Distributing battery power to multiple components

Is this a commercial project ?

I ask because my first advice is for you to pay some one to sort this out !

It looks as if you will almost certainly need at least one DC-DC convertor to make the right supplies for the cameras and lights but I would need to see the actual specs of the items to be sure. The stepper motor will need some kind of controller (perhaps you are already allowing for that.)

Any way you don't want to blow up any of this stuff and you easily could.

MK

Michael, I really wish it was a commercial project (as I'd love nothing more than for a company to pay for someone to do it), but it's more of a personal research thing.

As for the stepper motor, I'm using an Arduino unit to run it, if that's what you were referencing.

I think this is going to take a while to figure out...

Hi Stephen  It is important to get the voltages right. If the voltages are right the current will follow. When you have a power source marked 12V 6 A they are telling you that the supply has 12 volts of potential. This voltage will cause different amounts of current to flow in a circuit depending on the resistance of the circuit. The 6A tells us that eveything will work fine as long as the circuit has more than 2 ohms of resistance. 12 volts accross 2 ohms of resistance will cause 6 amps to flow. If the resistance in the circuit is less than 2 ohms the power supply will try to supply more than 6 amps which may exceed its ability and something will overheat or a fuse will blow. You can get a rough idea if your power supply has enough power for all you applications by calculating its wattage. Multiply the Volts by the Amps. In my example above we get 12V X 6A which gives us 72 watts. If you know the voltage and current demands of the things you want to hook up to the power supply you can multiply their voltages and currents to also obtain their watts. If you add up all the watts used by the things you want to hook up to the power supply they have to add to less than the wattage of the power supply. If you have to convert to different voltages to run your periferal equipment then you will also use up some of the powersupply's power (watts) to make the conversion. From your physics it is a consequence of the 2nd law of thermodynamics.  I wasn't clear on your question regarding the jacks on the side of the panel whether are they power supply outputs or are they where you supply power to the unit. If they are power supply outputs then you have 25 Watts on the 5V  5A, 60Watts on the 12V, 5A, and 120 Watts on the 24V 5 A jack. This should give you adequate power to run the voltage regulators or converters necessary to power your periferals.

@ John, It could easily not be enough power - the two computers need 120W (but at 12V not 24V) , the cameras and lights need unknown amounts of power, possibly at odd voltages so there may be conversion losses.

@ Stephen, could you post the details of the computers, cameras and lights so we can work out exactly what volts and amps they need. (Sometimes things like cameras work with a 7.2V battery or equally happily with 12V, sometimes not - you have to check the spec.)

MK

Michael you are correct. After I shut down last night I began to rethink what I had said. In addition even if  Stephen can get the power he needs the source is a 24 volt 20Ah battery which will be quickly drained. Granted the 12V 5A for the computers is probably the rating on the power supplies and not the actual current draw of the computers. If these are laptop computers they should have their own batteries that could also contribute to the power resources. You are right though, to go any further analyzing this question we will need more information. It does look like the stepper can be grouped with the computers on a 12 volt supply and the others will work off a common 8 volt supply so there shouldn't be to much complexity.

Stephen, what are your plans for using the device? How long do you need it to run before recharging the battery? Does it need to be portable or can you use a power supply connected to your power grid? Are the computers laptops with their own internal batteries?

John

John, these are power supply outlets, redirecting the power from the battery, so your total watts assertion is correct. Your first line about the current following if the voltages are correct, really helped to put me at ease. None of the items are going to draw more than 5 amps, so I'm hoping I'll be okay.

Michael, I've taken a look at the specs of the items that I can and they're listed below:

PC 1:

9.1 Absolute Maximum Ratings Operating the Intense PC under conditions beyond its absolute maximum ratings may damage the device. Absolute maximum ratings are limiting values to be considered individually when all other parameters are within their specified operating ranges. Functional operation and specification compliance under any absolute maximum condition, or after exposure to any of these conditions, are not guaranteed or implied. Exposure may affect device reliability.

 

Table 34 – Absolute Maximum Ratings

Parameter Min Typ. Max Unit Main power supply voltage 8.5 - 16 V

 

9.2 Recommended Operating Conditions Operating conditions include parameters that are under the control of the user: power-supply voltage and ambient temperature. The Intense PC meets all performance specifications when used within the recommended operating conditions, unless otherwise noted.

 

Table 35 – Recommended Operating Condition

Parameter Min Typ. Max Unit Main power supply voltage 10 12 15 V

NEEWER CN-160 Video Light:

Total Power: 9.6 watts

Voltage range 7.4 ~ 8.4 V

Based on the 9.6 watt total power, the current draw will be ~1.1 to 1.3A.

Cameras are a bit of a problem, as I only know they need 8.1V. Max power draw isn't listed anywhere that I can find, so I'm flying blind there. The specs of the included battery are (min)7.2V, 875mAh and will take up to 480 shots, so from that I think I can conservatively estimate that each camera will use south of 2A max.

As for the stepper motor driver, it's good up to 30V, drawing no more than 2-4 amps (when I tested it with a multimeter). I've been running it at 11.1V off of a hobby battery, so 12V should work just fine.

Adding it all up:

Computers: 120

Lights: 28.8

Cameras: 48 (Conservative best guess)

Stepper motor: 48

Total: ~250 Watts

EDIT:

John, I'm trying to fashion together a machine for taking pictures remotely and stitching them together on the fly. It does need to be portable and the computers aren't laptops. There's a link to one of them, up above and the other is a clone, so I have no specs, although it's less powerful that the specs on the one listed above. I'd like the battery to ideally last for a few hours. It's not going to be running full throttle all the time, but it may be snapping pictures quite often.

Currently, the battery that powers the robot and the computer, runs a good while before it needs to be recharged. Perhaps a day or two, with the use being more occasional.

Seems we are making some progress. Based on the information you sent on the cameras I think you are high on your power usage estimate for them. I would guess they are using a fraction of an amp when they are idling and slightly more when they take a picture. The camera batteries have a capacity of 6.3 watt hours (Voltage X mAh )and if they last for 480 pictures you can figure that you are only using 0.013 watt hours of power per picture. This tells me that the cameras are almost negligible compared to the 60 watt computers. You also have the fact that some of your power demand is intermittant.  It will be important that you use a switching power converter when you bring your voltage down to the 8 volt level so that you do not loose a lot of your power to heat in the conversion. There are some nice adjustable switching power regulators available for practically nothing. In the final analysis you may want to go empirical and set things up and just see how long the main battery lasts. If it doesn't last as long as needed you can tackle the problem of adding an additional battery or two.

I think this will link to an example of the DC to DC converter you may want to use:   DC DC Adjustable Voltage CC CV Buck Converter 7 32V to 0 8 28V 12A 300W | eBay

Why not use a CMOS computer?  Are you running a RTOS?

I think the computers are PCs (the clue was in "Operating the Intense PC ......", so I reckon he'll be running a full blown OS.

BTW - how many microprocessors/micro-controllers aren't CMOS ?

MK

I was thinking along the lines of something like this:

https://www.gumstix.com/