Can I run off AC with no house batteries?

[rhythmtone]

Hi,
I'm in the process of rebuilding my battery drawer, which is badly rusted, before purchasing new house batteries.

But family is coming for Thanksgiving, so my question is, can I run off 30 AMP AC without the house batteries installed? Or might this cause damage?

I know for a fact that when using the generator the batteries must be there to "be part of the system" and absorb loads when the Cool Cat or microwave click on.

But is it safe to use just the 30 AMP AC connection the entire time with just bare wires where the house batteries are? I'm not totally sure about battery disconnects and inverters and converters and such.

2006 Roadtrek Versatile w/ Victron solar / battery MGMT system.

Thank you!

[booster]

Originally Posted by rhythmtone

Hi,
I'm in the process of rebuilding my battery drawer, which is badly rusted, before purchasing new house batteries.

But family is coming for Thanksgiving, so my question is, can I run off 30 AMP AC without the house batteries installed? Or might this cause damage?

I know for a fact that when using the generator the batteries must be there to "be part of the system" and absorb loads when the Cool Cat or microwave click on.

But is it safe to use just the 30 AMP AC connection the entire time with just bare wires where the house batteries are? I'm not totally sure about battery disconnects and inverters and converters and such.

2006 Roadtrek Versatile w/ Victron solar / battery MGMT system.

Thank you!

As long as you are sure any charging sources are unpowered, you would be OK to do that.


That means you need to shut off the AC input to the charger.


It means you can't start the van engine unless you disconnect the charging cable to the coach.


This means if you have any solar that the panels have to be disconnected from the controller.


A bit of work, but doable, depending on ease of access to those items.


It would be easier to just use some taped up jumper cables to a battery set on the ground along side the van and connected to the cables in the battery area, again taped up.

[rhythmtone]

Thank you for the quick reply!

So the charger can't have AC input with no load? That would actually damage it? Not quite sure how easy that would be to disconnect.

Normally I CAN start the main engine on AC, at least I think I could, and I have ... But with no house batteries that changes things?

Solar panels are totally external and live on the ground when used, so no issues there.

I guess the ground battery idea is the best, I do still have the old ones, and they are almost shot but they still provide a connection and a load etc.

Could you briefly comment on the charger and main engine issues I mentioned above?

Thanks again, as always, you're very helpful!
Dave

Originally Posted by booster

As long as you are sure any charging sources are unpowered, you would be OK to do that.


That means you need to shut off the AC input to the charger.


It means you can't start the van engine unless you disconnect the charging cable to the coach.


This means if you have any solar that the panels have to be disconnected from the controller.


A bit of work, but doable, depending on ease of access to those items.


It would be easier to just use some taped up jumper cables to a battery set on the ground along side the van and connected to the cables in the battery area, again taped up.

[booster]

Originally Posted by rhythmtone

Thank you for the quick reply!

So the charger can't have AC input with no load? That would actually damage it? Not quite sure how easy that would be to disconnect.

Normally I CAN start the main engine on AC, at least I think I could, and I have ... But with no house batteries that changes things?

Solar panels are totally external and live on the ground when used, so no issues there.

I guess the ground battery idea is the best, I do still have the old ones, and they are almost shot but they still provide a connection and a load etc.

Could you briefly comment on the charger and main engine issues I mentioned above?

Thanks again, as always, you're very helpful!
Dave

While the charger might damage itself if it doesn't have a battery in the circuit, it is probably just as much a risk to any and all other 12v items connected to it on the output side. With no battery reference chargers can go high on voltage and damage things unless they are the style that check for a battery before connecting. If we knew your charger make and model we may be able to find out if it would or not connect. IMO even it wouldn't connect it is a tough call to say it is absolutely OK.


The engine may be OK to run IF you an isolater and not a separator and have good connections to the coach. If the charger is totally disconnected it is likely you could get away with it as the starting battery will control the voltage. You would get into trouble only if the charger was active and powered by seeing the starting battery but then a breaker tripped in the line to the starting battery. Then the charger would go high on voltage, most likely.


If you run the engine you also have to remember that the disconnected cables will be hot and with lots of power available.


The key is the charger being totally disconnected but is often hard to do on the AC side.


That is why the battery on the ground and jumper cables looks like the best solution. The van would function just like it would with the batteries in place and on shore power.

[hbn7hj]

You can turn the converter off by turning it’s circuit breaker off.
AC has nothing to do with engine start.

You could run the refrigerator on AC by removing the DC fuse and connecting the refrigerator DC power input to a 12 volt automotive battery.

Just some opinions. Booster’s comments are correct. He doesn’t miss much, if any, and knows more than I do.

[rhythmtone]

Thanks for the replies, I think I will go with hooking up the old almost dead coach batteries on the ground.

Just as an aside though, to clarify 100% - it is okay to run the engine while connected to AC under normal circumstances with healthy batteries connected and such, correct?

It's not often but sometimes I do this to warm up the engine and cabin with main engine heat, prior to disconnecting AC, just kind of a departure procedure - is that okay? I know to never have AC and generator but I thought AC and main engine were okay, under normal circumstances.

Thanks again,
Dave

[booster]

Originally Posted by rhythmtone

Thanks for the replies, I think I will go with hooking up the old almost dead coach batteries on the ground.

Just as an aside though, to clarify 100% - it is okay to run the engine while connected to AC under normal circumstances with healthy batteries connected and such, correct?

It's not often but sometimes I do this to warm up the engine and cabin with main engine heat, prior to disconnecting AC, just kind of a departure procedure - is that okay? I know to never have AC and generator but I thought AC and main engine were okay, under normal circumstances.

Thanks again,
Dave

Yes you can run the engine while on AC power without issue when in normal use.

[hbn7hj]

Correct, It is OK to run AC with engine running. Not usually done but OK.

[rhythmtone]

Great thank you for the replies, as always very helpful, and I learned something.

Happy camping,
Dave

[mkguitar]

unless you REALLY understand how your electrical system works


I would suggest you not try to cowboy anything


put a battery in place temporarily at least and electrically you should be safe and not risk damage.