When on inverter am I using the batteries?

[Tinstar]

When I'm parked, plugged into shore power and I'm plugged into the inverter outlet in the refrigerator compartment, is the electricity coming from the shoreline or from my batteries?

I guess I'm asking if I am draining my batteries with the refrigerator (or other appliance) by being plugged into an inverted outlet and replenishing them at the same time with the shore power or am I bypassing the batteries since I'm plugged into shore power?

Additionally, if it's coming from the batteries, should I switch to the shore power outlet to keep from running on them?

I hope my question makes sense.

[msturtz]

Tinstar wrote:

msturtz wrote:

dougrainer wrote:
Msturtz.From just one of the various RV Transfer switch makers instructions. Doug

BEFORE TESTING:
Ensure air conditioning units and other high current users are switched off.
It is harmful for the transfer switch to switch over power sources while under load.
Shut down all power sources to the RV
Label power sources clearly that testing is in progress.
If accessible, remove the lid of the ATS to visually check function

Are you saying that you have documentation from the ATS manufacturer(s) that state that all power must be removed when switching power sources?

I think you just read it: "from one of the various RV Transfer switch makers"

Testing is not equal to normal operation.

[Mile_High]

When did the TESTING section apply to normal use?

[Tinstar]

msturtz wrote:

dougrainer wrote:
Msturtz.From just one of the various RV Transfer switch makers instructions. Doug

BEFORE TESTING:
Ensure air conditioning units and other high current users are switched off.
It is harmful for the transfer switch to switch over power sources while under load.
Shut down all power sources to the RV
Label power sources clearly that testing is in progress.
If accessible, remove the lid of the ATS to visually check function

Are you saying that you have documentation from the ATS manufacturer(s) that state that all power must be removed when switching power sources?

I think you just read it: "from one of the various RV Transfer switch makers"

[tropical36]

dougrainer wrote:

devildog1971 wrote:
If your inverter is off will your batteries still charge? I am new to the class A R V they are a lot different from the truck campers I have had until now. sorry to cut into the thread but maybe the op might need to know also.

You need to post the Brand and Model of Inverter and year/brand/model of RV. In simple terms, IF you have an Inverter/Charger, and you turn the Inverter OFF, only the Invert side is off, the charger remains ON. Since this is a motorhome forum, most motorhomes have an Inverter/Charger, not an Inverter ONLY. Doug

Not an inverter only, but a lot of converter only's. Then there's all the ones with additional and separate standalone inverters and have installed these myself.

[pianotuna]

I prefer to unplug so as to NOT switch under load. In some ways I wish my Magnum inverter did NOT have a transfer switch built in. I do take some comfort that the switch is rated for 60 amps and I'm in a 30 amp RV.

Yet, I've seen Cameco female outlets "burn" when used on a 15 amp shore power supply, even after being treated with deoxit. I won't even buy them any more. The male Cameco seem to work just fine.

[pianotuna]

I wonder if the new solid state relays have contacts to burn?

[tropical36]

Tinstar wrote:
When I'm parked, plugged into shore power and I'm plugged into the inverter outlet in the refrigerator compartment, is the electricity coming from the shoreline or from my batteries?

I guess I'm asking if I am draining my batteries with the refrigerator (or other appliance) by being plugged into an inverted outlet and replenishing them at the same time with the shore power or am I bypassing the batteries since I'm plugged into shore power?

Additionally, if it's coming from the batteries, should I switch to the shore power outlet to keep from running on them?

I hope my question makes sense.

Can't say for your coach and don't even know what you have, but with ours, there's a pass through feature with pretty much the whole house outlets. The exception being the block heater, which is shore only and one of the two outlets behind the fridge, which is shore only. Either way, shouldn't be a biggie and just like with our old coach and whereas I installed a separate inverter and ran some outlets. Consequently by doing this and if they were in use, when hooked up, the batteries would be replenished continually, by the converter/charger.

[wolfe10]

See my post above.

Can you switch under load, YES. Does it pit/burn the contacts, YES. Amount of damage depends on size of contacts, material they are made of and amount of current and(IMPORTANT)how frequently you do it.

There is always a point where the contacts are not yet in full physical contact, but the air gap has diminished to a point that electricity arcs across the gap.

[rgatijnet1]

When plugged in to shore power, on my coach, the 12 volt items are still connected to the batteries so any lights that I use, vent fans, etc. will still be drawing power from the batteries, even while I am plugged in to shore power. Naturally the inverter/charger will keep my batteries charged while plugged in.

[msturtz]

dougrainer wrote:
Msturtz. You have "experience"? I have 38 years as an RV technician and still working. I guess I have experience also:B From just one of the various RV Transfer switch makers instructions. Doug

BEFORE TESTING:
Ensure air conditioning units and other high current users are switched off. It is
harmful for the transfer switch to switch over power sources while under load.
Shut down all power sources to the RV
Label power sources clearly that testing is in progress.
If accessible, remove the lid of the ATS to visually check function

