Community Forums

CampingMutti · 05-22-2022, 04:41 PM

What is draining/killing our batteries when our rig is parked and the power switch is set to off? We own a Super-C RV and this is the second year our batteries are dead after parking our rig for the winter. We start it and run the generator once a month but this month when we tried to start the genny there was not enough juice. We brought the batteries home and charged them but after one day they were dead again.

Old-Biscuit · 05-22-2022, 04:55 PM

Parasitic draws will drain a battery within a couple of weeks

Parasitic draws......
LP Detectors, radio memories, CO detectors if connected to rv battery, etc

Do you have an Inverter?
Do you leave it ON when in storage?

**HarryStone** · 05-22-2022, 05:00 PM

You said "after one day, they were dead again". Was that sitting in your garage, or back in the RV hooked up? If just sitting in the garage, have you checked the water/acid level? If it's good, likely the batteries are toast.

THenne1713 · 05-22-2022, 10:59 PM

<<After one day... they were dead">> Was that at home, they died, or back on the rig, connected? How long did you charge, and how did you determine fully charged? Are Cargo bay LIGHTS=OFF? Inverter = OFF/ in storage mode?

TacomaJoe · 05-23-2022, 06:14 AM

Knowledge is power. For this equation you need two things. What is the capacity of the battery and what is being pulled from the battery. In my case, my parasites eat about 3/4 of an amp (about 17A every 24 hours). I have 280Ah of lithium to give me about 2 weeks with no shore or solar.

NITEHAWK · 05-23-2022, 06:28 AM

I totally disconnect my batteries from just before Halloween until today (5/23/2022) and leave my 8D in the coach--totally disconnected.
The START batteries (2) I brought home and yesterday I put them on my charger in anticipation of installing them today.
After three months of setting disconnected to anything I checked them with my gauge and they all read 12.8 or better.
When we would go south for the winter I disconnected our Ford Sportrac battery and when we got home I reconnected it and the truck started right away.
Parasitic draws will eat a battery's charge slowly but surely. DISCONNECT COMPLETELY. DO NOT RELY ON A SWITCH. All you have to do is disconnect any NEGATIVE (-) cables on the battery.

Ron Dittmer · 05-23-2022, 06:46 AM

If storing your rig for more than 3 weeks straight, I highly recommend disconnect all batteries, both for the chassis and also the house. BUT first make sure they are fully charged before walking away for extended periods.

A healthy battery that is fully charged, will remain in good condition during a 5 month Chicago winter storage cycle. I do it with my little sports car. I would remove the battery and bring it indoors, but it is very difficult to remove so I leave it in the car, but disconnected. Two years doing this so far on an older battery, and it is working for me.

Mark_K5LXP · 05-23-2022, 06:48 AM

Step one, buy and install a battery monitor with shunt. Measure the draw that's pulling down the batteries. Even if your batteries are "bad" there's something pulling current that shouldn't be while in storage. Pulling fuses is one way to observe changes in the current drawn. Consider installing a cutoff switch or lifting a cable while in storage, this removes all doubt when it comes to discharge in storage.

Step two would be to test the battery capacity. This involves a timed discharge test, not a quickie auto parts store clamp on test. You can easily test capacity at any time, while they're installed in the camper. By doing so you always know the state of your batteries and don't have to wonder if they're going south on you.

Mark B.
Albuquerque, NM

twinboat · 05-23-2022, 06:50 AM

If you weren't running the rig regularly for over an hour or more while in storage, you were slowly draning your batteries every time you ran it.

It's better for the batteries to get a full charge or just sit disconnected .

SJ-Chris · 05-27-2022, 01:52 PM

First check the water inside the batteries (add only distilled water if low).

Then put them on a charger at home for 24hrs.

Then, take them to your local AutoZone or O'Reileys, etc and ask them to test the batteries. They will be able to tell you if the batteries are good or bad.

If they are bad, replace them. I recently acquired a 23' Class C RV to add to our other RVs. It had 2 batteries (Group 27s). They were behaving "weird". I would charge them, but they would quickly be dead. I put solar on them for a few days, and it looked like they were charged, but then after just a few hours they showed 10v. I brought them to AutoZone and they tested them and told me they were bad. So I went and bought two 6v GC batteries to replace them and now everything works exactly as expected. Summary: "Weird" battery behavior is often a sign that they are bad and need to be replaced.

If they are good, then it is time to put them back in your rig and start to figure out what is drawing them down.

I'm a huge believer in having a battery monitor. You can get inexpensive ones for $50 or less (I use the Aili 300amp one that can be found on Amazon for ~$45). Once installed, you will always know what is going on with your batteries! Well worth it.

When my RV sits with "nothing" on, my battery monitor tells me that it is drawing about .3 amps (...I think, I haven't looked lately). (My RV does not have a disconnect switch by the side door like many other RVs). That means that in a 24hr period it would use up about 8AH from my battery bank. So, over time, it would drain my house batteries.

If your battery monitor tells you that you are drawing more than 1 amp, you can start pulling 12v fuses from your panel until you find the culprit. Then you will be able to figure out if it is something normal or not.

One cheap solution (assuming your batteries are good) is to install this on your battery terminals:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Then, every time you leave your RV for days you can quickly disconnect your battery.

I personally HATE dead batteries...they drive me crazy. So to solve this, I added solar to all my RVs. 100-200 watts will make it virtually impossible for your batteries to be drawn down if it is parked for days/weeks. If you add 300-500w of solar (and you are a casual RVer without power needs beyond the ordinary), you will likely never have battery issues again even when using your RV to boondock.

Good luck!
Chris