Help - mystery battery draw in the middle of a 10 day dry camp!

[mbvell]

Dry Camping this week and our fully charged batteries died completely in 2 days. Had to buy two new batteries and now they are draining quickly (hours) with nothing on except the refrigerator.

We've done the following tests:
1. Disconnected the ground from the battery and measured The voltage across the battery negative terminal and ground - Nearly a 12 V draw!

2. When battery disconnect is disconnected, there is no draw.

3. With battery CONNECTED, pulled Every fuse one at a time, and the 12 V draw remains.

I'm very confused and concerned since we still have five days left on our trip. The only thing I can think of is that the Trailer brakes or somehow engaged, but that would mean with the battery disconnect in on there would still be a voltage And we are measuring only millivolts.

Suggestions?

Many Thanks.

mb

[mbvell]

Oh.....maybe the 12V measured is not really a big deal? I measured only 1.5 mA which would make sense given that the CO/LP detector should draw about that much. Measured only 2ish amps when I turned the fridge back on - we have rigged up a small fan (less than an amp?) in there to reduce ice build up.

[Acableguy06]

Are you looking and Volts or Amps? Checking Volts will not tell you where the draw is from. It will only show you what voltage you have. Now in a case with an extreme draw the voltage will rise if you remove the source of the draw. However, on a small draw "battery dead after 2 days" you wont see much if any voltage rise.

[Acableguy06]

Also 4 amps of continuous draw over two days (48hours) would be 192 amp hours. Depending on how many amp hours your batteries are rated for there is your dead batteries.

[mbvell]

Cable guy,


Thanks for the quick response. In my update post, I mentioned that I measured 1.5 mA.

Question: should I be measuring the amps between the pole and disconnected ground or just across positive and negative poles with ground connected?

Q2: should I repeat the "Remove one fuse at a time" Test while measuring amps?

Thanks!

MaryBeth

Corrected: 1.5mA not amps!

[mbvell]

Originally Posted by Acableguy06

Also 4 amps of continuous draw over two days (48hours) would be 192 amp hours. Depending on how many amp hours your batteries are rated for there is your dead batteries.

I am measuring only 1.5mA, not amps. (I got it right in my first post).

I'm running two group 24 12v batteries in parallel

mb

[Acableguy06]

Originally Posted by mbvell

Oh.....maybe the 12V measured is not really a big deal? I measured only 1.5 mA which would make sense given that the CO/LP detector should draw about that much. Measured only 2ish amps when I turned the fridge back on - we have rigged up a small fan (less than an amp?) in there to reduce ice build up.

you stated 2 ish plus about 1 amp? then any other parasite loads. I just used 4 amps to give you a rough idea where your batteries are going. This does not include any lights you are using in the coach. Everything adds up.

I do not know what volt meter you have to tell you how to use it. However, you will probably have to move the red lead to another port on the meter and switch your setting to the dc amp setting then you would measure across the + side of what you ar working on. remove the cable from the battery and put one lead on the batt. and the other on the terminal you just took off. Most meters only have a 10-20 amp rating for amp draw in this configuration. From the sounds of it you are not very familiar with using a VOM and should seek some help from someone that is.

[Brother Les]

If you have pulled each fuse one at a time and checked for a voltage drain, and have not found the bad line, then it would seem that you have a 'grounding' between the battery and the fuse box. This should shorten your search for the grounding/ chaffed wires.

Also if you dry camp very often, invest in some solar panels (generator) to help keep your batts up.

[mbvell]

Sorry for the confusion cable guy. I mis-stated amps in my original posting. The built in CO monitor shouldn't draw Very much at all and the refrigerator fan is .12 A according to the advertisement for it on eBay, where we bought it.

The voltmeter I am using switches automatically from milliamps to amps and is in DC mode so that's not a problem. And I do know how to measure with it, but apparently I don't know how to properly record what I measure! LOL.

So. I measure ~1.5mA and 12.5 V across the poles when ground is connected (when the fridge is on and the fan is running). I measure slightly less between the disconnected ground wire and the negative pole under the same conditions (fridge, CO), ~1.4mA and 12v. I am positive of the readings, just trying to make sense of it.

Thanks,

mb

[mbvell]

Originally Posted by Brother Les

If you have pulled each fuse one at a time and checked for a voltage drain, and have not found the bad line, then it would seem that you have a 'grounding' between the battery and the fuse box. This should shorten your search for the grounding/ chaffed wires.

Also if you dry camp very often, invest in some solar panels (generator) to help keep your batts up.

Thanks, Brother

I'm wondering why, if there was a short between the batteries and the fuse box, the voltage measured between ground and the neg poke would go to zero. Sure you are right, just trying to recall my 30 years-ago circuits class!

And yes, I have solar. I went with goal zero for the plug and play ease, but have regretted it ever since. I have had 3 charge controllers, and all three have had shorts between the negative and positive alligator clips. I'm selling it all and looking for a better system!

mb

[Acableguy06]

Originally Posted by mbvell

Sorry for the confusion cable guy. I mis-stated amps in my original posting. The built in CO monitor shouldn't draw Very much at all and the refrigerator fan is .12 A according to the advertisement for it on eBay, where we bought it.

The voltmeter I am using switches automatically from milliamps to amps and is in DC mode so that's not a problem. And I do know how to measure with it, but apparently I don't know how to properly record what I measure! LOL.

So. I measure ~1.5mA and 12.5 V across the poles when ground is connected (when the fridge is on and the fan is running). I measure slightly less between the disconnected ground wire and the negative pole under the same conditions (fridge, CO), ~1.4mA and 12v. I am positive of the readings, just trying to make sense of it.

