Inverter By-Pass

[truk4u]

Jon,

Don't know yet about the CC, although the roof A/C's are not tied to the inverters, but my 97 Marathon was dead in the water if the inverters went south. You have to rig up a bypass such as your discussing to get power. I experimented prior to shutting everything down when replacing the house batteries, and the Coach was a dead duck without the inverters.

This is really a good point Jon is bringing up, shut off the inverters while plugged in and see what you get. In my vintage Marathon, there was no power. I mean no plugs, no A/C, no fridge, nothing. While everything was off for my battery work, I ran and extension cord to the refrigerator plug to keep that going.

Nick was going to help me with the bypass switch when he got close to Atlanta, but I sold Big Red before we could pull it off.

[Jon Wehrenberg]

For those questioning the "why" of this, it is possible (unless the coach has a bypass built in) for a failure of the relay which passes shore or generator power through the inverter to fail. When that occurs no power will pass through the inverter even though it is available.

Don't assume yours will automatically transfer power or by-pass until you have tested to confirm your suspicions. The time to know is before you have a problem, and the solution is less than $100 in parts. Why some coaches were or are built without a by-pass is a question for the converters, but I do know for sure that my coach is not alone with this design.

[bill&jody]

time to drag out all those schematics, jon.

[JIM CHALOUPKA]

time to drag out all those schematics, jon.

That would be nice, but I seem to recall. that Liberty does not furnish electrical schematics. What do you say Jon, is that so?

[Jon Wehrenberg]

The schematics are provided by Liberty, and I assume others, but not at the level relevant to this issue. My Liberty owner's manual is very detailed as to the wiring.

This is not a Liberty issue. This is strictly related to how your particular coach was set up when it was built or modified. Shore or Generator power will either by-pass a failed inverter, or it will not. If it does not I will write an article that shows how to by-pass one in the event of a failure for a few hours of work and less than $100.

In the event I am not understood, this is not related to the automatic switching that occurs when you go from inverter power to shore power to generator power. This relates solely to having power available to the coach in the form of shore or generator power, but not being able to get it to circuits normally fed through the inverter because of an inverter malfunction. Some coaches are equipped to by-pass the inverter so it doesn't matter if the inverter works or not. Others however will not.

[Joe Cannarozzi]

Jon IMO this thread is a perfect example of the beauty of POG.

Let me rephrase my question from my previous post.

Why would they design that system so all circuits that are powered by the inverters could not be powered by gen. or shore when available, without needing the inverters?

If our switch fails in a manner that takes those circuits offline I simply remove the inverter from the loop. Its behind the wall behind the freezer, 10 min. max.

If you remember ours was not working when we bought the bus. All circuits continued to function and we left it in cause the battery charger end of it was still good.

Once I did remove it for repair I could plug the recepticals leading to and from it into each other to complete those circuits. On a side note that switch was one of the things that failed. A contact was burnt keeping the inverter function down but could have just as easily burnt the other side restricting shore/gen.

Seems like what your trying to achieve is exactly the set up we have and it was designed 10 years prior to yours.

Unnecessarily overcomplicated, a relatively common occurrence on many features on these campers

Jon If I were in the market for another bus and it's style was EXACTLY what we wanted but had inverters set up like yours, I'd pass, I would not be willing to risk that inconvenience unnecessarily.

It will be reassuring and informative to hear from new coach owners, and who their converters are, who do not have to deal with this.

Jon here is Daves# at Gusdorf electronics 505-983-4095. He knows inverters as well as you know norgrin valves. I'm sure he is aware of your set-up and can be of some assistance.

[Jon Wehrenberg]

Joe,

I cannot defend the design except to say that was the way things were done, and yours and mine being at least 10 years apart show that the way they were installed was not a one time thing, but was common practice. I know for certain that several converters built a lot of coaches that way, and I also know of at least one Prevost owner that lost the contents of his refrigerator because he could not get power to it after his inverter failed. I also know of a coach built in 1995 for a former PP president that was specifically equipped with an outlet for the refrigerator powered by shore or generator power to be used as a backup in the event of an inverter failure. This problem is not new or unheard of.

In our coaches we have many failure modes that are capable of messing up a trip. The fact that with 10 minutes worth of rewiring gets you going says more about how your inverters are placed than the whole concept of being able to by-pass a failed device with a simple switch.

I am addressing potential failure modes in my coach one at a time. I dealt with a plumbing issue previously. I have made access to engine fuel priming much easier. I am going to deal with an inverter failure via a by-pass switch, and I am adding a second water pump solely to be used as a standby. Each time I find something whose failure will force me to repair it immediately, or which will disable us making life less than pleasant I am going to incorporate some means of dealing with it.

In the end I will still have some items whose failure will require a repair, but I am adding parts to my inventory of spares to minimize the grief. I already have a replacement control for the Webasto, a backup Watchdog generator control, miscellaneous circuit breakers, relays, air hoses, lights, etc. And those things that are not practical to replace, or to have back-up, or to repair I am going to replace based on time in service or miles such as I am contemplating for my engine air compressor or my big alternator.

If we never left the immediate area we live in I would never consider doing what I am doing. But that is not the case, so I will do the next best thing and that is try to never have a failure while on the road that will curtail a trip. At least that is the plan.