Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 13, 2025 ...

power

December 02, 2015, 02:25:50 pm

I don't know if I am in the proper forum for a technical question, but here goes. My '94 U300 suddenly lost power to most of the coach while plugged in to shore power. I switched to the inverter and it brought power back. However, both shore power and APU power bring the power to the switch box under the bed which powers the coach temporarily, and then within 10 seconds the power goes out. We tested the input power to the switch box and find only 102 volts there.  Is it possible that something upstream is affecting the power to the switch and subsequently the circuit breakers and therefore with not enough actual 110 voltage, dropping power completely? You can repeat this scenario, watch the power engage the switch box, and then 10 seconds later the power goes away. Any ideas?

Quote Selected

Re: power

Reply #1 – December 02, 2015, 02:50:22 pm

Does the same thing happen on generator? If so, that pretty much rules out shore power itself, shore power cord and connections/wiring from side of coach to ATS.

Do you have a power monitor/surge guard?  If so, installed before or after the ATS?

Quote Selected

Re: power

Reply #2 – December 02, 2015, 05:09:25 pm

Are you plugged into 30 or 50 amps? Like Brett says, if the gen set runs it's in the coach/ pedestal. We've had serious problems with bogus shore power.

Quote Selected

Re: power

Reply #3 – December 02, 2015, 09:29:53 pm

It malfunctions on either shore power or apu and we have hooked to two different shore powers. Does the power run first to the converter and then to the switch box under the bed? We only show 102 volts at the input of that unit and perhaps the converter is siphoning off some volts [never heard of such a thing]. The scenario is this...connect power via the shore or apu..the switch box engages some seconds later..the coach powers up..then goes dark 10 seconds later.

Quote Selected

Re: power

Reply #4 – December 02, 2015, 10:00:51 pm

NO.  The two sources of 120 VAC (shore power and generator) "meet" at the ATS (Automatic Transfer Switch.

From there your 4 wires (two hots, a neutral and ground) go to the main 120 VAC breaker box.  You don't say what coach you have, so can't tell you exactly where it is, but on most Foretravels under the leading edge of the bed. 

From there, the breakers supply everything including the converter.

IF, repeat IF you are safe working around electricity, turn off generator, disable auto gen set start, turn off inverter and unplug from shore power.

Open the ATS and breaker box and check carefully that the connections are clean and tight and that there are no signs of overheating.

Quote Selected

Re: power

Reply #5 – December 02, 2015, 10:08:57 pm

Thanks..this is a '94 U300..I already checked inside the transfer box and thing are great there, although that is where we find only 102 volts at input wires..

Quote Selected

Re: power

Reply #6 – December 02, 2015, 10:21:41 pm

Very difficult to believe that both shore power and generator would simultaneously go from good power down to 102 VAC. Assume you have verified that your voltmeter is accurate.

I would start with the shore power side of things:
What is voltage at the CG outlet? If good there, check again at the "IN" side of the ATS.  18 VAC is a LOT to loose!  Said another way, that much resistance can generate a LOT of heat.  Enough to cause a fire. 

Please find the problem/have a qualified electrician find the problem.

Quote Selected

Re: power

Reply #7 – December 02, 2015, 10:43:04 pm

If measuring 102V at the input term of the ATS...... What is the amperage at the time?

If little or none, then most likely a loose connection on the line side somewhere.

If high amperage then possibly a large load or short on the load side of the ATS.

Hard to diagnose electrical problems on the computer or over the phone. I am asked these type questions at work all the time.

Quote Selected

Re: power

Reply #8 – December 02, 2015, 10:55:46 pm

I will get somebody to come look at it. Could very well be that my voltmeter is faulty..[it's new but the leads keep coming out of their socket so yeah...I don't trust it] All the correct outlets work when disconnected from shore or apu and just running off of the inverter..typical electrical...like a needle in haystack sometimes.  What about ground..does that ring a bell at all?

Quote Selected

Re: power

Reply #9 – December 03, 2015, 12:42:47 am

Speaking of "ground," are DC ground (usually the negative battery post) and AC ground (sometimes called earth ground) the same thing? Even a fallen away electrical engineer can get confused.    Or do our moterhomes actually have two different "grounds"?
 
