Battery losing power while connected to shore power

[wizardbill]

Hello, folks.  I have a situation that I am pretty sure I read about here somewhere, but I have no clue where, and after searching for about an hour, I gave up.  So, I will describe my problem.

1978 Dodge 440-3 Georgie Boy Cruise Air

When Shelby is sitting, the battery gradually loses power.  I turned the RV off, and connected to shore power.  I tested the battery and I had 12.58 V.  The next evening, I check it again.  It was down to 12.41 V.  So, I thought that was curious, and I checked the next evening.  It was down to 12.34 V.  I have no idea why this could even happen.

I am wondering, my converter might be bad, but that would just mean that it does not fully charge the battery.  If that is true, I would not LOSE power, but, I would not get charged up from shore power.

So, there has to be something else that is sapping my power.  I thought I read a way to deduce what was causing the problem, but I cannot find it.

Any help?...

Bill

[ibdilbert01]

Never owning a working converter and owning a 72, I'm not exactly sure how a 78 converter looks and what the features are, but I did a quick search on the forum and it seems some of the older converters didn't charge the battery when plugged into shore power.  Some of the newer ones it was an option to have the battery charger but it looks towards the end of the 70s it was standard equipment. 

I also read a few post where they stated their charger has a relay, and when plugged into shore power, the relay transfers all the 12 volts circuits to run directly off the converter instead of the battery.    So it sounds like to me that maybe your converter isn't working at all and it might just be a faulty relay inside your converter.   Some of these links will help you understand how its suppose to work.

http://www.classicwinnebagos.com/forum/index.php?topic=2787.0
http://www.classicwinnebagos.com/forum/index.php?topic=3687.0
http://www.classicwinnebagos.com/forum/index.php?topic=467.0
http://www.classicwinnebagos.com/forum/index.php?topic=1969.0

A GREAT site that I highly recommend you to read is:
http://www.marxrv.com/12volt/12volt.htm

And if you get into a pickle, you can always put a standard cheapo battery charger on your house battery while plugged into the shore power until you get around to repairing your converter.  I've been doing this for years.   D:oH!

[DaveVA78Chieftain]

In order to point you in the right direction, you fist have to determine what kind of setup you have.
1.  Converter with an isolation relay and no battery charging capability.
2.  Converter with an isolation relay and battery charging capability.
3.  Converter that connects directly to battery (no relay/always connected) that functions like an alternator by supplying 12VDC to coach and recharges battery (todays modern approach).

Progressive Dynamics was the primary supplier of RV converters in the 70's and 80's.  Unfortunantly PD has decided to stop repairing and discontinuing part supplies for the older converters.  However they now have posted all of the documentation for them that can be used for repair.  An overview of PD's converters from that day and age is loacted here:
http://www.progressivedyn.com/service_discontinued/discontinued_prod_basic_operation.html

The owners manuals are located at:
http://www.progressivedyn.com/service_discontinued/discontinued_prod_owners_manuals.html
As you can see there have been many models over the years.

Service manuals are located at:
http://www.progressivedyn.com/service_discontinued/discontinued_prod_service_manuals.html

Parts that PD still has available are loacated:
http://www.progressivedyn.com/service_parts.html

The only way the converter could be draining your battery is if it was malfuctioning.
The more likely problem is that you have a ghost circuit connected to your battery at all times.  Isolation method will partially depend on what type of setup you have.  If you have either type 1 or 2 from above, then you have a ghost circuit connected between the battery and the isolation relay in the converter.  If you have type 3, then it could be a circuit connected either before or after the fuse panel.
You will need to use one of the isolation procedures that one of our older members (Dave Dennision) provided.  Disconnect from shore power.  For very small current drains, you can get a taillamp bulb and socket.  For larger drains, use a headlamp.  You disconnect the positive battery cable from the coach batteries and place the test lamp in series with the battery.  The lamp should light up if there is a ghost current drain.  If the drain is to small (i.e. milliamps) to light the lamp, you will have to use the ampmeter portion of a multimeter.   Now that you can see indication of a ghost drain, you start pulling the house DC fuses looking to find witch circuit is causing the drain.  You simply have to divide an concur to isolate the problem to the circuit creating the problem.  It could be a refrigerator circuit (newer reefers) that monitors voltage, the clock in a radio, etc.  You simply have to systematically isolate all possible sources for the drain.

