Parasitic drain kills battery in less than a day

RunningChicken

We're about to go camping and our battery life is less than a day. I've searched and looked on this forum, and have not found our answer, except perhaps there might be a short somewhere. We have a 2009 DM T@B. We noticed that our old battery could not seem to hold a charge, and so we replaced it 3 days ago with a deep cycle 27. The new battery is not holding a charge either. The only thing we know is "on" is the LP detector. We no longer have a pump, and our CO2 detector is now battery operated. The (new) thermostat has an on/off switch, as does the refrigerator. And so we have been daily tracking fuses. Pulling fuses to try to figure out what the draw is. With no fuses pulled, the draw in 9 hours is from 12.8 to 12.54. With the LP fuse pulled, the draw is from 12.8 to 12.6 (in 9 hours). With the pump fuse pulled the draw is from 12.8 to 12.54. With the "30 amp" fuse pulled the draw is from 12.8 to 12.66. And we couldn't test the refer fuse because it is on the same circuit as our battery tester. What would you do next? We have a new converter ordered (originally thought that was the culprit).

Ack- we're boon docking! we'd like at least a couple of days of life.

Thanks! 

ScottG

@RunningChicken, sorry to hear about your difficulties. The first thing I would suggest is to completely disconnect the battery, fully charge it, and repeat your test using a voltmeter connected directly to the battery. This will implicate or eliminate the battery as the source of the problem. (Even brand new batteries sometimes have issues.)

Simply pulling the main fuse at the converter still leaves a potential (however slight) for current leakage somewhere upstream. Disconnecting the battery entirely leaves nothing up to chance.

Anecdotally speaking, a drop from 12.8 to 12.66V in nine hours seems a little quick for a brand new battery, but not alarmingly so. The bigger question is whether it settles in at 12.6V, or continues to drop at a significant rate. A fully charged disconnected battery in good health should hold a no-load charge >12.5V for several days if not weeks. 

rfuss928

12.6 volts is 100% charge for a battery at rest.  Maybe there is no problem at all

BrianZ

What about checking fluid level & its specific gravity using either refractometer or hydrometer.

RunningChicken

Thanks- all good- and reassuring. Our Innova battery tester has a yellow light at 12.56 which is some of the source of our alarm. Over 20 hours, the new battery (with no fuses removed) went down to 12.42 and we stopped the test. As far as we know, the only parasite is the LP detector. After we come back from our trip we'll test the battery removed from the trailer. 

So it is safe for the battery to get to 11.9? Still in the green zone? I need to talk to my battery tester about that.

ScottG

@RunningChicken, don't pay attention to the lights on your Innova tester. These are designed for monitoring vehicle batteries and generators (alternators), so the warning lights don't really apply in this case. Go by the indicated voltage.

Battery life isn't an all-or-none thing; the more frequently and more deeply you deep cycle it (within limits) the more its life will be compromised. Conventional wisdom suggests that keeping it above 12.1-12.2V is best practice.