Trent

Quote Selected

Re: power

Reply #10 – December 03, 2015, 05:38:39 am

The battery negative posts should be tied to the chassis frame (at some point) as is the equipment grounding conductor "green" or "bare copper" conductor of the 240/120 V AC system. (not to be confused with the "white" or neutral conductor)
They should be at the same potential.

Positive ground systems are uncommon (at least here in the States) never actually worked on one myself.

Quote Selected

Re: power

Reply #11 – December 03, 2015, 07:57:07 am

Mine did something lie that on the generator last summer, I would start generator hear transfer switch close. Turn on a/c's and shortly front a/c would quit.Did this 2 or 3 times. Checked voltage at outlets and kitchen side would be low. Shut everything down restarted generator and checked voltage at transfer switch. everything good. reset all breakers including main, main  on generator too. restarted everything worked fine. Has not had a issue since, on shore or generator. I dunno. I am thinking I had a bad contact either at the transfer switch or a main breaker but until it fails again , am at a standstill.It's been working fine.

Quote Selected

Re: power

Reply #12 – December 03, 2015, 11:23:55 pm

So...it seems that the #5 50 amp circuit first runs down to the heart interface and then does not return power to the breaker box on the foot of the bed that runs all the outlets. I turned the main breaker off...tested the incoming line to that secondary breaker box..it showed 110 volts for 10 seconds...then went dark. So..the heart must be the culprit. Does anyone have any experience with that inverter/converter..can contacts be cleaned, etc...or is it a remove and replace?

Quote Selected

Re: power

Reply #13 – December 04, 2015, 07:52:26 am

Is your inverter/converter a black Freedom 20 or 25? If so they can be repaired to some extent. Some people upgrade to a pure sine wave rather than repairing the Freedom series as they are a modified sine wave. There is a fellow on one of the solar forums that in the past has done repairs on the Freedom series and has all the repair info. I will hunt down his info if yours is a Freedom and post it here.

Pamela & Mike

Quote Selected

Re: power

Reply #14 – December 04, 2015, 04:38:57 pm

This is a freedom 25

Quote Selected

Re: power

Reply #15 – December 04, 2015, 05:02:53 pm

David,

Here is the fellow I was talking about
Photovoltaic Systems
James Kerbel
7910 Hwy 54 
(715) 824-2069
Wisconsin Rapids, WI

Don't know if he is still in business but he had all the manuals and anything else that you needed to do a repair on the older units. It just took me a little time to run him down.

Pamela & Mike

Quote Selected

Re: power

Reply #16 – December 05, 2015, 12:37:35 am

Thank you so much..

Quote Selected

Re: power

Reply #17 – December 05, 2015, 08:33:53 pm

So...got a new volt meter and all power checked out perfectly fine to the input side of the Transfer switch and subsequently...after checking everything over, the wife [now I feel lucky and stupid at the same time] noticed that the transfer switch reset button on the the inverter was popped..we reset that and..Viola..everything good! So...since I seem to remember checking that reset button days ago and it was not popped..I am sorta at a loss as to what happened here. Perhaps it needed to be manually popped somehow and reset in order to "reboot" the inverter? Anyway..all seems well for now and perhaps a heavy load on the whole circuit popped that button and it didn't come all the way out so that it could be properly reset? Hopefully this is the last of the problem, but we will keep those outlets engaged to a minimum and know where to look if we repeat?

Quote Selected

Re: power

Reply #18 – December 05, 2015, 08:50:29 pm

Glad you figured it out. 

We were at HWH a couple years ago. All was done and we were gertting ready to leave and no 12v anywhere.  The HWH folks and I spent a half hour checking everything and then my DW asked if we had checked the master 12v switch near the front door. It was off, probably snagged on a pants cuff or something. Felt bad and glad at the same time. 

After five years now when we are trying to diagnose a problem we always try to start with the most obvious, the simplest posible thing we can think of. Don't over complicate things until you need to.

Quote Selected