Something drawing down house batteries

[DGrantwilsoncreek]

Our 2014 Airstream interstate’s house batteries are continuously drawing amps. I have taken it to a service shop and he is stumped regarding what might be causing this. When we are dry camping with the only thing being used is a light, we have to run our generator the next morning as the batteries are down to 50%. The batteries have been checked the they are ok. We do have a 50 watt solar system but it wasn’t workin as well and I found that it was wired wrong at the panel. Any suggestions would be appreciated.
Thanks
Darek

 

[Gary RV_Wizard]

You didn't mention the size (amp-hours) of the battery bank or the light(s) in use. Or the age & condition of the battery(s). 50% battery overnight isn't really unusual or terrible.

There are surely more than lights drawing power, e.g. LP or CO detector, circuit boards for fridge & water heater, thermostat display, some gauges, etc. All tiny power draws, but they add up. And is there an inverter powered on? They draw some amps even if no devices are turned on and pulling power from the inverter.

Battery age/condition is important too. A battery that had a 100 AH capacity when new might easily be down to 70-80 AH after a few years.

 

[jubileee]

Don’t happen to have a battery disconnect solenoid in the system do you? Ive seen the contact plates in those become corroded and create
an amazing amp draw that’s amazingly hard to find.

 

[theLegionWithin]

12v lead acid/agm? probably replace the batteries if they're more than 6 or 7 years old - you may want to get a larger battery too, like a group 31/group 34 size.

50 watts of solar seems a bit underpowered, presumably you're using an alternator as the primary charging method (or a generator)? if you've got the roof space look into a larger panel.

 

[DonTom]

Our 2014 Airstream interstate’s house batteries are continuously drawing amps.

Were you able to prove that with an ammeter with everything off?

It would be a good idea to first put a 12V lamp in series and see how bright it is. If it lights up brightly, use it instead of the ammeter. Too much current can blow out the ammeter.

It's nice to have numbers. For an example, to be able to say something like "everything I can find is off and I still have a 2.6 amp draw."

Without numbers, we have to guess, such as a bad cell in a battery or aged batteries. Sometimes even a new but defective battery.

-Don- Auburn, CA

 

[Mark_K5LXP]

Wonder and guess, or measure and know. A $10 meter from harbor freight will tell you exactly what the draw is, and from there you can isolate the circuits in the trailer to the specific draw. Battery merit can be easily measured with a simple test. Your service shop sucks, this is an academic exercise.

Mark B.
Albuquerque, NM

 

[DGrantwilsoncreek]

Wow thanks for all of the input I really appreciate it. I currently have two 55ah optima batteries that are a little over a year old. With everything off except monitors, detectors and so forth it was drawing anywhere between 1.7 and around 1. I did charge the batteries and let it sit overnight for about 20 + hours and it was down to 50% battery according to the monitor. Is this about right or do i have something drawing down the extra amps? Thank you so much for your help.
Darek

 

[Mark_K5LXP]

With everything off except monitors, detectors and so forth it was drawing anywhere between 1.7 and around 1.

So is the goal to reduce this to zero for storage, or are you just wondering what "ambient" power draw should be? Generally, with everything off the power draw should be very low just to operate a CO detector or battery monitor.

do i have something drawing down the extra amps?

"Extra" implies more than you anticipate or want. Your monitor is indicating your batteries are discharging. Whether it's intended or not, or excessive or not is up to your expectation or requirement. "Monitors" can account for some of that, measuring them would establish that level. If the current is still more than you expect then you're in for isolating circuits to find the draw. The most direct way is to use an ammeter to monitor the current, then turn off DC breakers or pull fuses to see which ones affect the draw, and determine what equipment is connected to those circuits.

Mark B.
Albuquerque, NM

 

[Kirk]

There are several factors that can play into the problem. Have you checked to be sure that the electrolyte is at proper level? If electrolyte is low that will have a very negative effect on the time to discharge. If you have a 1a continous discharge that will mean that your battery loses 1 amper hour each hour. If you have a group 27 battery with an 80 AH rating that should last of 40 hours to 50% or 20 hours at a 2a constant discharge rate. With 2 batteries of that rating they should last close to twice as long. Your batteries should have an amper hour (AH) rating listed and that is the place to start.

 

[Mark_K5LXP]

I currently have two 55ah optima batteries that are a little over a year old

Optima's are AGM's, no electrolyte to check.

Mark B.
Albuquerque, NM

 

[Contributor]

Something is on. On my trailer, the parasitic draw of the CO monitor and radio is 0.1A.

Do as Mark said, pull each fuse one at a time until you find the culprit. I had a similar situation earlier this year and couldn't figure it out. I found a light on in the pass through storage space. I couldn't see it until I opened up the exterior access door.

 

[DGrantwilsoncreek]

Thanks everyone for the input truly appreciated.

 

[jims94vmx]

It seems even lighted ac switches and thermostats can use some battery power as well....

 

[jubileee]

Once again, do you have a solenoid battery shut off? They draw current BEFORE the fuses.
I had a draw down once that about drove me insane. Was the solenoid.

 

[DGrantwilsoncreek]

I will check the solenoid. Thanks

 

[Ernie n Tara]

Note that 12V lights can easily draw 1 Ampere or more. Are you sure they are all off?

Ernie