I want to put LED lights inside and LED Flood lights on outside of cargo trailer.
I want to have two sources of power 1st source will be permanent 120v AC power, and 2nd source will be two DeWalt 20v batteries wired in Parallel.
can I have both sources feeding the Rocker style switches? I assume I would need some diodes but unsure where to connect them.
from my attached diagram is there anything I'm missing and do all the voltages and wattages check out?
Would you also suggest getting larger Amp Hour rated Dewalt Batteries?
I'll attach the links of the items I'm trying to use for this project. thanks
DeWalt Battery Adapter
Digital Low Voltage Protector
DC Voltage Regulator Buck Converter
12V 10A DC universal regulated switching power supply
3 Gang rocker switch panel
Interior LED lights (1 set)
Exterior Flood Lights (set of 2)
DeWalt 20v 5AH (2 Pack)

 

You are missing a charger product made to charge the 18V to 20V Lithium-Ion batteries. The adapter simply physically makes connections and the protector ad even says it is not a charger.

 

You are missing a charger product made to charge the 18V to 20V Lithium-Ion batteries. The adapter simply physically makes connections and the protector ad even says it is not a charger.

Your right, I do plan to remove them from the adapter when they need to be charged and I have a few chargers already with the Dewalt power tools I already own.

 

If you're using a dc /dc converter, remember it will take more power from the batteries than it gives out, so if you want 11A output then it's going to draw about 6A from the batteries.

 

It would be simpler to use a 12V battery. Ideally a LiFePO4, or the cheapest house-brand lead-acid, or whatever you have lying around. Add a solar panel on the roof and a $10 charge controller (which includes an LCD voltage display and a couple of USB ports for charging).
https://www.amazon.com/ExpertPower-Rechargeable-2500-7000-lifetime-Applications/dp/B07X523S96
LFP is more expensive intially, but the longer life and greater usable capacity may make them cheaper in the long run.

 

With Li-Ion batteries you run a risk of fire. Not that there's anything wrong with your circuit, just that Li-Ion's do have that danger. Charge them incorrectly or discharge them incorrectly and you can hurt them or worse. LiFePo is more stable. Not likely to experience a catastrophic fire.

You said you plan on plugging the DeWalt batteries into your circuit. When they need recharging you're going to swap them out with charged batteries and put the depleted batteries on the charger. Since you're planning on using the DeWalt charger for the batteries you should be safe. Just make sure of this: When running on AC you don't want any power back feeding into the batteries. That could create an unsafe condition. You'll need a diode to block reverse current from reaching the batteries. It's not likely you're going to see any back feeding through your buck converter, but still, a diode just makes it that much safer. You (or should I say "I" - "me") don't know how the buck will respond to seeing an inputting voltage on its output stage. As far as an LVDO circuit (Low Voltage Drop Out) the batteries should have internal protection for that.