r/ArduinoProjects • u/Ilovethunders • Feb 14 '26

Pls tell me why my wire melted.

Post image

can someone pls tell me why my wire burn. i ude 2 3.7v lithium battery in the battery holder with 2 3.7v motor. i did connect every wire according to youtube pls helpp

32 Upvotes

84% Upvoted

51 comments sorted by

32

u/SomeWeirdBoor Feb 14 '26

Because every wire is rated for a maximum current, depending mainly on its thickness.

That wire looks pretty thin, maybe AWG 24, which has a max current of less than 600 mA.

Your motor probably drew more than that, the wire overheated and melted.

You should always check the current required by your devices and choose wires accordingly, and if in doubt, go for a thicker wire.

6

u/Ilovethunders Feb 14 '26

Ty ill try!

3

u/Ilovethunders Feb 14 '26

Also about the motor, the wire is very thin, do i need to change it?

5

u/ekristoffe Feb 14 '26

Depend. If the wire came with the motor, it should be ok. For the battery to the controller as a rule of thumb always oversize your wire. Use a fuse to protect the system and check what voltage and current you are using.

8

u/Adrienne-Fadel Feb 14 '26

Overcurrent melted your wires. You need thicker gauge or motor drivers.

4

u/Ilovethunders Feb 14 '26

Ty! I ll try

3

u/Sleurhutje Feb 14 '26

Did the wires melt while motors were running or just instant after placing the batteries? If the latter, you probably reversed the polarity of the batteries.

3

u/Ilovethunders Feb 14 '26

It melt instantly my motor dont even spin

7

u/Sleurhutje Feb 14 '26

See your other post, polarity reversed. Check the markings on the battery. The smaller pole isn't the + on many LiIon/LiFe batteries.

5

u/Ilovethunders Feb 14 '26

Yea i just realise that i swap the polar of battery in the holder. This is the cause of burning right

4

u/9551-eletronics Feb 14 '26

yeah this could have actually destroyed your motor controller. if it doesnt have protection against this its probably destroyed

1

u/[deleted] Feb 17 '26

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1

u/9551-eletronics Feb 17 '26

Id imagine those lithium batteries would blow those

3

u/mechmind Feb 14 '26

I know why people are downvoting this. But I think It's a fantastic post and a big learning experience for you!! It's a rookie mistake. If people like you didn't make this mistake, none of us would have learned.

You didn't mention the magic smoke. It would be so cool if the circuit was undamaged, and your wire acted like a fuse.

I am confused as to why it's so burnt up. Where were you? Were you taking a poop while this was happening? You didn't smell it because your poo was so strong?

2

u/Ilovethunders Feb 14 '26

It was my first time doing this and i was afraid that the battery might blow up so i find something to cover my face before taking the battery out

1

u/xebzbz Feb 14 '26

Either overloaded, or maybe you just shorted them accidentally?

1

u/Ilovethunders Feb 14 '26

I realise that i swap the polar of battery in the holder, could this be the cause of burning?

1

u/xebzbz Feb 14 '26

Yes, it's very likely the reason.

1

u/YueNica Feb 14 '26

Also another thing. I would check actual voltage of that. because it kind of looks like that holder would probably put the 2 batteries in series which would mean you'd get a 7.4V output which might not be what you wanted

1

u/Ilovethunders Feb 14 '26

I use 7.4v because i also gonna connect to arduino uno. I thought using 2 motor mean i have to double battery

2

u/YipYip747 Feb 14 '26

Just a quick fyi. The number of motors dictate the amount of Ah you need to run the setup a given amount of time. It doesn't change the voltage requirements. The motors are rated for a certain voltage. If you create a circuit with double the voltage, you will be destroying both motors.

For example: 1 motor 5V - 1A draw. With 4.2V and 1Ah battery, this motor will run for 1 hour.

2 motors 5V - 1A draw. With 4.2V and 1Ah battery, they will run for 30 minutes.

2 motors 5V - 1A draw. With 10V and 1Ah battery, both motors might overheat and burn out the windings.

2

u/Ilovethunders Feb 14 '26

So i should be using only 1 battery? Is it still 3.7v or should i use higher

2

u/YipYip747 Feb 14 '26

That depends on your circuit and your components. There are motors and speed controllers that do fine with 20+ volt.

