Shore Power Only Works When Engine Is On

His problem is, his COACH battery system is inop. Either his batteries are DEAD or they will not connect thru the battery disconnect system. When he fires up the chassis engine, he gets 12 volt power to the COACH from the chassis Alternator/Chassis battery. THAT allows the EMS system to power up. It takes 12 volts for the EMS to power up and close the various shed relay's. BUT, The EMS does NOT stop 120 power to the NON Shed items. But, he has not told us and he may not know, what type of COACH 12 volt charging system does he have? Does he have a INVERTER/CHARGER or does he have a regular POWER CONVERTER? Either one, it is obviously NOT working, or it would supply 12 volt power once his chassis side supplied 12 volt power to the coach when engine running and either his genset or Shore Power was supplying 120 to the RV. Doug

it really does sound like the the EMS is not getting any 12v power from the house circuits, there fore its relays are not engaging

the relays only have power when the alternator has output

he has dead or disconnected house batteries, and a converter that is NOT coming on once 120vac is engaged

he could try setting the EMS to bypass aka off while the engine is running
maybe he can keep shore power engaged so he can trouble shoot the 12v supply problem

adhooligan wrote:
My Class A Southwind has an issue recently that the generator AND shore power will only work if the chassis engine is running. Once I turn off the engine, within 30 seconds any shore power or generator will be cut off and no power is available for the coach.

I swear I answered this on another forum or, at an alternate place on this forum but, I cannot find it in all my answers to questions. Hmmmmm. Wonder where it went????

Anyway, in all my RV life, I've never heard of the ignition of the engine, having any effects on shore power or generator power, operating correctly. My keys to my coach and be in my pocket and, I can still start up the generator and it will power things up just fine. And that includes all outlets that are connected to that system which, is just about all of them.

And that goes for shore power too. My keys can be in my pocket, the engine off and, if I plug into 50A shore power, it goes right to work, powering things up and, supplying all outlets with 130VAC, plus or minus.

This is an amazing issue for sure. For any part of the shore power or, generator power operations, to be tied to the ignition of the main engine, is by far, a new one on me.

Now, I'm only referring to the allowance of 130VAC to be allowed to enter the coach and, be present at all outlets. I'm not talking about Inverter/charger doing its job of charging the batteries or anything like that. That's a totally separate problem. Most large inverter/chargers allow what's called "Pass through" operations when plugged into shore power. That is, they allow incoming VAC to PASS THROUGH the inverter/charger and, proceed right to the 130VAC breaker panel.

The Transfer switch, normally controls where the power to the outlets comes from. That is, if you're "Inverting" (using house battery power for 130VAC) and then, fire up the generator, the transfer switch automatically uses proprietary protocol and, switches to generator power and, the inverter/charger, immediately goes on "standby".

It will operate the exact same, if shore power is introduced while inverting.

But, none of that operation, as far as I know, has anything do to with the ignition of the coach. Now, unless I'm reading the OPs question(s) all wrong, something's really odd here for the ignition of the coach, to shut down shore power or, generator power operations. Hmmmmm.
Scott

I had a southwind 2005. Under the hood you have a BCC battery control center. Inside it has 3 relays
main , aux and charge relays. Try pushing you aux button on your dash with the engine not running, That button ties both battery's together. The ground for your coach battery goes to the chassis and is bolted . Mine came loose once And I had similar symptons

I had same problem on my Fleetwood Excursion. Mine was caused by one ground wire not being reconnected after changing coach batteries. I would check for that or a bad ground connection. Good Luck

It has been awhile since I have seen a diagram of the EMS but I think the relays in the EMS work off 12VDC if so it would sound like the house batteries are dead or disconnected and the EMS is getting 12V from the engine running.

MrWizard has covered all the basics above.

This is what exactly happened. Went to RV park last week. Full 50 amp hook up. I plugged in to 50 amp shore. Turned on breaker. Went to RV and nothing was on. Checked breaker if tripped, it was ok. Checked breakers in RV, they were ok. I turned on engine and the 50 amp service started up. 50 amp showed up on my Energy Management System, and everything started up, lights, refrigerator, AC. I turned off engine and within 30 seconds, everything goes dead, nothing lights up on EMS. Everything shuts off.

I believe the transfer switch relay is powered by 120 VAC. It is energized by the 120 VAC coming from the shore power or the generator output.

you have NO 12v house power
house batteries are dead or disconnected and the converter (which runs from the 120v) is not charging,
possibilities
blown charge fuse
circuit breaker for converter is tripped
converter has died, will not output any DC power
converter got unplugged in the electrical bay
in all cases there is NO 12v power to the DC coil in the transfer switch
so the switch/relay releases aka opens contacts and shuts off the 120v incoming
is this RV 50 amp or 30amp
50amp has double coils/relays
30amp has single coil/relay and should supply power from generator or shore power
one mode or the other will be default and work on a 30amp regardless of battery situation

I would like to hear a better description of the problem also.