Are you saying that you have documentation from the ATS manufacturer(s) that state that all power must be removed when switching power sources? If so, I would absolutely love to see it. I have seen some crazy things in the RV world that would arguably not comply with NEC or any other rational code. That said I work for a heavy truck manufacturer in the Research department. I have specified, removed, & installed large UPS systems as well as I have installed standby generator system with 100 AMP split phase computer controlled transfer switch. I have also installed split phase 240 VAC EVSE equipment that similar to ATS equipment the transfer is ALWAYS done "under load". Your point about arcing across the contacts is possible especially with very old and slow switch gear but with modern switch gear the components should last the life of the coach. Having said all this it is usually a good idea to turn off large loads when switching especially when switching from shore to generator. The reason is many generators are under powered and will sag voltage and spike current when a sudden load is transferred over. It is better for the generator to have a smaller load transferred. In my coach the generator is biased by the switch gear so if the generator is on it is powering the coach. I also have an EMS system with a 2 minute delay timer. The net effect of this is the incoming power is delayed by two minutes before cutover. Also my coach as an AGS (Automatic Generator Start) system. By definition, I would not be able to run around switching off power before the system starts the generator. It happens automatically without any intervention from me. If it was damaging or unsafe to "hot switch" between inverter and generator power I'm quite sure that the coach manufacturer would not have installed such a system.

[dougrainer]

Msturtz. You have "experience"? I have 38 years as an RV technician and still working. I guess I have experience also:B From just one of the various RV Transfer switch makers instructions. Doug

BEFORE TESTING:
Ensure air conditioning units and other high current users are switched off. It is
harmful for the transfer switch to switch over power sources while under load.
Shut down all power sources to the RV
Label power sources clearly that testing is in progress.
If accessible, remove the lid of the ATS to visually check function

[wolfe10]

msturtz wrote:

dougrainer wrote:
What Mr Wizard states is TRUE. But not for the reason he stated. You ALWAYS disconnect Shore Power before starting the Genset AND turn off the Interior MAIN Breaker/s. You NEVER Transfer with a LOAD. This prevents arc'ing of the Transfer relay points, which causes wear and premature failure. Read posts from people that state they have multiple failures of Transfer boxes. Caused by transferring under load. You also Turne Loads OFF when turning the Genset OFF. Some Transfer boxes close a relay when connecting either Shore or Genset. Some, the Shore relay stays closed. Unless you know for sure which style you have always have NO LOAD when engaging various Power supplies. Doug

I'm sorry to have to disagree with you. Proper transfer switches are designed to switch "under load". I have experience with RV type transfer switches but also automatic emergency generator systems. These systems routinely transfer "under load" by definition. The same is true for UPS systems which I have specified in my job. While it is true that the relays can wear out over time due to arcing that should be minimal as these devices are specifically designed to be operated in this manner. In fact, properly designed and implemented transfer switches should be completely transparent to any connected system i.e. the dropout should be less than a fraction of a phase cycle. The capacitors in most equipment should bridge that short of a mid cycle dropout. More advanced transfer equipment common in UPSes can actually use phase drift to wait until both sources are in phase prior to switching over. RV switch gear usually isn't that advanced unfortunately. Bottom line is with a properly wired and designed system (RVIA and NEC codes) in no case should anything bad happen if you have all three sources of power available at the same time. It CAN happen with a mis-wired coach or with defective equipment however the underlying problem MUST be corrected rather than masking it by turning off all sources of power prior to switching over. All this said if a person wants to cut all power and then start up the new source go ahead but it will only be a marginal at best savings on the transfer switch(s).

Here we are getting into "best practices" vs "what I got away with".

Both statements are correct. YOU have to decide which philosophy you want to follow.

[msturtz]

dougrainer wrote:
What Mr Wizard states is TRUE. But not for the reason he stated. You ALWAYS disconnect Shore Power before starting the Genset AND turn off the Interior MAIN Breaker/s. You NEVER Transfer with a LOAD. This prevents arc'ing of the Transfer relay points, which causes wear and premature failure. Read posts from people that state they have multiple failures of Transfer boxes. Caused by transferring under load. You also Turne Loads OFF when turning the Genset OFF. Some Transfer boxes close a relay when connecting either Shore or Genset. Some, the Shore relay stays closed. Unless you know for sure which style you have always have NO LOAD when engaging various Power supplies. Doug

I'm sorry to have to disagree with you. Proper transfer switches are designed to switch "under load". I have experience with RV type transfer switches but also automatic emergency generator systems. These systems routinely transfer "under load" by definition. The same is true for UPS systems which I have specified in my job. While it is true that the relays can wear out over time due to arcing that should be minimal as these devices are specifically designed to be operated in this manner. In fact, properly designed and implemented transfer switches should be completely transparent to any connected system i.e. the dropout should be less than a fraction of a phase cycle. The capacitors in most equipment should bridge that short of a mid cycle dropout. More advanced transfer equipment common in UPSes can actually use phase drift to wait until both sources are in phase prior to switching over. RV switch gear usually isn't that advanced unfortunately. Bottom line is with a properly wired and designed system (RVIA and NEC codes) in no case should anything bad happen if you have all three sources of power available at the same time. It CAN happen with a mis-wired coach or with defective equipment however the underlying problem MUST be corrected rather than masking it by turning off all sources of power prior to switching over. All this said if a person wants to cut all power and then start up the new source go ahead but it will only be a marginal at best savings on the transfer switch(s).

[dougrainer]

devildog1971 wrote:
If your inverter is off will your batteries still charge? I am new to the class A R V they are a lot different from the truck campers I have had until now. sorry to cut into the thread but maybe the op might need to know also.

You need to post the Brand and Model of Inverter and year/brand/model of RV. In simple terms, IF you have an Inverter/Charger, and you turn the Inverter OFF, only the Invert side is off, the charger remains ON. Since this is a motorhome forum, most motorhomes have an Inverter/Charger, not an Inverter ONLY. Doug