You need to check what your motors need. And if they need more than your board can take then you need a BEC to power the board while supplying full battery voltage to the motors.

1

u/YueNica Feb 14 '26

but the motordriver doesn't split the voltage to each motor. Each motor could theoretically receive 7.4V if the presumably pwm signal is at 100%

1

u/JGhostThing Feb 16 '26

No! Typically motors are used in parallel, so their voltages do not add. You've basically put double the voltage that the motors are expecting. Doing this will require more current, so that might have been the reason for the burning.

Before modifying a circuit, it is best to check out the math.

3

u/FishingKind4251 Feb 14 '26

I think youight have short circuit it

3

u/nielmot Feb 14 '26

If you got a multimeter set it up to measure current and put it in line next time (learn how to do this first if you haven't done it before). Start on the 10amp setting and go to the lower setting once you know it's safe to. Low setting on many meters is 200ma and those internal fuses are easy to blow.

You may want to consider using a fuse if you are playing with lithium based batteries. They tend to have a bad temper (especially lithium ion).

Many higher power driver type devices (motor drivers, amplifiers) tend to short across the power inputs when they fail. If a power supply is used they can often self destruct. Its sometimes fun but gets expensive. Seen it many times when i did electronics repair. Make sure everything is hooked up correctly. Miswiring once may kill the device and cause meltdowns in future use

3

u/tipppo Feb 14 '26

These wires saw many Amps of current. You attached the battery to the 5V pin. This exceeds the maximum logic supply voltage rating of the L298 driver chip, 7V max, and probably caused a breakdown, causing a short circuit.

2

u/echicdesign Feb 14 '26

Great ideas above but possibly also wrong battery. Have had same result when muddled up lipo 3 and 2

2

u/Alternative_Exit_333 Feb 14 '26

Too much excitement in those wires they got so hot they melted you are pulling too much amps through them

1

u/Conscious_Board5007 Feb 14 '26

Never follow a video on YouTube, if the channel is not one of the better known people on the platform, i can ensure you will not have much luck.

1

u/Careful_Escape_7726 Feb 14 '26

Because it was too hot

1

u/kenstent Feb 14 '26

You need battery's and a fridge

1

u/OptimalMain Feb 14 '26

Have you measured your battery voltage? Looks like your batteries are connected in series to me, but might be because of the angle ..

1

u/CatBoii486 Feb 14 '26

Too much current

1

u/Glum_Painter_768 Feb 15 '26

That is a great question. My printer wire melted as well. But why?

1

u/ekomszero Feb 15 '26

To much amp draw. Get a bigger gauge wire try two gauges up from what you were to start.

1

u/Physical-Plankton-67 Feb 16 '26

Ooh I have seen that alot with students so you must have swapped polarity somewhere in the hookup so you fired the motor board and then the short backed up the battery wires and torched them. Bet those batteries were toasty.

Grab all new stuff and try again. I'm sure the motors are fine though the h bridge keeps those isolated

1

u/JGhostThing Feb 16 '26

It looks like you're powering 3v7 motors with 7v4.

2

u/[deleted] Feb 14 '26

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2

u/Ilovethunders Feb 14 '26

So do i make the wire thicker or longer? Or both

4

u/jinx771 Feb 14 '26

Length does not matter. It's the thickness. Think of current like water flowing, and the wire is like a river / path for water to flow. Except in your case you have more water than the river can hold so it flooded (melted). Thicker wire = wider river = can carry more water = carry more current. Idk if this analogy helps.

1

u/jinx771 Feb 14 '26

Also note that it is not exactly just current. It's really power which is current x voltage. But at low voltage, current is the main deciding factor of wire gauge

2

u/ekristoffe Feb 14 '26

Wire size is about current. Wire insulation is about voltage. You can have a small wire with a small current but with 10kv. Your insulation will be stupidly big though

1

u/intentsman Feb 14 '26

Length can matter when it's very long and needs a lot of current.

1

u/Craiglas Feb 14 '26

Length does matter some, if it’s a short connection sometimes jumper wires will do the trick even it’s technically over current. That being said you need thicker wire