2, again with the generator used each day to recharge the batteries. The batteries went FLAT from 9 P.M at night to 4 A.M in the morning which is 7 hours. No lights or other appliances were being used.

Is it possible that the Dometic fridge running on LPG is the cause of the batteries going flat? Should I have the dealer replace both batteries? Is this nornal for two 12V batteries to run flat in 7 hours with running of fridge on LPG only?

Thanks for your thoughts on what I should do.

Lakeside

Night #2 power usage consisted of: NO LED lights (used Coleman lanterns for reading), running the fridge on LPG, running the LPG detector, furnace NOT used, water pump used for two flushes, but would not operate after 4 A.M., at which time the battery indicator panel showed the batteries were empty.

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Sounds pretty abnormal. Either the batteries are defective or something else is sucking power.

I gotta ask. Have you ever checked the electrolyte (water) in the batteries?
If not, you may have destroyed the batteries.
I do not have dual batteries, but I have made it through the night with one battery in 30° weather running the furnace all night.
I do think you have a problem and should have the batteries tested.

Peace
Dave

Yep, you've got a problem. Last summer we volunteered for the Forest Service in WY. By mid Aug. we were getting temps in the mid to low 30's overnight. Only had 50 Amp power for 4 hrs in the AM & again in the PM, we also only had 1 battery. It would last all night with the furnace going. Before we left it was getting colder so I bought another battery & installed it, just in case.

Hi Lakeside,
First, I wouldn't trust the monitor panel to be a "perfect" indicator. Second, You really can't read the 2 separate battery voltages, charged or discharged, with your voltmeter as they are connected in parallel. Third, your reading of over 15 volts (after letting the batteries rest) concerns me. I wonder if your converter has been overcharging them?

You should have about 210 Amp-Hours capacity in a perfect world. I can easily see 3 to 5 amps of parasitic draw from the LP/CO Detector, refrigerator, hot water heater, and furnace control boards. At 7 hours, that's 35 amp hours, or 17% of your capacity. You basically had no other loads on nights 2-4.

I'm suggesting that you should get your batteries load tested, and I'm betting you'll find that one or both are mostly deceased. Remember that if one is bad, it becomes a load on the other. The question remains as to why. Could just have been a defective battery, but I'd check the convertor voltages very carefully through all 4 modes of operation.

Good luck.

Water in both batteries at the bottom of viewing hole and compeletly covering all the cells.

Had a mechanic load test each battery after 72 hour "rest" peroid for the batteries and both tested perfect.

The only item I really left running was the fridge and the LPG dector. I had the fridge set to "LP" mode. Could it be possible that the fridge did NOT switch to LP mode and was running off AC mode and drawing down the batteries?

This is a new unit (2014) and my dealer has no idea what the trouble could be. Like my original post stated, I was hooked up to shore power all summer with no issues. This first 4 day dry camping trip is when the syatm failed with MINIMAL 12V usage. I am very handy with general repair, but this one has left me baffeled. Thanks for your help.

Lakeside

Could it be possible that the fridge did NOT switch to LP mode and was running off AC mode and drawing down the batteries?

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If you have added an inverter to convert 12V battery power to 110V AC, yes it could have. If you haven't added an inverter, no it couldn't.

Keep in mind your fan and the control board in the refrigerator runs on 12 volts even when running on propane. Don't think that would draw a battery down overnight though.

As Rick mentions - the 15V is concerning - is this from the monitoring panel? A digital volt ohm meter on the battery posts is best - a fully charged, resting battery (no current in or out for 30 minutes) should read about 12.7 to 12.8V.

Your 2014 bighorn should have a Progressive Dynamics converter and it may be a 9200 series (link) - if so it is a (4 stage) intelligent converter/charger which when it is on boost mode (14.4V charging) will bring the batteries back to near 70 to 80% capacity in 6 hours when shore power (or generator) is present. It takes over 34 hours to bring a battery back to 100% with an intelligent charger. That is why you get less capacity in the second and third day when boon docking and running a generator for 4 to 6 hours.

From my measurements in the past, the fridge on LP draws about 0.6A or 0.8A (@12.8V) when firing the LP heater (increased current to hold open the LP valve). In one day that would be 14-20 Ah.

Hope this gives you some information to ponder.

Brian

We recently boondocked overnight on a hot, muggy night. Ran the fantastic fan in the kitchen until about 5:00 am (about 8 hours) along with the CO2 detector and our double-wide Norcold fridge running on LP. As it was our first official overnight without any AC power and we don't have a generator, I was a little concerned since we had lowered our front jacks to stabilize the rig. Wasn't a problem. Jacks went up and we still had plenty of power remaining. That was on one 12V battery.

I'd venture that you've got some type of draw there that isn't fully obvious.

The 15 volt reading is either an error or something grossly wrong - maybe discharged batteries in series? The 2 batteries should be connected in parallel: that is the + terminal connected to the + terminal; the - terminal connected to the - terminal. I assume the 15 volt reading was with the charger OFF. Like what was said before the maximum out of the charger charging should be 14.4 volts. The electochemistry of a lead-acid cell from basic chemistry results in 2.2 volts per cell. A "12" volt battery has 6 cells (think like flashlight cells) which adds up to 13.2 volts per battery. Batteries can be charged at slightly higher voltages (i.e. the Progressive Dynamics PD9200 "Boost" mode @ 14.4 volts), but only can produce 13.2 volts from the electrochemistry of the battery.
You might disconnect the wiring between the batteries and measure them individually.

