Brian Martin
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How would the camera get damaged if you used a POE injector ? Isn't that the same as power coming from a switch or the NVR ?
Dahua 2MP 25x Starlight IR PTZ Network Camera (SD49225T-HN)
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Zeddy
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TBH my understanding of how POE worked is the camera should have negotiated the higher power limit and the switch should have refused.
So I'm thinking of buying this cam to replace my old (barely 2 years- but had some short circuit). Does this POE switch suffice? ZyXEL GS1900-24HP
This should have POE+, so I should be ok, right?
Is this the right way or better alternatives for that amount?
This should have POE+, so I should be ok, right?
Is this the right way or better alternatives for that amount?
Brian Martin
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If you have a POE switch hooked to the camera and an external power pack to power the camera , the POE switch should not be supplying power. Also the Camera should be negotiating what source of power it is drawing from. If the power pack is connected the camera should not be calling for power over POE.
Injectors, do not pull power from a POE switch. The POE switch should see the injector is not calling for power and shut the power off to the Cat cable going to the injector. The injector see's power being called by the camera and then supplies it to the camera.
Plugging a 5 watt camera into a 15 watt injector does not result in 10 watts of power being lost somewhere; the camera will simply draw as much electrical power as it needs. The power circuit in the camera should be regulating the power it needs.
Injectors, do not pull power from a POE switch. The POE switch should see the injector is not calling for power and shut the power off to the Cat cable going to the injector. The injector see's power being called by the camera and then supplies it to the camera.
Plugging a 5 watt camera into a 15 watt injector does not result in 10 watts of power being lost somewhere; the camera will simply draw as much electrical power as it needs. The power circuit in the camera should be regulating the power it needs.
Brian Martin
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Semper Gumby
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Amazing that is the same wooden test bed setup I built!
Brian Martin
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LOL . What do they say great minds think alike.
Only makes sense to make a test stand with a PTZ. I am not going to go up and down a ladder several times to test a camera!
I need to put a SD card in it tonight and then run a few tests to make certain that is working also.
hmjgriffon
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ima mod my test rig, the bucket and rocks thing works, but my back still hurts from moving it around.
Semper Gumby
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I thought he was saying it could be damaged by using PoE instead of PoE+. Maybe.
I had my Reolink RLC-423 hooked up for a week to a PoE switch and it took me that long to notice that when I try to use PTZ at night (when the IR lights are on), it kept rebooting. Turned out I totally missed the part about PoE+ in the specs and just plugged it into the same switch as the others... it booted so I figured I was good.
The combined power draw of the IR lights *and* the PTZ motor was enough to send it over 15.4W resulting in a (mostly) harmless reboot as the switch just shut off the power in the event of an overload condition.
The PoE+ injector I used was this little fella: Amazon.com: TRENDnet Gigabit Power over Ethernet Plus (PoE+) Injector, TPE-115GI: Computers & Accessories (TRENDnet Gigabit Power over Ethernet Plus (PoE+) Injector, TPE-115GI). Currently $29.99 USD, Amazon Prime. I better pick up another one now that I think about it, for my hopefully soon to arrive Dahua PTZ.
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nayr
IPCT Contributor
@hmjgriffon had an ultra bullet w/heater that required PoE+ but he gave it PoE, I think he burned the heater up underpowering it and its now preventing the camera from booting.. @EMPIRETECANDY is warrantying the camera w/no hasstle, but now he has to go w/out his prized camera for a few more weeks while it gets fixed.
Cameras dont negotiate the amount of power they want from the switch, they just negotiate power and then take what they need.. PoE and PoE+ are the same negotiating and backwards/forward compatible, a PoE+ device wont know its talking to a PoE supply until it needs power it dont have.
Cameras dont negotiate the amount of power they want from the switch, they just negotiate power and then take what they need.. PoE and PoE+ are the same negotiating and backwards/forward compatible, a PoE+ device wont know its talking to a PoE supply until it needs power it dont have.
Ouch. I wonder what PoE (switch or injector) he had. They *should* cut off the power if it were to exceed the limits (consider the case of a short in the device once power draw was negotiated...the switch would shut it down to protect itself).
If, on the other hand, it merely limited the power to 15.4W instead of shutting off, I could see how that would lead to potential undervoltage which, in the case of a heater element, would indeed cause big problems. Bummer.
I could be wrong in thinking a PoE port should cut off power in a situation like that, I haven't really read the spec or read up on that, I'm just thinking that's how it *should* work, like a self-resetting breaker. Meh... now I'm curious and will have to check it out. At least in the case of solid-state components, not getting enough juice is likely to just cause it to not work, but it wouldn't really fry anything, which is also why I'm not surprised it was the heater that went belly up in the same situation.
nayr
IPCT Contributor
I believe he used a dumb passive injector, I suspect alot like what @Brian Martin posted above
Also the wattage the PoE outputs is not the wattage the PoE Inputs, its only guaranteed to provide 12.95W on the other end of the line due to voltage drop..
Also the wattage the PoE outputs is not the wattage the PoE Inputs, its only guaranteed to provide 12.95W on the other end of the line due to voltage drop..
hmjgriffon
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I can vouch for that, very sad, hope I can get it back soon, I'm tempted to buy another just to not be without until then lol
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Semper Gumby
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This site is the greatest! Got my SD49225T yesterday (only 2 days from Hong Kong, thanks Andy) and got it running yesterday in the web browser. I thought it would take a couple of days to get it running with Blue Iris, but followed the suggestions here on the thread. Updated Blue Iris to Ver 4.5.1.4, and set it to “Dahua Other” and boom it is up and running. Next step is to install it outside.
Brian Martin
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Are you saying a POE switch of any sort regulates the power / current to the device and the device does not regulate the power ?
nayr
IPCT Contributor
thats not how power supplies work.. devices consume what it needs.. It dont ask the PSU for 30W of power, it just takes 30W of power and the PSU better be up to the task.
You can use a 10A PSU on a device that needs 1A, but you cant use a 1A PSU for a device that needs 10A..
You can use a 10A PSU on a device that needs 1A, but you cant use a 1A PSU for a device that needs 10A..
looney2ns
IPCT Contributor
If you value your electronics, don't assume what power supplies they need. Read the specs.
hmjgriffon
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Yes, I used one of those little WS whatever injectors, camera ran fine for like a week, I played with everything even cranking the IR up all the way and never any issues so I'm still suspect on the heater thing but it died from something.
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hmjgriffon
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Also it was running round the clock while it was alive
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