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I have a 12v 15amp power supply, and I have 5 appliances. I want to build this circuit in parallel, so voltage here is constant.(12v)So i’m not going to mention voltages. The first appliance uses 10 amps.The 2nd uses 2 amps. And the 3rd, 4th, and 5th each use 1 amp. How would I distribute the current so that each appliance gets what is required? I thought of a way, It would probably work theoretically but maybe not practically. In other words I’m not sure it’ll work. I thought of taking 15 wires, and soldering them to the positive terminal, do the same for the negative terminal. So right now each wire is carrying 1 amp. Then, I would take 10 of these wires (10 positive and 10 negative of course) and connect them to my first appliance which uses 10 amps. Then connect 2 wires to my 2nd appliance, and 1 wire each to my 3rd, 4th, 5th appliances. Will this work? Thanks in advance, Mitch

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Why don’t you just get wires that can handle more current? Then you just need 5 wires rather than 15 of them. You don’t have to worry about dividing up current. The appliances will just draw however much current they need as long as you have enough of it.

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Mitch: Hello. If you hook up a 12V power supply to several loads (appliances) in parallel (that part is critical), each load will draw the correct amount of current it requires. As long as your power supply is rated to handle the total current load of all items attached to it, you should not have any issues. Your wiring should be rated to carry at least 3-4 times the current being drawn through it. You may want to watch this to learn more about basic DC circuits. 2. Basic DC Series Circuit - YouTube

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Here is a video that covers parallel circuits: Parallel and Series Resistor Circuit Analysis Worked Example using Ohm's Law Reduction | Doc Physics - YouTube

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Hi Mitch,

if the voltage is fixed

the total current amount will depend only on the load requirements (as long as the power supply can maintain that power)

for example for your application : 12V, 15A, you need a 180W power supply.

If you got at least this power supply unit and you put it in parallel with all your 5 loads, each of them will suck the current needed because the voltage generator only fixes the voltage. The current depends on loads.

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If you want to be able to build a circuit with a degree of control over the current I would go with transistors. For the 10 amp line you’ll need at least a 15 amp transistor shown here: TIP3055 15A 15 Amp 60V Transistor NPN Vintage | West Florida Components for the other power lines you could buy a few of these guys: TIP120 Darlington Transistor | Jameco Electronics. Once your done just follow a normal guide for using transistors to crontrol current and you are good to go.

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Hi,

Thanks for replying,

Will each load draw the amount of current it needs even if I’m not using a board that distributes power?

Basically, what you guys are saying is that i can connect a load that uses 2 amps max to a power supply 12v @ 15 amps and the load will take only what it needs to work, without getting “overpowered” and burning?

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Hi,

Thanks for replying,

Will each load draw the amount of current it needs even if I’m not using a board that distributes power?

Basically, what you guys are saying is that i can connect a load that uses 2 amps max to a power supply 12v @ 15 amps and the load will take only what it needs to work, without getting “overpowered” and burning?

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Hi,

Thanks for replying,

Will each load draw the amount of current it needs even if I’m not using a board that distributes power?

Basically, what you guys are saying is that i can connect a load that uses 2 amps max to a power supply 12v @ 15 amps and the load will take only what it needs to work, without getting “overpowered” and burning?

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That is correct. Typically the only way something could be “burned out” by a power supply is if the voltage is too high, not the amperage.

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Thank you so much to those who replied. I really appreciate the time and effort you guys give to help rookies like me :slight_smile:

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That’s true. You have to imagine the voltage as a tank filled of water and the loads as tubes of different size coming out of the tank. They won’t take away

more water that they can handle.

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I agree too, my initial reply assumed that you wanted to ensure that you can’t go over a certain current threshold. This would be good to protect devices which might for example short circuit and want to draw more than the amperage it can take causing the device to burn out.

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the answer to your question is not a device or technic that limits or suplies the right amount of current but understanding how the amount of current gets there.

The amount of current each device draws is a function of their resistance and the voltage you put on it.
for example, if you measure 1,2ohm resistance and put 12Volt over it that would mean that 10Amp would flow through.
if you would put 24volt on that same device 20Amp would flow trough and if the device isn’t rated for that amount it would probably get to hot, smoke or go boom.
now if for example you would measure 6ohm resistance and put 12V over it that would mean 2Amp would flow through
So you see you can understand how much each (static) device requires just by measuring the resistance of the circuit.
There are also switching elements like transistors that would give you a false reading because it can open and close a circuit changing your measurment.
but for most dc elements like for example a heating element you can measure it this way to make sure how much current will flow trough.

to beter understand what voltage, amp rating you need or how much amp an device will use there are 3 very simple sums.
get familiar with ohms law
https://learn.sparkfun.com/tutorials/voltage-current-resistance-and-ohms-law
basically if you know 2 values these sums will give you the answer to the third:
V=I*R
I=V/R
R=V/I

important note: get thick enough wires, you don’t want them to get hot or melt.
make sure they are always rated higher than the amount of current that is actually going to flow trough them.

also it is always wise to have a power supply that is rated for more amp than al devices combined require.
if you try to pull 15Amp from a 15Amp rated power supply chances are you might blow a fuse, the voltage might drop or a short-circuit protector might kick in. so if you need 15Amp its better to have a 20Amp power supply. :wink:

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exactly.
because of the amount of resistance to current flow each load draw the amount of current it needs.
changing the voltage higher and more current will flow even with the same amount of resistance.
so you can control the amount of current by changing the voltage, or if you change a circuits resistance.

but don’t try to change the amount of current with wires because a wire has basically zero resistance and will not limit your current flow *except for maybe melting and burning till it breaks…

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Ok, Thanks for helping I learnt a lot!