Inexpensive solution for power source with backup

[metricus]

I know there are many ways to power your cams. I am sharing this one as it works for me and maybe someone else may use it.

My philosophy was to use wifi cams as this allowed me to have the least amount of cables and minimal holes through the brick walls.

12V 3A UPS power supply: 28.99 from Amazon
12V 7mAh Battery: 10-15$
Wires, connectors.

I am powering 3 x DS-2532 and the battery last more than 8 hours. I am yet to find out exactly how much it really lasts.

Hope it helps.

 

[whoslooking]

If you need a backup battery supply buy an Intruder Alarm power Supply something like an Elmdene 3amp.
That will do what you want and safely, what you have done is not safe and is in un-regulated and will cook the battery to a point of breakdown, and when the go bang they go bang.

 

[alastairstevenson]

I was starting to post on safety grounds too - till I discovered that this is not a home mod, but how the power supply comes when purchased from Amazon.
If all that the seller / manufacturer has done is to solder a couple of battery leads inside the case in parallel with the normal regulated output then there is quite a hazard should the output suffer a short circuit or other overload as there will be none of the usual protection needed from such a source. And you kinduv wonder how the power supply will cope with the backfeed off the battery on mains failure.
A battery like that will supply a massive current with enough energy to start a fire.

 

[whoslooking]

The power supply, is one of the cheap cctv 9 way box unit you see on eBay / amazon they are more like a PC supply and all the ones I've seen don't have a real backup connection. But they may have some that do too. Also I see no fuses for the battery just mains supply.

 

[metricus]

It's funny how people react to wires. My wife said I was building a bomb which seems to agree with whoslooking.

As you figured out there is no home mod here. The PS is doing what it's supposed to do. Battery is not overheating, it,s not even warm.

This is the exact setup like any Honeywell Vista alarm panels which are in millions out there. Same also as any UPS that you buy for your computer. They use the exact same 12 V battery except that the UPS converts the 12DC back to 120V AC (or 220 depending where you are).

Based on my measurements and tests there is nothing wrong. Also, there is a fusible link on the unit.

The PS comes in it's own retail box and does display the CE and FCC logos. IDK if it means anything.

So no I am not proposing a home mod but something that is used as it's supposed to be used.

I think the whole purpose of this forum is how to make things work for you when they are not part of mainstream retail supply.

And again, I KNOW that there are many other options out there.

Also I accept your opinion that it's bad or may fail but please give me a technical reason not a doomsday scenario.

 

[SyconsciousAu]

I am powering 3 x DS-2532 and the battery last more than 8 hours. I am yet to find out exactly how much it really lasts.

You want to avoid cycling those little 7.2Ah Batteries like that. Repeated deep discharge shortens their life to very little.

There are a few builds around the net where people have taken cheap second hand UPS units and recycled them with large batteries. Google FrankenUPS.

 

[Michelin Man]

The reason why the batteries aren't overheating is because at 13.5v it is not high enough to overcome the internal resistance to start overcharging charging. At least not at a high enough rate to cause it to overheat. It's like a uncontrolled trickle charge, I personally wouldn't do it just this way. If I had to do something like this I would use a charger that could be left on continuously and had a separate power supply to power the cameras, then have a relay switch over to the battery when mains power fails.

However at the same time, my NVR will die when the mains cuts out. So what I would rather do is have a small UPS, and install say a decent size deep cycle battery to keep everything (router, modem, NVR, phones, cameras, switches, firewall, etc) running.

SLA batteries like all other lead acid batteries do not like to be discharged past 50% which will reduce their lifespan significantly, however for backup purposes it's fine as it's not for cyclic use. If it was for cyclic use I'd be looking at some deep cycle batteries, even then, they last longer when you don't discharge them all the way down but they will tolerate this usage.

 

[alastairstevenson]

I think the whole purpose of this forum is how to make things work for you when they are not part of mainstream retail supply.

Yes, indeed, and credit to you for sharing. You've generated a fair bit of interest and comments.

Also, there is a fusible link on the unit.

That's good - it's what I was thinking of in my speculation about how the battery may be hooked up internally - it will protect against direct shorts. Lead-acid batteries have a very low internal resistance, so a wiring short could result in a very large current.

 

[metricus]

You want to avoid cycling those little 7.2Ah Batteries like that.

The battery is only there for power failures which are rare in my area. I ran it on battery only once to see how long it lasts in reality. At night when you also power the IR, the times will change. Did not test that yet.

When I abandoned the test, the voltage was still reading 12.1 so there was enough juice left.

Again, I am not running it any differently than most alarm panels out there.

 

[metricus]

If I had to do something like this I would use a charger that could be left on continuously and had a separate power supply to power the cameras, then have a relay switch over to the battery when mains power fails.

This is exactly what this PS does. During normal operation it powers the cameras. During power failure switches to battery. When power comes up it powers the cams and recharges the battery. It is all-in-one. Just like the alarm panels and the UPS. No homemade device.

All you have to do is make sure you do not put too many cams so you avoid a high discharge current when on power failure. In the same time you want to have enough to power the cams while charging the battery if it's depleted.

The reason for this post was to inform you that these PS exist and all you need is to calculate some amperage to make sure your circuit is balanced. Then measure voltage and discharge current to make sure your calculations are correct.

After you're done "throw" everything in an enclosure which may prove to be more expensive than the parts.

 

[metricus]

However at the same time, my NVR will die when the mains cuts out. So what I would rather do is have a small UPS, and install say a decent size deep cycle battery to keep everything (router, modem, NVR, phones, cameras, switches, firewall, etc) running.

I am glad you bring this point up!

One of the main strengths of my setup is that the cameras continue to record on the SD card. During power failure they work completely independent from the rest of the system. You may not be able to access them with no wifi but they still record.

I KNOW that there are many other solutions out there. This is my setup and I love it.

In my particular case there is an UPS that services the router, cable modem, IP phone, NAS etc. It is however at a long distance from where the cams are. The voltage drop on a 12 V line would be significant. This is why I preferred having a PS+backup right near the cameras.

 

[Michelin Man]

There's many way to skin a cat.

Technically the NVR runs on 12v but you need 52v for the POE section. I'm not sure what happens if I remove the whole inbuilt ethernet board as I don't use it, but the NVR will beep when you disconnect the 52v supply from the POE section.

So if you used an NVR without POE ports you can just run it from 12v.

Genuine ideas rarely come about, it is usually people who see what other people are doing and then draw ideas off that to make their own.

 

[metricus]

I don't have an NVR neither a POE system. I'm just a regular guy with a wifi router. These cams allow me to save bandwidth since they record on SD. I use bandwidth only when I stream to my phone. If I had a POE I wouldn't have bothered with 12V power supply+backup.
....or with ds-2532-iws