Need some assistance please.
Complex has cameras at different locations and we are looking at some options to power them during outages. Eskom’s new truck is they claim to have 2.5 hour outages but these generally last much more than that.
So the NVR sits in the guardhouse but the problem is link to the cameras around the complex is over fiber and then there’s an Ont in each pole box with a poe switch and then 2 cameras. Poe runs off 48-57v so those router backup things will not work. It’s on a pole so there’s the space / weight limit. Cameras require around 7-10 w so that’s a total of 20w. Switch should use another 10-20w max including the Ont.
Any ideas for a cheap and efficient solution?
I was thinking of using some old 105A lead acid batteries but can’t find anything to mount these onto the pole and then there’s an inverter / charger that also needs to go somewhere.
How are these devices powered?
If you feed mains power to each pole box are the cameras fed power by the PoE switch??
There’s currently mains power at each pole. Ont has a 220 to 12v psu. Then the poe switch has its on 220 to ~50v psu. Data from Ont goes to switch. Cameras are connected directly to the poe switch.
This is the 24V PoE solution…
The 12V is simply sourced from the 24V via a DC-DC converter…!
The 48V version will require more batteries (or smaller) or a buck converter which I’m not a fan of.
What is the lowest voltage your cameras will operate with??
It may not be feasible, depending on the 220V is distributed.
But my first thought would be to consider a centralised solution would be to investigate how the 220V is fed to the poles. Perhaps circuits can be rearranged so that that 220V supply can be maintained.
It’s uses 802.3af so I guess it’s 45-57 V or thereabouts. I got some cameras for myself this past week and they have a separate 12V input as well. The complex ones are pretty old though.
Was driving to communica today and thought about a dc to dc boost regulator. Found a bit of a monster 600w one for R269. Will do some tests and see it it will work.
When the complex installed fiber a couple of years ago, they got the installer to run fiber to the cameras as well. It’s a relatively small complex of 39 free standing units and the road is about 1km within in a rectangle. AC for the cameras are just pulled from the closest units meter box.
Will be a bit of a mission to get a single 220 feed from the guardhouse. They will probably not agree to dig roads and driveways again, let alone the cost of cabling.
Got myself a small poe switch and will test with the boost regulator. If it’s fine, we can just install a battery, charger and use the regulator.
12v isn’t really a problem, even 24v for poe. I got one of those router type ups devices and it has 24v poe but the camera doesn’t work on that.
If my boost converter works, I’ll use it to power the switch and another router ups for the ont.
Those power bank type mini UPS’s are going to struggle to convert 3.7V to 24V (let alone 48V!)
I’m watching this space with interest…
These are referred to as boost converters (as opposed to buck converters)
So far so good.
1 camera running for 1h30 mins now and counting.
12v output from “micro ups” going into boost converter outputting 48v into poe switch. Data uplink of poe switch connected to my home router. Camera connected directly to poe port on switch.
Viewing the camera feed on a browser connecting directly to the camera ip.
So far ups hasn’t dropped a bar yet, still showing full. Tomorrow will test with 2 cameras and test mains failure / return and see how it behaves.
I was thinking of getting a battery and trickle charger but this seems a lot more simpler… if it works.
Mini ups rated 8800mah so probably has 4x18650 cells so probably about 30wh.
Dropped to 75% after 2 hours and down to 50% now after 3h40 minutes.
So it seems like I will need a larger capacity ups to get the cameras though a 3 hour outage.
Those two statements sound contradictory. I assumed the DC-DC converter from 24V down to 12V is also a buck converter?
There is no reason you cannot boost from 12V to 48V. Heck those small HF-design inverters boost 12V to 350V without breaking a sweat
Point taken! Boost converters are not my favourite…
The typical power bank backup (mini UPS) uses cells in parallel and then a boost converter to crank up the voltage to what is required.
So they use 3.7 V (nominal) and produce 24V or 48V…
If you have had experience with inverter UPSs that run on a single 7Ah battery you will understand my sentiments.
The SLA battery suppliers have a high current battery at double the price compared to an ‘alarm’ battery (which cannot be used in this application)
Not always true.
I’ve seen some in 2s and 2s2p.
I’ve seen some have a combination of a buck on the battery charging circuitry and a boost on the output.
Why do you dislike the buck/boost converters?
Most have a 12v outage and some have 15/24v poe lines but that’s really low power on those lines.
I’ve seen lithium battery becoming common these days in the same format as the typical 12v 7A sla. Had to get one the other day for the complex fence energizer.
Also came across an empty shell and looking for some old laptop batteries to reclaim some 18650 cells to build my own.
You can try something like this: power supply 12vdc 6.4a - Sherlotronics
With a 17AH battery. See Sherlo 6.4Amp - SHERLO-6AMP - Sherlotronics | Alarmtec (Pty) Ltd & Battery 18Ah | Alarmtec (Pty) Ltd.
They also have a standard 7AH one: Sherlo 3Amp - SHERLO-3AMP - Security Equipment | Alarmtec (Pty) Ltd
The output voltage is adjustable, so a Blue Nova or another “lead acid replacement” lithium battery could work well.
You would then still need to boost for the POE, something like this or this – just check that your cameras are compatible (unable to find something local).
I think this will work well, but I don’t think if fits the “cheap” requirement.
The devices I’m familiar with that use 4x18650 cells are the same design as the power banks that are used to charge your cellphone (5V)
They use a boost converter to generate the 5V but it’s a low step up in voltage so it handles it comfortably.
If the same design is used to generate 12V it’s a much bigger step up in voltage and this requires much higher current from the cells.
The reason they use this design is so they don’t need a BMS with equalization…