I read the information from another thread here about how to wire a 12v motion sensor but the replies confuse me a bit, can someone else please clarify this for me? This is what I'm understanding from the replies here and from amazon reviews: from the sensor we get 3 wires, connect the blue and brown wires directly to the battery to supply power to the sensor, So my confusion is the load wire. It can either be connected to the positive side of the lights or the negative side. I can tell by using common sense they are all saying connect the Load from the sensor to the positive side of the lights but user RB said and I qoute " when the unit detects movement the LOAD terminal is switched to ground" , shouldn't he have said the Load terminal is switched to power (positive)? preface I'm not an engineer, I'm just learning how to setup landscaping lights for my mom's house. the qouted thread is below:

Hi.

The three wires are connected like this;

+ (+12v)
- (12v ground)
load (connect the light between here and +12v)

So in use, when the unit detects movement the LOAD terminal is switched to ground. So the load (the light bulb) goes between +12v and the LOAD terminal.

Your 12v light should be no more than 40W for best reliability.

He also said no more than 40 watts, but my lights are 6 watt, 20 watt, and 30 watt LED floodlights. LED lights are a resistive load are they not? So it should be OK for me to use the 80 watt max load listed here? (as an example, I will go back to the product page to see the real specs of my lights).

FURTHER questions I have: I plan on separating my lights into 3 groups, front of house, left and right side of house. Each side will have it's own combination of lights to light up various things. so basically let's say on the right side of the house (if you were to look directly at the house from the street) I could have a six light string of 6 watt LED floodlights. I place a long 2 conductor wire down the right side of the house and each light's positve wire is connected to this wire on the positive side, all light's negative wires get connected to the negative wire on this 2 conductor. So the motion sensor is just a switch to connect this light string to the positive end of the battery, and the negative end of the light string connects directly to the battery negative, I think?

The actual question is that I need 2 motion sensors: one on each end of the right side of the house, that way the entire string will light up if either sensor triggers. I think I get it, the motion sensor is nothing more than a relay that requires it's own connection to the battery to provide the power to activate the relay so the Load wire is the only thing I need to worry about. I just need to wire a sensor to each end of the light string's positive wire side and add an extra 2 conductor wire to provide power to that sensor from the battery right?

Some one also said how to add a switch to bypass the sensor to light up the whole string, I never could figure that out so this forum is really helpful. just here to make sure I understand things right, hope I didn't sound too confusing.

also one last question if I were to accidentally reverse the polarity does it fry the sensor? the links to my parts

6 watts lights plus the 20 and 30 watt ones, I will repaint and silicone the whole light to waterproof it and even spray 2k urethan paint on the circuit board inside just in case
https://smile.amazon.com/dp/B08QF29G3L?ref=ppx_yo2ov_dt_b_product_details&th=1

sensors:
https://smile.amazon.com/dp/B09LQV5RWH?ref=ppx_yo2ov_dt_b_product_details&th=1

I just thought of this but I will use this wireless remote to use as a sensor bypass:
https://smile.amazon.com/dp/B09B6MRMNL?ref=ppx_yo2ov_dt_b_product_details&th=1

I have heard the best thing to do is use a relay and have all sensors activate this to activate the light strings, I will use this only if I have to: https://smile.amazon.com/dp/B079BGGVYX?ref=ppx_yo2ov_dt_b_product_details&th=1

 

Also because I do everything backwards, I still haven't figure out what power supply to use. I'm leaning towards a 12v car battery, if not enough power than 2 car batteries for 24v. They will be charged using my spare 100 watt ridged glass solar panel and my spare morningstar sunsaver 12v solar charger which has low voltage disconnect. my other ideas were Lithium titanate which was ruled out due to the low AH capacity and high price

next is my experience with using used $20 HP or Dell server power supplies, they provide huge 60-80 amps at about 12.3volts DC, I know I can adjust the potentiometer to boost the voltage somewhere around or under 14 volts. I know how to series connect them for 24 and 48 volts and I know about floating the grounds so I don't get electrocuted. I'm still not sure yet, maybe I can stick it in a box and waterproof it because I'm not sure if it'll survive outside.

next idea: use LED driver power supplies which are waterproof (or so they say) but they have low power output. next is I have knowledge about LIFEPO4 and I already have 8 280AH cells (actually 250AH because the seller sold me used damaged cells) the problem is LIFEPO4 cannot be used in the cold near freezing so I need to make an insulated blanket and put a heater under them which I don't really know how to do. lastly using Eneloops and making a battery pack, but it's tedious and the cost seems high so the car battery thing seems to be where I'm leaning to, or LIFEPO4. car batterys I get 40 AH if the battery is 80AH , not sure if it's enough for what I'm doing unless I combine 2 car batteries.