Thanks,

mb

Based on these numbers, if this is at the battery and this is your only draw then you have no short. However, I do not see it possible to only be drawing 1.5mA with frig., fan in frig, and co detector. IMO

Furthermore, you still have not said how many lights you were using in the 2 days that killed your battery. Did your water pump run any? Do you have a sound system and did it run? Do you use an inverter for anything? Were the old batteries full charged before you left? Also you stated 2 group 24 batts. how many amp hours are they? Are they marine batteries or true deep cycle?

[KyDan]

With battery connected-
Set your meter to Amps/milliamps.
Pull fuses ONE at a time and place the meter probes across the fuse
holder terminals.
Your meter replaces the fuse and measures the amps being "drawn" by
what ever is on that circuit.
Check each circuit this way and write down any current you see.

Don't worry about voltage right now.
You are trying to find the current in amps in each circuit.

If your fridge is a 3 way power MAKE SURE it is on LP ONLY mode.
If your fridge has an "environmental" heater in the metal between
the freezer door and the fresh food door you should know that heater
is 12v and it will suck your battery dry quickly.
Many fridges have a little switch at the top of the door opening for this
heater. SHUT OFF that switch!!
A few models have the heater and no switch to shut it off.
That sucks but there is a work around IF you determine you have
the heater and no switch.
You don't care about a little condensation between doors- especially when
you're boondocking.

[mbvell]

CableGuy,

1.5 mA doesn't make sense to me either....puzzled that one over for most of my nights' dreams and can't figure it.

Some additional info:

* 2 old group 24s were 100Ah each, new ones are 140. Not sure on marine v deep on the old, and it's pouring outside right now or I would check, but I think they are deep cycle marine.
* all of our interior light are LED, and we run them sparingly when we dry camp (an hour a day total for all lights)
* water pump is turned on as needed - total run time per day of at most 10 minutes. We sponge bathe or sun shower on long dry camp trips
* furnace is on the fritz, so despite the fact that we are camping at 9000 feet in a lot of rain, it hasn't run once. :-(
* we do have a sound system but haven't powered it up thus trip.
* we did use the 12v outlet to charge an iPhone the first day, but have since switched that fx to our goal zero power pack.

mb

[mbvell]

Dan,


I'll make those measurements as soon as I Can get myself to get out of bed. BRRRR.

Re: the fridge, it is only 2way - LP and 110 so it shouldn't be drawing much from the batteries. We have the switch on LP only now, too. And there is no environmental heater either, just the 3rd party fan we installed in the fridge.

The only other thing I can think of is that a short in the Goal Zero charge controller or alligator clips fried the first set of batteries (wouldn't surprise me given the shorts in the first two controllers). If the new batteries we bought yesterday weren't QUITE fully charged, that might explain the drop from FULL to 2/3 on the built-in battery monitor in the camper AND our panic that something was eating battery power. I SHOULD have insisted that the salesperson throw the batteries on their tester before we walked out the door, but you know how it goes with hungry kids and husbands, worry Bout digs left behind at camp, etc...

mb

[SteveBingham52]

Not sure if you have Internet access but this link will help you calculate how long batteries will last. Also if you do not have deep cycle batteries but have car batteries once you drain them completely a few times they really lose a lot of amp hour capacity. You can't tell much by measuring voltage though. You need current draw. If you are only drawing two amps a 60 amp hour battery should hang two weeks. If you draw more of course it goes down. For us using the pump to shower and flush speeds the discharge up.

http://www.batteryweb.com/pdf/invert...sizing_faq.pdf

[Brother Les]

You need to find out which line is the parasite line.

Pull all of your fuses at one time.
Next pull your negative cable on the battery.
Attach your meter with one on the neg post of the batt and one on the neg cable going to the camper.
Do you have any amperage going through the meter?
If yes, then you have a grounding problem from the positive line from the batt to the fuse box.

If no amperage then reconnect your neg post.
With all of the fuses out.
One at a time, use your meter and go from one side of each fuse to the other. All should have no amperage going through them with all systems are off. The fuse line that has amperage going through it will be the one that is 'grounding' or has some type amperage 'pull'.

With what it seems that you have and what you are doing,two fully charged deep cell batts should last you the whole time you are there and that would be with out the solar cells. imo You have a parasite somewhere imo.

I am no professional electrical person and this is only imo.

[Brother Les]

If you have car 'jumper battery cables', take each of your new batts and charge them with your truck. Do not have them hooked up to your camper when charging up.

[mbvell]

10. HH T - 0

9. Radio 1.5mA

8. Antenna boost - 0

7 a/c. -

6. LR - 0

5. Refer-Furn - 1.25mA

4. Bath - 1.5mA

3. Kitchen - 1.02 mA (led light on)

2.porch - 0

1. Empty - 1

[Brother Les]

Do you have zero pull of amperage when all of the fuses are pulled and checking for amperage between the neg post on the batt and neg (pulled) cable going to the camper?

[KyDan]

On board battery "monitors" that have LEDs that show
full
3/4
1/2
1/4
are notoriously in-accurate. (although I do use mine but with caution.)

Measure battery voltage with a digital meter.
Do the measurement with light or no load.
Don't go by the measurement if you've just taken it off a charger
in the last few minutes.
Rough rule of thumb- battery voltage at 12.0v is 40% charge remaining.
see chart here bottom of the page-
Trojan Battery Company

Above all-