I would try a different volt meter to see if the 15v reading was a discrepancy with the volt meter. As a general rule it takes 1 volt extra for every 6 volts when charging to overcome internal battery resistance so you need a charging voltage of 14v for a 12v battery and 28v for a 24v battery etc. give or take a little.

I had a similar issue with a previous trailer.....it would kill the battery in about 3 hours.......after as much diagnosing as I could do without totally taking the electrical system apart I found it was a simple fix that was easy to overlook and easy to occur........the trailer break away switch had been pulled and the brakes were engaged 100% drawing what I would think is a large amount of power killing the battery whenever there was no charging taking place........plugged break away switch back in and the problem was solved......just another item to check.

OP er here. The batteries have been out of the 5er and setting on my wooden top work bench for 7 days without any type of charging going on. I used the same digital volt meter and got readings as follows: 12.2V & 12.3V.

The brake connection was hooked to the switch and NOT activating the emergency brake syste. Good place to check. Thanks.

There must be another draw somewhere that I can't figure out yet. I appreciate the ideas on what to check from you good folks.

The 15.2v readings I got was directly after the Honda 2000 generator had been running for three hours WITHOUT any rest time. I did not realize things needed time to rest.

I will recheck the batteries in a week or so and see what I get for readings. I can't for the life of me understand what could have flattened both batteries over a 7 hour peroid. At 0400 A.M. not even one 12V light would work in the 5er. Things were really FLAT. Thanks for all the great help.

Lakeside

Lakeside,

I noticed a prior post of yours:

WOW did I ever get a surprise. In back of the switch panel there is a bank of 5 relays and on first look I observed several different colored wires going in every direction. I also noticed that whatever colored wire was going to a particular relay, brown, red, green, blue, and orange the same colored wire went to (or should have gone to) the corresponding switch on the control panel. Brown, red, and green wire/relay/switch combinations were perfectly matched. The blue hot wire from the blue relay was connected to theH/W switch and the orange power wire from the orange relay was connected to the YETI cold weather switch. Here in lies the problem. When the H/W switch was turned on, the YETI cold weather package was operating. When the YETI switch was turned on the H/W heater had power and was working perfectly. All I did was swap out the blue and orange wires and reconnect them to their appropriate switches and the whole system functioned correctly.

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It's a striking coincidence that you would have found 12V relay wiring problems, made some corrections, and now have something sucking power out of the batteries. I'd recheck the relays. You may have something like the Yeti heat tape turned on when you think it's off. You might have to check operation with selected fuses pulled to narrow down the problem.

Good find Dan, that may shed some light on this.

My suggestion from personal experience. Our previous sob trailer couldn't hold a charge either. We took it back to the dealer - they told us we didn't know how to use the camper (we've only been rving for 15 years). After the 3rd set of batteries in 2 seasons we took it back again and said to check everything - 2 weeks later they could find nothing. 3 more sets of batteries (remember - deep cycle batteries DO NOT like to be fully discharged and we couldn't stop it). We'd go to bed 3/4 charged and wake up empty. I read by flashlight and god forbid we used a furnace. Camping world refused to replace batteries any more, blaming it on the trailer. Dealer blamed it on us. Absolutely maddening. One weekend in the high mountains we met a rv tech on a small vacation. Told him our problem and he offered to check it out for us. He went through everything and could find nothing, but at the end of his inspection , while standing in the water closet, he thought he'd do a last check of the fuze panel. Knowing everything was off, he checked the panel and...power was on in 2 places. Turns out the tank warmer's (there were 2) were wired in reverse. We thought they were off (we're in az - don't need them) because the switch said so - but they weren't. A change in the wiring and that set of batteries worked for the next 3 years till we sold the unit. Even removed the generator as we didn't need it either. Good luck- your answer is out there.

Mrsfish and danemayer.....you may have hit the nail on the head of this beast. Prehaps my "Yeti" tank heater package IS drawing the 12V power. I will speak to my local Heartland Tech and run this idea by him. Thank you all so much.

Lakeside

lakeside said:

Mrsfish and danemayer.....you may have hit the nail on the head of this beast. Prehaps my "Yeti" tank heater package IS drawing the 12V power. I will speak to my local Heartland Tech and run this idea by him. Thank you all so much.

Lakeside

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The heat tape on the fresh water line should be 12V. The tank heating pads should be 110V. But the relays are probably all 12V.

I don't think this would be a large enough draw to kill 2 batteries overnight but.....
In the 'fridge there's a 12V heater strip around the door to prevent condensation. Some units have a switch to turn this heater off, others do not.

I have a Fluke multimeter with a 20A ammeter mode. My no-load idle current is .07A and that's the hard-wired propane detector. I have dual G27 batteries, LED lighting, and an upgraded IOTA converter. Morning battery voltage (no furnace) is 12.3-12.4 volts and I run the generator 2-3 hours a day to top them off.