Switching from Genny to Shore Power under load----bad?

[wopachop]

Got to the trailer and started the genny its been over a month.
Then plugged into shore power with an amp reader because i was curious if it would switch over.
Started the A/C and let it run for awhile.
Then turned off the genny with both A/Cs cranked full blast.
Only hooked up to 15amp.
Ran and killed the front bedroom manual hand dial.
Then turned the main room thermostat to off.

What damage can that cause to the electrical switch and the air conditioner?

[MrWizard]

wopachop wrote:
Got to the trailer and started the genny its been over a month.
Then plugged into shore power with an amp reader because i was curious if it would switch over.
Started the A/C and let it run for awhile.
Then turned off the genny with both A/Cs cranked full blast.
Only hooked up to 15amp.
Ran and killed the front bedroom manual hand dial.
Then turned the main room thermostat to off.

What damage can that cause to the electrical switch and the air conditioner?

amp reader do you mean a KILL-A-Watt meter or something similar for 15amp circuits ?

in most RV's generator takes priority
plugging into shore power did Nothing until you turned off the generator

depending on how fast you ran and turned them off
you might have still been on genny connection
the genny voltage has to drop below a set point before the TS will drop out and switch to shore power
I think somewhere below 90v
as the genny winds down the voltage drops, the TS disconnects and goes to shore mode when the voltage is to low to hold the relay closed

this winding down, causes a feedback from A/C compressors fan motors
called 'back EMF' this can damage the generator
this why you don't shut down with heavy loads running,
even when shore power is NOT in play

turn off A/C before stopping the generator
make sure A/C is in the off position before starting the generator
or plugging in the shore cord, this prevents genny damage or arcing the shore cord blades

[AllegroD]

Also of note is 2 AC on 15 amp circuit. Not only is this iffy, because the circuit may have other items on it, say a freezer in the garage, which could cause an overload on the circuit, causing it to open. If 2 AC are running on 15 amp, you also stand a very great chance of low voltage. Voltage lower than 105 will cause AC to increase power and therefore heat damage which you do not see until the AC dies prematurely. Using an undersized extension cord or hockey puck adapter will over heat those items and cause melt down and fire hazards.

[MrWizard]

sorry for the confusion, its the "our converter automatically switches" thing

that is the same for every RV

the converter is connected to the house breaker box

the converter is on, no matter which 120v source you have, shore or generator, the converter doesn't switch between anything
the ATS chooses your 120v power source, the converter like the rest of the RV, uses what ever is available

[doxiemom11]

MrWizard wrote:
Sam
When you move it, manual transfer, you are unplugging it
You disconnect either by manual switch or by physically moving some cord plug

Doxiemom
I think you mean you have an auto start for the genny
It's not the converter, it does sense battery voltage and start the genny when the battery is low, so the converter can charge them

No, we do not have an auto start. We have to start the generator ourselves if we want it running. Not sure what part of my post you are questioning. We have a rocker switch on our dash to start the generator from inside. Our converter automatically switches off from the shore power to the generator if we start it running. We do not have to disconnect the shore power.

[wopachop]

Thanks for all the help everyone. I know that i need to invest time into reading the manuals. I enjoy reading manuals.

This morning i noticed something weird. The way the converter and solar were interacting. Its almost like when the solar was in charge mode, the converter would not send out power. But then when the solar relaxed, the converter decided to be the power source.

Here is what happened. Might not make sense.

1. Plugged into shore power, solar is hooked up, and i had the battery disconnect set to ON. (forgot to turn it off)
2. Woke up and noticed the solar display was at 14.4v, and giving 2amps.
3. Thats different than normal. Realized i forgot to turn off a light in the storage compartment.
4. Flip the disconnect to OFF, and the solar amp goes to zero.
5. Turn back on and solar takes over the 2amp draw.

Now im confused myself!! Trying to remember.

6. Once again turn the battery disconnect off and wait a bit. The solar display starts to drop to 13.6v. I think that part i understand as the solar will drop to 13.5v float charge when it considers the batteries to be 100%. Which the display showed them as.

