1989 Itasca SunFlyer main battery issue (long)

I am borrowing a 1989 Itasca SunFlyer from my in-laws for the summer, and have run into an odd issue.  When I turn the key, the RV acts like it has a dead main battery.  I have a switch on the dash for checking voltage; the aux batteries read 12-14V depending, and the main battery just BARELY moves the needle.  This battery has been hooked to a trickle charger, and plugged into my wall for a month now with no issues, and the charger reads "CHARGED".  I removed the battery cables thinking that maybe the trickle charger was 'reading' the aux batteries not the main battery.  No change. Both the trickle charger, and a different charger I put on the battery show it as charged.  A multimeter on the terminals with no cables connected reads 12.8V.

I cleaned both + and - cable ends, attached them to the battery, removed the ground cable from the frame, cleaned that up with a die grinder and reattached.  No change.

I pulled down the front of the breaker panel under the hood to expose the two large solenoids, etc.  Everywhere I check voltage, I get the same battery voltage of 12.8 or so.  I removed and cleaned up every ground location I could find, and read resistance to the negative battery cable that's grounded on the frame......all under 1ohm, so I have a good ground.

Some things that seem odd.

1) There is a switch on the dash for apparently tying the aux batteries to the main battery for a boosting application? When I move that switch and look at the voltage on the main, and aux, batteries, I see no change in either voltage, but hear a solenoid or relay clicking somewhere (its hard to tell which one, as I'm working alone).  I also removed the cables from the terminals on the solenoids, moved / scrubbed them against each other to improve contact, and reattached.  No change.

2) Although the main battery is charged, and I can measure voltage all over the place, the starter won't engage, the headlights don't light up when I pull out the switch, and if I turn on the hazards, I can hear the faintest clicking of the flasher relay, but its not enough to make the directionals illuminate.

3) About 1 in 5 times I check the voltage on the main battery with the dash switch, it goes right to 12V, and when I turn the key, the check engine and choke lights illuminate on the dash like everything is good, but as soon as I turn the key to start it, all lights go out, battery drops to zilch, and I'm dead in the water again.  I've seen this before with dirty battery terminals, but I've already cleaned them up!!!

This entire past winter and spring, the RV was parked, plugged into house power at the rear, with the same trickle charger on the main battery under the hood.  When I arrived to take possession of it, it fired up perfectly and has been issue-free since.

I'm really scratching my head on this, its like there is a large fuse, or solenoid, or relay that brings main battery power out, and that its not functioning......almost like a bad positive battery cable.


Edit by John:  changed message icon to Topic Solved

It sounds like you have done about every thing I can think of.
Can you check the voltage right on the engine battery terminal while you are trying to crank it or use the lights? That way you can see if the battery has a high internal resistance.
If the voltage doesn't drop on the terminal then you know that a connection that looks good isn't.

but as soon as I turn the key to start it, all lights go out, battery drops to zilch,

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This is typical of a defective (shorted) starter relay or starter motor. What chassis is it Ford, GM etc?

Its a GM chassis.  454.

I don't see how a shorted starter motor or solenoid would cause me to have no power anywhere else though, like headlights, radio, directionals, etc.  If it were THAT shorted, I'd have a straight path to ground for the main battery and it would literally fry, correct???

When the relay kicks in it breaks contact to your other items to give full power to starter.(dash lights go out while cranking) If relay is bad it makes sense that you might see that.

I would be looking at a bad chassis ground for the main (starting) battery, or a corroded connection on the main battery hot wire. Since you have good voltage at the solenoids, any hot wire corrosion would be beyond that point. I think a ground problem is a better bet, though.

captsteve....

I'm aware that the lights go out on the dash to give full power to the starter, but when I say they go out, they go out, and never come back.  They don't illuminate every time I turn the key.  Maybe every 10th time, and I'm NOWHERE NEAR being able to even begin to turn over the starter motor.


On the front  'crossmember' there is a 3/8" stud sticking up to the right of the main battery that's used as a ground. I cleaned around it with a die grinder / roloc wheel, cleaned up the end of the neg. battery cable, and polished up the underside of the nut that clamps it all togther.  It SHOULD be a good ground, but I'll attempt something different later on.

Both cables appear 100% free of corrosion, but again I'll check.  Its an intermittent problem, as well a quality-of-connection problem.  Intermittent as every 10th time I check voltage with the dash gauge, I have voltage.  Quality of connection, being as soon as I attempt to draw current, the circuit opens up and I'm back to little-to-no voltage.

I was also going to remove the house batteries and start looking for where voltage stops.  Any voltage present will HAVE to have come from the main battery.

** scratching head**

If the relay is bad and sticking (most of the time) it could do exactly as you say. OTOH so could a bad cable.

captsteve said:

If the relay is bad and sticking (most of the time) it could do exactly as you say. OTOH so could a bad cable.

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I don't think so.  Looking at the ohms law of it...........if that stuck relay was pulling down my battery from 12-13V, to almost 0 volts, that's an absolutely dead short, similar to if you dropped a piece of metal across the terminals of the battery.  MASSIVE current, sparks, blown pieces, melted wiring, fire, etc.

A slight short may pull a battery down from 12-13V, to maybe 10-11V, and that's still enough current to melt wiring.

I my reply above I mentioned a shorted starter but a defective starter with a jammed armature will do exactly that as well.  I have had to change several in my time. One test you can make is to disconnect the starter wire at the starter, isolate it, then try again and see if the symptoms repeat or not.

If it does turn out to be that, change the starter relay too as you have done no favours to its contacts with those heavy current draws. If you don't change it now, you will be within the year!!!

Alfa38User said:

I my reply above I mentioned a shorted starter but a defective starter with a jammed armature will do exactly that as well.  I have had to change several in my time. One test you can make is to disconnect the starter wire at the starter, isolate it, then try again and see if the symptoms repeat or not.

If it does turn out to be that, change the starter relay too as you have done no favours to its contacts with those heavy current draws. If you don't change it now, you will be within the year!!!

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Pulling the + starter cable is a good idea.  I'll do that and see where it gets me. 

Need to load test the battery at your local parts house, you can have 12 volts but no amps.

I ground down a new grounding point on the frame for the negative battery terminal, attached, and checked.  No change.  I tightened up the nuts on both solenoids under the hood; no change.  I attempted to remove the + cable from the starter to isolate it, but gave up momentarily to look for a flashlight.  While searching, I unplugged the RV from shore power, and plugged it back in.........I could hear a click when this happens.  For kicks, I plugged it in and out about 10x, hearing the relay click each time, and all of a sudden, I have power.

Headlights work, engine cranks strong, battery reads 12V all the time, etc.  I'm not sure what I did, if anything at all.

I'm wondering if you have a flaky solenoid.  Let us know if this reappears. 

Its hard to tell where the clicking occurs when I plug into shore power.  Is it one of the large solenoids under the hood that triggers?  I'm working by myself and can only hear a click from the front of the RV when I plug in.