 

I just figured out why everyone says to use a relay, it cuts down the length of the wire run due to the second sensor being run to the other side of the house, plus I no longer worry about the sensor's max power rating. I hope that's it

 

LED lights are a resistive load are they not?

No, they are NOT.

He also said no more than 40 watts, but my lights are 6 watt, 20 watt, and 30 watt LED floodlights.

That’s 56 watts. And if you’re using a string of six 6 Watt lights, that’s 86 Watts. More th as n 80 Watts and way more than the recommended 40 Watts. You never want to run at the maximum. The maximum is when the device fails.

So it should be OK for me to use the 80 watt max load listed here?

No.

I could have a six light string of 6 watt LED floodlights.

This would require 36 Watts.

 

No, they are NOT.

I disagree with that. LEDs are a non linear resistive load.

 

Also because I do everything backwards, I still haven't figure out what power supply to use. I'm leaning towards a 12v car battery, if not enough power than 2 car batteries for 24v.

You can't use two batteries in series for 24 volts that would exceed the rating of the sensor and the LED lights. As far as power for the LEDs use a 12 volt AC transformer designed for landscape lighting.

 

You can't use two batteries in series for 24 volts that would exceed the rating of the sensor and the LED lights. As far as power for the LEDs use a 12 volt AC transformer designed for landscape lighting.

actually I've been using a 18v lithium ion battery pack from an old drill, I metered it at over 20v and I tested 1 light with the motion sensor because I bought a 10watt (actually it pulls 6 watts) and it has a preinstalled sensor, it looks the same as the 3 pack of sensors I bought. that 20v battery has successfully powered on all my 10watt lights and the 20 watt one too. You might have seen the description of 1 of the items but chinese products, if you cross reference them from multiple sellers you'll see additional specs, so basically both the sensors and lights run at somewhere from about 9 volts to probably 24 volts or more. I know the lights will run on the same voltage on AC power, I don't know about the sensor but they might.

in any case I'm trying to run it off the solar panel and a battery because my mom is cheap/ worries about the electricity bill. I know it makes no sense, but it's pointless arguing with her.

So is the way I described how to wire the string of lights with 2 or more motion sensors correct? I think I can figure out how to use the relay, I just want to make sure my thinking is right, chinese products are known to be confusing, even electricians post reviews that say they're confused about things like the wire coloring, they say its wrong but actually it is correct for IEC which is europe/ UK

 

Sounds correct with the sensors and relay. I think it best if you isolate the relay coil from each sensor using diodes.

 

I disagree with that. LEDs are a non linear resistive load.

And I disagree with that but I’m not going to argue the point.

 

Sounds correct with the sensors and relay. I think it best if you isolate the relay coil from each sensor using diodes.
View attachment 286630

Thanks for that, what size and what type of diodes do I use? Also why did you turn it around and make the relay switch the negative side because the motion sensors were going to switch the positive side connecting all the lights to positive, unless I misunderstood that? I am not a electronic hobbyist , I do not know the basics, just making sure you know that. I have no fundamental understanding of electronics other than I can do basic soldering , like really basic stuff. and I can swap out AC light switches and outlets only by watching youtube videos.

 

And I disagree with that but I’m not going to argue the point.

I said LED lights are resistive because that's what the google results say, what he's saying is on point with what other people are writing. That's the perspective I'm on. it says LED are mostly resistive except for the part which isn't so it's mostly a resistive load.

 

Thanks for that, what size and what type of diodes do I use? Also why did you turn it around and make the relay switch the negative side because the motion....

1N4001 diode will suffice.
The schematic shows how the relay coil is connected not the relay contacts.
Google how a relay works.

 

1N4001 diode will suffice.
The schematic shows how the relay coil is connected not the relay contacts.
Google how a relay works.

will do thank you

 

You may also check this thread: https://forum.allaboutcircuits.com/threads/how-to-wire-a-12v-pir-motion-sensor.94821/