7. Whats weird is i try the same test. Turn on my rear cargo lights that draw 4amp. I turn the battery disconnect to ON, but this time the converter takes over. Solar display stays at zero and my clamp meter shows the converter wire giving power to the 12v system.

---------------------
Whats that all about? Its like while the solar was in 14.4v charging mode, the converter decided to NOT take over. But when the solar was at 13.5v, the converter supplied the power.

I know this might seem silly to some. Im just messing around trying to see what the trailer does. Normally im on shore power with the battery disconnect turned off and the solar maintains the batteries.

[turbojimmy]

wopachop wrote:
I can barely run off a 15 amp breaker either. Temporarily hooked the 14 gauge wire to a spare 20amp breaker. The garage outlet im using is about 30 feet from the panel. From there its a 50' 10 gauge electrical cord. Need to install a 30 or 50 amp setup at some point if im going to be doing the shore power thing during the summer temps.

I have a similar issue. I have a 20A circuit fed by 12 gauge wire, but it's easily 50 feet from my panel. Then I have a 100-foot, 12-gauge extension cord from that outside outlet to the rig. I use it mainly to keep the batteries charged. A/C will run but it's not happy about it. Voltage drops to under 100 volts. When I do need to run the A/C I move the rig closer to the house and plug the RV's power cord right into the 20A outlet.

[wopachop]

I got rushed because i looked outside and saw my friend was waiting in the car. Turned on the genny and heard the main A/C change sound. Instantly realized i did exactly what i didnt want to do. Ran to the front bedroom and turned that A/C off which is a hand dial switch. So within 3 seconds of turning off the genny i had also killed 1 of the a/c units.

I can barely run off a 15 amp breaker either. Temporarily hooked the 14 gauge wire to a spare 20amp breaker. The garage outlet im using is about 30 feet from the panel. From there its a 50' 10 gauge electrical cord. Need to install a 30 or 50 amp setup at some point if im going to be doing the shore power thing during the summer temps.

[turbojimmy]

Like everyone else said, switching power sources under a load will shorten the life of the transfer switch.

As far as 2 A/Cs running off of a 15A circuit (even briefly), that's impressive. I can barely run one of mine. But my rig is wired so that the 2nd A/C doesn't get any juice from the shore power.

[MrWizard]

Sam
When you move it, manual transfer, you are unplugging it
You disconnect either by manual switch or by physically moving some cord plug

Doxiemom
I think you mean you have an auto start for the genny
It's not the converter, it does sense battery voltage and start the genny when the battery is low, so the converter can charge them

[Sam_Spade]

MrWizard wrote:

never start the genny when plugged into shore power

never plug in to shore power while the genny is running

While this is good general advice, it really doesn't apply if you have a "manual" transfer like many C's do....and some A's too.

Moving my cord to a different plug is my "transfer".
(Since my transfer switch fried and I re-wired without it.)

[Sam_Spade]

wopachop wrote:

What damage can that cause to the electrical switch and the air conditioner?

You won't know until something fails. Seriously.

Switching under a heavy load is BAD.....no matter what kind of system you have. It should be avoided whenever possible.

Systems designed for auto-startup or auto-switching should have that happen VERY infrequently and even those are not intended to be switched "hot" all of the time.

[Chris_Bryant]

Transfer switches always will choose genset if it's running and producing power.

[doxiemom11]

We have an automatic converter with an interior switch to start the generator. We do shut off any major power draw items prior to starting or stopping the generator, but do not unplug from shore power. It depends on what equipment you have on whether you need to unplug from shore power or not. Do not change power source when under power load though.

[MrWizard]

converter

has nothing to do with this situation, neither would an inverter-combo

which uses the batteries

you went from genny 110v to shore 110v

never start the genny when plugged into shore power

never plug in to shore power while the genny is running

[CA_Traveler]

Plugged in to shore power with the battery is charged and then starting the gen is a non issue.

You're asking the right questions and trust many don't.