Hi,
I am trying to build a small go Kart for my 3 years old daughter.
The motor is a typical 12V DC and consume up to 300mA.
The laptop battery supply 10.8V/4400mAh.
To power the arduino I connected the battery to a step down converter LM2596 and LM317.
Surprisingly, when I connect the battery the LM317's capacitor exploded and the LM2596 burned.
Why that's happened? Is it safe to use a laptop battery to power a DC motors?

 

Perfectly safe to use laptop batteries as they are usually lithium-ion, and need to be monitored for discharging.

 

Best guess is that you connected the battery backwards.

 

I checked the polarity with multimeter, so I am sure the connection is fine.
I had an idea to add a resistor between the + junction, but I don't know how to calculate which resistor is needed.

 

The only alternative explanation seems to be that the LM2596 and capacitor were defective. improperly installed, in the case of the capacitor used well above its voltage rating.

If the resistor you mentioned was to go between the battery and the regulators, there would be no need since the regulators can accept much higher voltages than the battery voltage.

The LM2596 might still be ok. If you see a big crack in the package that would be a bad sign. You might check again but carefully.

What is your plan now that the board has burned, if you can't bring it back to life?

 

I ordered a XL4016 300W 10A buck converter, which should handle high voltage and current.
Do you think it's a good idea to use a laptop battery?

 

300 Watts for a 35 watt application. That sounds like plenty of margin!

Perfectly safe to use laptop batteries as they are usually lithium-ion, and need to be monitored for discharging.

Dodgydave thinks so, and he probably knows more about batteries than I.

It would probably be good if Dodgydave elaborated on what he meant by "...and need to be monitored for discharging."

 

Hi,
I am trying to build a small go Kart for my 3 years old daughter.
The motor is a typical 12V DC and consume up to 300mA.

I have doubts a 4 watt motor is going to move much of anything at a speed that will even be fun for a small child.
If it was me I would be looking at repurposing a automotive windshield motor or old cordless drill motor.

300 Watts for a 35 watt application. That sounds like plenty of margin!

In my old school math ways 12 x .3 = 3.6 is not 35.

 

In my old school math ways 12 x .3 = 3.6 is not 35.

Apparently you have not learned Common Core Math, but I stand corrected. I think 99% margin is more than enough. I hope the regulator can run ok virtually unloaded.

 

12V @ 300mA motor? What are you driving with this thing? A mousetrap?

 

Apparently you have not learned Common Core Math, but I stand corrected. I think 99% margin is more than enough. I hope the regulator can run ok virtually unloaded.

My math was from pre mid n90's and my math teacher back then was a angry burned out idiot drunk. That fact I can use any math at all is a wonder.

 

300 Watts for a 35 watt application. That sounds like plenty of margin!



Dodgydave thinks so, and he probably knows more about batteries than I.

It would probably be good if Dodgydave elaborated on what he meant by "...and need to be monitored for discharging."

To elaborate on these 18650 cells, they don't like going beyond their lowest limits.as they then take more current than needed and self terminate!!, so ideally they need to be used with a battery monitor pcb.

 

LM2596 Hows he boosting with that 12 volt motor 10 volt battery

To get 12 volts out you have to have more then 12 volts in it's not a boost regulator

 

Thanks guys for your responds. It's one of my first projects so I am just trying my luck and learn on the way.
My brother is a mechanic engineer and he said that the motor should be fine for my goal (extremely low speed)
In my previous projects I only used Raspberry pi or arduino so I powered them with a standard phone power bank.
I only want to know if anyone already tried it, and share tips with me.
Thanks again

 

(extremely low speed)

At 3.6W you'll be lucky to get more than 1 mile per week .