Hey all,
I am working on wiring up a boutique trailer with lighting for the Mrs's mobile boutique and the scenario I came up with was to operate off battery power when mobile or at shows, but be able to plug-in to AC power when at home.
I've provided a conceptual drawing of the setup I believe will work and am looking for validation on setup, components, and most of all safety. Here is how I plan to operate it:

1. The two power supplies will never be operational for the lights at the same time. Will always be one OR the other.
2. When parked at home, it will be plugged into an inlet plug with a built-in splitter and will operate from the LED driver for the lights. On the battery side, there is an isolator switch that will be set to Off. During this, however the inlet plug will be attached to an on-board charger that recharges/maintains the battery.
3. When at shows where no AC power is available, it will have the isolator switch set to 'On' and there will be nothing plugged into the external side of the inlet plug.
4. Both the LED driver and the battery would be permanently attached, just not always have inlet power available.

Based on my drawing, does this seem like a good setup? Any worries about power back-feeding to the other side unintentionally? Is there any worry of not having isolators or anything like that on the negative lines?
Please don't roast me too badly, I'm a newb

TIA

 

Welcome to AAC.

SUMMARY: some form of ATS seems preferable but if you are going manual then simplify it to a single, break-before-make, properly rated DPDT switch to completely isolate the two sources and eliminate the possibility of “misconfiguring” (e.g.: forgetting the bypass switch)

Your wiring diagram is a bit hard to follow, but I am going to suggest you consider something like this module instead. It’s cheap (less than $5), and very simple. I takes the mains-powered driver in one input and the battery in the other. When the mains-powered supply isn’t hot, the battery is on, and when it is there, the battery is disconnected in its favor.

They are only rated at 150W, so you may need more than one. (You don’t specify what the load is). If you do try this route, it is important to test it with your scenario. The only concern is the cutover time which, by design, should be short enough to avoid exposing the load to over-voltage but it is a cheap and (hopefully) cheerful Chinese module so verifying the function is important.

If you don’t go this way, I will counsel you that it is critically important that the safety or damage prevention in your system must not depend on a person remembering to do something (like operate a switch) because they will forget at least once and the results could be very costly.

You could do something that requires the switch operation for the system to work at all, such as a limit switch on the shore power input that shuts off the battery supply when the cover is opened. Or, you could arrange your own ATS (Automatic Transfer Switch), or possibly adapt one of the inexpensive ATS options that usually expect 120V in each input, I haven’t trued this.

Most simply, you could just have a large break-before-make DPDT switch that selects between the two. That is, instead of a bypass arrangement, you have to actively select the source and they are completely isolated. This means no current steering diode is required, and absolutely no change of cross connection is possible.

In any case what you want to do it not very difficult but you have to be sure you know exactly how you want it to behave and exactly what sort of ratings the components will need to be reliable.

 

Look into how home power is switched over to a generator. You have exactly the same thing. Electric codes do not allow a separate disconnect, for good reason, they require that it is switched by a single switch so that is is impossible to connect both at the same time.

You can also use a relay powered by the AC inlet. Thus makes it automatic, plug in the AC and the battery power is automatically disconnected. That is the way I would do it, because I am lazy.

 

Thank you both for the suggestion. I was unaware these battery switch modules existed. I assume this would take the place of the Diode in my drawing, but I like the fact that both the positive and negative lines go into it rather than just controlling the positive lines. Unfortunately, I'll have to look more into those, because my calculations show I'll need a 200w and 20amp to support my setup. (100% Load draw being about 180w).

The manual isolator switch is mainly there for when the low voltage cutoff gets triggered, I can kill the circuit going to it so that module does not continue to drain battery once the voltage gets too low to operate the lights. It's a small draw on the power, but still a draw nonetheless.

I think in the interim until I am ready to modify it, I may just keep it simple and only keep the battery side and forego the split. My onboard charger is a smart charger/maintainer and will charge the battery faster than I can drain it so I should be able to just plugin to AC to charge the battery while I continue to use the battery to provide power.

 

You could, as a stop gap, put Andersen Powerpole connectors on the input to the lighting circuit and on the output from the battery. Then you could put one on a mains-powered LED driver and connect it if you want to. It would be completely foolproof and if you made it easily accessible, very simple to cut over.

 

You could, as a stop gap, put Andersen Powerpole connectors on the input to the lighting circuit and on the output from the battery. Then you could put one on a mains-powered LED driver and connect it if you want to. It would be completely foolproof and if you made it easily accessible, very simple to cut over.

Oh. I also did not think of that. That would be a super easy way to achieve the split. And not over complicate the circuit as well as avoid an inevitable lapse of forgetting to throw a manual switch and power both to the lighting circuit together. Good looking out!

 

Hey all,
I am working on wiring up a boutique trailer with lighting for the Mrs's mobile boutique and the scenario I came up with was to operate off battery power when mobile or at shows, but be able to plug-in to AC power when at home.
I've provided a conceptual drawing of the setup I believe will work and am looking for validation on setup, components, and most of all safety. Here is how I plan to operate it:

1. The two power supplies will never be operational for the lights at the same time. Will always be one OR the other.
2. When parked at home, it will be plugged into an inlet plug with a built-in splitter and will operate from the LED driver for the lights. On the battery side, there is an isolator switch that will be set to Off. During this, however the inlet plug will be attached to an on-board charger that recharges/maintains the battery.
3. When at shows where no AC power is available, it will have the isolator switch set to 'On' and there will be nothing plugged into the external side of the inlet plug.
4. Both the LED driver and the battery would be permanently attached, just not always have inlet power available.

View attachment 298140

Based on my drawing, does this seem like a good setup? Any worries about power back-feeding to the other side unintentionally? Is there any worry of not having isolators or anything like that on the negative lines?
Please don't roast me too badly, I'm a newb

TIA

I have a diorama with a wall power supply Jack on the side and a battery supply underneath. Also on the side I have a SPDT switch to choose which supply to use, wouldn’t that work for you or am I not understanding what you are trying to do?