Dave

[wizardbill]

 Mine is not by Progressive Dynamics.  It is by Conversion Systems, Inc.

[DaveVA78Chieftain]

The owners manual for your 78 Georgia Boy Cruise Air is loacted here:
http://www.coachmenrv.com/owners/OwnersManuals/13998490.pdf

You will see wiring diagrams in it around page 15.  Indicates you have style 3 Converter.
It also says you have Traid TU-440-2 model Converter.  Drawins for that model are loacted here:
http://www.bryantrv.com/docs2/docs/tuseries.pdf

[wizardbill]

OK.  I went through the procedure to find what is creating the draw.

The left side fuses are always on, the right side are with ignition.

Disconnected battery, Ohmeter from positive cable to battery:  12.42V

Tested left side fuses:

1:  12.11V  Left side of fuse  12.11V Right side of fuse  Label:  Running Lamps
2:  12.11V  Left side of fuse  12.11V Right side of fuse  Label:  Batt ACC
3:  12.11V  Left side of fuse  12.11V Right side of fuse  Label:  Interior Lamps
4:    0.00V  Left side of fuse  12.11V Right side of fuse  Label:  Exterior Lamps
5:  12.42V  Left side of fuse  12.42V Right side of fuse  Label:  Inst Lamps

Before testing the right side, I retested the battery to the cable:  12.42V
Right side:

6:   12.11V  Left side of fuse  12.11V Right side of fuse  Label:  Radio
7:   12.11V  Left side of fuse  12.11V Right side of fuse  Label:  Ign Acc
8:   12.11V  Left side of fuse  12.06-12.08V (varied, unsteady)  Right side of fuse  Label:  Heater
9:   12.06V  Left side of fuse  12.11V Right side of fuse  Label:  Horn B/Up
10: 12.42V  Left side of fuse  12.42V Right side of fuse  Label:  T/Sig - GA  Br Warn

[wizardbill]

So, if I understand these test results, it would appear that I have some kind of drain to the battery at the exterior lamps?  Also, why is the voltage on the instrument panel the same as the battery?  These results are surely something someone who knows more understands.  Any help?

[wizardbill]

Is it possible that the turn signal being on could cause the power drop in the battery?  I noticed today when I started Shelby that the turn signal was left on.  I doubt that it could be the culprit, since the signals do not work when the motor is off, but it was something I noticed.

[ibdilbert01]

In short, your always going to measure a bit higher voltage at the battery terminals, as the further away from the battery and more connections you go through you'll show a voltage drop.   When you get a chance to go through the "The 12volt Side of Life" link I provided above they will go into a bit more detail including loss per wire size on part 2.

Also remember, if you take a charger off the battery and then measure the voltage of the battery, your wasting your time, as the battery has to relax a bit before giving you its true charge.  Thats called a "surface charge" mentioned on page 1.

If you think your voltage drop is not due to just the battery relaxing over night, you might want to check to see if your brake lights stick, as I recall LJ/TJ having that issue.

[DaveVA78Chieftain]

Bill,
Once you get a multimeter that can measure small amperage levels, you can then perform the parasitic test in that youtube video I showed you.  That will tell you if there is a drain or if it is just the battery settling after being charged.

Dave

[jkilbert]

bill, 
i didn't see if you specified between chassis or coach batteries. i ask this because on my coach these are separate systems and the conveter doesn't charge the chassis side when plugged in.  i do have a switch and relay that i can use to connect these for starting etc or to charge with the engine running but the ignition must be on for the relay to work. i would also load test the batteries to make sure the are in good condition since a weak battery will discharge quickly from sitting and also check all of your connections. a bad ground will also cause a battery to discharge. then check for anything that would be putting a draw on the battery.