Two cameras, one hardwire kit

[Jez]

I thought a new thread would be helpful to generate some more discussion on this topic. I've done a search but can't find much. I have fairly basic electronics knowledge so if you can contribute on this subject then it would also help others who may be asking the same question.

The question is whether you can just look at output current of the hardwire kits, and the power consumption of the cameras that you would like to install. Another question is whether it is safe to run the hardwire kits near (or at) their maximum rated output current.

Blackvue Power Magic Pro - Output current of 1A, max 2A.
I've seen one person has installed four cameras using a Blackvue power magic pro and splitters (https://dashcamtalk.com/forum/threa...ra-post-your-pictures.502/page-28#post-143554) This seems like it's on the edge because most cams draw about 500mA.

An analogy for me would be that speakers have a nominal power output, eg. 50W, and a maximum power rating, eg.100W. If you continuously put 100W through the speakers then it's likely that you will cause damage. Does this logic not apply to running a hardwire kit continuously near its maximum rated current?

Lukas LK 350 - Output current "Not higher than 1A"
I couldn't find the nominal output current for the LK 350. But if the maximum is 1A then it doesn't seem suitable to run two cams (and definitely not suitable if they are drawing more than 500mA each)

Multi safer - Max current of 8A
This should be suitable to run as many dash cams as you'd like.
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My situation:
I will be installing a Street Guardian SGZC12RC and a Mobius C2.

The 12RC draws approx 500mA (https://dashcamtalk.com/forum/threads/sgzc12rc-power-consumption.15326/)
The Mobius draws approx 500mA when charging battery and recording (http://www.rcgroups.com/forums/showthread.php?t=1904559&page=101)

So is it as simple as buying a hardwire kit which delivers a minimum of 1A rated current, and 2A max current?

The mobius instructions do say to use a charger capable of delivering 1A, and I assume a hardwired kit with a max current of 2A would be suitable for this.

 

[albertson]

In general, I agree. If the rating is only for maximum output, then de-rating the maximum output to near 50% for continuous use. This is only a guess.
Plan the location to allow some airflow around the electrical box for cooling.
Three more considerations:
How much power does the device consume on it's own. Not so easy to find in the specs.
Does it cut off early enough to leave you enough cranking energy in cold weather.
Is your battery strong to provide enough "park mode" run time to make this effective protection?
You may have the option to replace the car's battery with one with significantly higher capacity. Depends on the car.

I do not trust the voltage cut-off level of most of these devices. I have chosen to add a smaller second automotive battery to my wife's car and my daughter's. This second battery powers the 2 dash cams. You also need a battery isolator. The second battery is charged by the alternator while you drive the car. Assumes you drive for at least 20 - 30 minutes per day.
This does require careful installation of the second battery, so this is not a practical choice for many people. Modifying your car may not be legal to do in your country. A shop that installs car sound system could install the auxiliary battery if you want to use that option.
There are several battery isolators available.
I like this one. http://www.colehersee.com/home/smart_battery_isolators
The cams have the capacity of two batteries, until they both drop to 12.7 volts. At this point the batteries are separated, but the dash cams continue running but only using the auxiliary battery, until it's voltage falls below the camera's operating voltage limit.

 

[Jez]

Hi albertson,

I think you're correct - 50% may be industry wide for a continuous safe current relative to the maximum rated current of a device. Another consideration is the splitter. If you buy a splitter that can only deliver 500mA per socket, then you might continuously be running each socket near its maximum which is not ideal (or potentially dangerous?)

In terms of how much current the cameras draw, unfortunately the only information we have is what people have posted online, or possibly by contacting manufacturers. However I think a ballpark figure for most single channel cams is 500mA.

I would definitely buy a hardwire kit that allows for high cut off voltages. Some of the kits that do not allow you to set the cut off voltage and they have a pre-defined cut off of 11.8V. It is not good for a car battery to regularly be drained to this level and I think in some cases (especially winter), a car would not start. I've seen a thread where someone had a similar problem. He had a power magic pro and had to increase the cut off voltage.

What you have implemented with a second battery is a good way round this but I think it adds a lot more cost and complexity than most people would like. If we just knew a bit more about these hardwire kits, installed them in-line with their safe continous current, and set them to 12, 12.2 or even 12.4v cut off then I don't foresee any issues.

 

[Jez]

The splitters definitely needs consideration.

