Need Help Finding Electrical Problem

pianotuna wrote:

I'd recommend replacing the converter if it is bad.

With a converter that old that has separate charge and convert outputs (as suggested by it having a bypass relay that switches when it turns on and off), it would be a significant upgrade to replace it with a modern multi-stage converter regardless: it would provide cleaner DC output, charge the battery much more quickly, and probably generate less heat and hum doing so. The DC distribution panel would need a very simple modification to join the "filtered" and "unfiltered" busses together.

You have refreshed some old old memories of my first 1989 Class C. Brand new and the house battery took forever to charge. I now remember it isolated the battery and only charged it at 3 amps. What a pain that was. I added a ten amp charger but that was still wimpy.

It sure got cold in Colorado when the heater ran out of battery power.

Check the output from the converter at the fridge.
Check the output from the converter at the lights.
Check the output from the converter at the house battery bank.

I'd recommend replacing the converter if it is bad.

Ray,

I may be the one here with the most experience with vintage aka old hard ware. This is not to say that what was written above had any errors, because I sure didn't see any. I am real glad that you gave us a good set of references and you have a meter handy.

Please start by recognizing that with a coach that old, virtually anything could be bad, been mis-wired or broken. Take nothing for granted.

The relay you hear click is very possibly part of the problem. (Caution - Working with old memories here.) That unit was designed to both supply 12V for house service and recharge the house bank as separate items. (the relay). It did this because the house bank can use a higher voltage to charge than the light bulbs like.

I do not believe that this converter has the capability to link the house to the main engine charging system. That link seems to be functioning properly. That is why you have 12V with the ignition on. This is actually mis-connected if I read you right. It should only link the main engine to the house battery when the engine is actually running.

The fact that nothing works on shore power would indicate that the isolation relay and that part of the converter have failed. At this age, that is certainly no surprise.

I would like you to do a couple tests first off.
Check the battery at the posts.
Do you see something between 12.0 and 12.6 with things at rest?
If less than 12.0, the battery is dead. At least try to charge it before continuing.

Inspect the converter/charger and determine which terminals go to the battery and which to the house distribution. By you account (thank you) the pair that go to the battery should show battery voltage without shore power and something more with it.
Yes/No?
Yes means the charger part is working.
No means you are not charging that bank on shore power.

I suspect that what is not happening is that the converter/charger is not making the required connection between the house bank and the house distribution panel. So, when there is no shore power, the two pair if terminals should show matching power levels. If this is not the case, then the problem is inside the converter/charger. If you have a very electric friendly friend or relative, it can probably be repaired. That could be low cost, but I would advise against it. The reason is down the page.

As YC mentioned, there is probably a contactor (big relay) that connects the house to the main engine electrics to recharge that bank from the engine.
Next, Monitor the house battery voltage.
Does it increase with the main engine running?
Yes/No?
If yes, you have something to leave alone. (I suspect this is the case.)
If no, then there is something amiss in that circuit or contactor. It may just be a mis-connection as that the house distribution should be connected to the house bank and and the engine when the engine is running and there is no shore power.

Hopefully, we have identified the problems. If it is the converter itself. I do not recommend repairing it only because the newer "Smart Converters" with a three or four stage capability are so much better than what you have even if it was working. To this end, I suggest you contact Best Converter and talk to someone there. What you have is probably the correct capacity for your coach so there is no need to buy more then 30amp. Both Progressive Dynamics and Iota are good and there may be others now.

If I lost you along the way, please try to tell me where and I will do my best to clear that up.

Matt

That vintage may have a switch that is momentary one direction for auxiliary start, center position is off and dual in other position. When driving the switch would be in dual to charge the coach battery. Camping you would be in off.
Some older converter had two output sections. One was clean power and one is dirty. Look in 12 volt DC distribution panel for two fuses from converter.
Manual

With the ignition on there is likely a solenoid that combines both banks of batteries. So your refer and house battery is seeing the engine battery voltage plus the charging voltage if connected to shoreline.

IF your house battery is bad then removing the path from the engine battery may see the house battery voltage going to near zero if it is really dead.

Check your house battery voltage without the key on or shoreline connected.

If you find it to be ok, plug back into shoreline and take the measurement again, then turn the ignition switch on and take that measurement. Write them down as you go. It is easy to get derailed taking a lot of measurements.

This could be a simple automatic resetting circuit breaker not functioning. With those measurements we should be able to sort it out quickly.