Which side of battery disconnect to add accessories

This question is actually related to another vehicle of mine but it can apply to the 4Runner (especially those with added accessories that are connected to the battery).
I am looking into a negative terminal quick disconnect for a vehicle I don't drive often. Something like the following:

$13 Ampper Top Post Knife Blade Master Switch, 12V / 24V Battery Disconnect Switch Isolator Power Cut Off for Marine Car Boat RV ATV (Negative, Vertical)

https://www.amazon.com/dp/B07JZ9NDH2/?th=1
or

$13 Top Post Battery Master Disconnect Switch

https://www.amazon.com/Post-Battery-Master-Disconnect-Switch/dp/B001N729FS
I have an accessory that is connected to the positive and negative terminals of the battery (eyelet connector screwed to the terminals). Once I install the disconnect, should the negative lead for the accessory remain on the battery side of the disconnect or on the ground cable side of the disconnect, or will the accessory continue to draw power regardless because the positive site remains connected?
My thought process is as follows:
1. If the negative remains on the battery terminal, it will continue to draw power because accessories work if connected to a stand alone battery.
2. If the negative remains connected to the ground cable, it will continue to draw power because accessories work if power is provided and they are grounded directly to the chassis.
Excuse my lack of electrical/automotive-battery knowledge. I'm sure this is a simple answer for some. Thanks in advance.

 

If you think about it, an electrical circuit needs to be connected to both positive and negative. It needs to be a complete circuit. Just being connected to one battery terminal will not allow the device to draw current from the battery.
Havin said that, if the device is connected to the positive terminal directly, but to the chassis metal, or body metal, for it's "ground", it'll still be ABLE to function. The chassis and body metal are normally connected to the battery negative. Thus, the device is connected to the battery negative if it's grounded to the body or chassis.

A note: Using the term "ground" for a vehicle is inaccurate. Because of the tires, the vehicle is NOT grounded. At best, if you don't want to use negative, the word return is also accurate. Now to really blow your mind: Electrons, which flow through the wires to activate the various devices, actually flow from negative to positive.

As to drawing power, the add-on will draw power if it's connected to both battery terminals, AND is turned on. Most everything has an on-off switch on it. It will only draw current out of the battery if the switch is on.

Question 1: Yes, your device will draw power from the battery IF both...BOTH... battery terminals, not just one, are connected to your device, AND it's power switch is on. Just being connected to one terminal won't work. Try it with your stand alone battery.

Question 2: Exactly the route the circuit follows from positive to negative doesn't matter. Positive terminal, device, chassis, negative cable, negative terminal... Complete circuit, current CAN flow, if the device's main power switch is on.
Positive terminal, device, negative terminal...again, current can flow.
Positive terminal, device, switch, negative terminal, current can flow, if the switch is closed.

Do you understand now the basics? Electricity needs a complete path FOR current to flow though, before current WILL flow through it. However, just HAVING a complete path for current to flow doesn't mean it WILL. The device, whatever it is, must be activated. It's power switch turned on, whatever. A radio, an alarm system, a light bar, you name it. Notice they all have their own power switches?

Does this answer your question? No, you don't necessarily need to pull the negative battery terminal to stop something from drawing current. Just turn the device OFF, no current draw.
If the device has no power switch of any sort, rare, but possible, yes, just removing one of the two battery terminals will prevent current flow. Just be sure there's no path for current to flow.

Pat☺

 

Fantastic answer Pat! Thank you for clearly explaining that. It definitely makes sense. I was neglecting the last part of the circuit (chassis to negative battery terminal) in my thought process.
To clarify, on my other vehicle, the accessory is powered when the vehicle turns on (hardwired radar device that came with the vehicle) so I assume it will not draw power when the vehicle is off. The positive and negative leads are directly connected to the battery positive and negative terminals, but there must be a relay or switch in line that ties into a fuel injector fuse or similar.
I store the vehicle for the winter and typically disconnect both terminals of the battery for storage (no accessible outlets for a battery maintainer). The quick disconnect is my solution to simplify storage but I wanted to make sure I was not missing anything and clearly my brain failed me. But this explanation makes sense and I'll keep the negative connection (from the accessory) on the negative cable side of the quick disconnect and it should work fine.
Appreciate your help!