Ones like this have no output current specified, so I would say avoid. https://www.ebay.co.uk/itm/261574930894
This one specifies 500mA output current, so also avoid. https://www.ebay.co.uk/itm/111814641204
This one specifies 1A output current per socket, so looks good. https://www.ebay.co.uk/itm/351384095767
Who knows why this one can output 10A? lol

http://www.maplin.co.uk/p/24v-twin-cigarette-socket-adapter-a61jb

Maybe I'm over thinking this but I want it done right and done safely. I wonder how many people using two dash cams are overloading their hardwire kits or splitters, or underpowering their cameras which can also lead to problems.

 

[Ralph2]

Blackvue Power Magic Pro - Output current of 1A, max 2A.
I've seen one person has installed four cameras using a Blackvue power magic pro and splitters (https://dashcamtalk.com/forum/threa...ra-post-your-pictures.502/page-28#post-143554) This seems like it's on the edge because most cams draw about 500mA.

An analogy for me would be that speakers have a nominal power output, eg. 50W, and a maximum power rating, eg.100W. If you continuously put 100W through the speakers then it's likely that you will cause damage. Does this logic not apply to running a hardwire kit continuously near its maximum rated current?

Without a duty rating I would say that if it says max 2A then it should be able to continuously run under that load. It.. is, after all only an electronic switch. With electricity I think the concern is heat build up and running at max one would want to make sure it ( the PMP) is well ventilated. I do not think your analogy of speakers running at max and the current running through a switch is the same.. but I am far from an electrical engineer

 

[Jez]

Hi Ralph,

You may be right - an analogy to speaker output power might not be accurate. However if the manufacturer specifies an output current of 1A, but a max current of 2A then I would be hesitant to continuously draw a current of 2A through the device. Maybe it's completely safe, but if so I would have expected the manufacturer to simply specify an output current of 2A. But I'm no electrical engineer either

 

[wozzzzza]

if its power rating you are worried about of the units you want, don't be, if you think you are getting close to the rating of the unit with the cameras you want to run off of it just stick a relay on the output of the unit, that way the unit will only be powering the relay, about 100mA, and contacts of the relay, up to 20A depending on the relay used, will be powering the dashcams.
that's what I would do, that's what I have done for the 4 dashcams I run.

 

[Jez]

if its power rating you are worried about of the units you want, don't be, if you think you are getting close to the rating of the unit with the cameras you want to run off of it just stick a relay on the output of the unit, that way the unit will only be powering the relay, about 100mA, and contacts of the relay, up to 20A depending on the relay used, will be powering the dashcams.
that's what I would do, that's what I have done for the 4 dashcams I run.

Thanks mate, a relay is an option yes. What I'm wondering though, is what's the difference between the rated output current of an electrical device, compared to its maximum operating current? Is it safe to continuously run a device near its maximum operating current?

 

[Street Guardian USA]

Two devices off one MotoPark multi safer / fine safer is no problem. I have two SGZC12RC's hooked up to one via cig splitter in a mustang.
https://dashcamtalk.com/forum/threa...ony-exmor-imx322-wdr.8500/page-33#post-151447

 

[wozzzzza]

Thanks mate, a relay is an option yes. What I'm wondering though, is what's the difference between the rated output current of an electrical device, compared to its maximum operating current? Is it safe to continuously run a device near its maximum operating current?

rated output is the maximum current it can continually handle without blowing up, the maximum output is the maximum it can handle temporarily without blowing up I think if I remember correctly. e.g. the startup current of something is always more than its operating current.

 

[Hombré]

The cigarette lighter in this new car has a cover on it that says 12V-10A which is nice.

 

[Jez]

Two devices off one MotoPark multi safer / fine safer is no problem. I have two SGZC12RC's hooked up to one via cig splitter in a mustang.
https://dashcamtalk.com/forum/threa...ony-exmor-imx322-wdr.8500/page-33#post-151447

Hi Pier, as I said in the first post the multi-safer has a rated current of 8A which is very good. Unfortunately I would like a device which has a cut off of 12.4v which I think is more suited to a cold winter in the UK. The multi-safer goes down to 12.2v (and 6 hours).

rated output is the maximum current it can continually handle without blowing up, the maximum output is the maximum it can handle temporarily without blowing up I think if I remember correctly. e.g. the startup current of something is always more than its operating current.

lol...nice terminology. I think you are correct, the startup current may be higher. I know this is true for motors, which require a high current to overcome the breakaway torque/friction to get a motor moving. Whether it applies to static electrical circuits I do not know.

The cigarette lighter in this new car has a cover on it that says 12V-10A which is nice.

The rated output of your cigarette lighter socket has no impact on a hardwired BDP device.