I see, so how could I boost the voltage from a usb?

You need a boost converter.

There is a lot about this that I don't think you really understand yet. You need to do some reading and some searching. Bottom line, I think your best short-term solution is to remove the batteries and charge them in the charger you currently have.

 

? https://www.analog.com/media/en/technical-documentation/data-sheets/3124f.pdf

 

I actually have a dc/dc step up converter. But if I increase the voltage, wouldnt the amperage also go down? I read somewhere that that's how it works not exactly sure. I'm still new to all this.

 

That subject, including boost converters, seems to have been discussed here: https://forum.allaboutcircuits.com/...ttery-converts-to-9v-12v.168650/#post-1497564

Is this some game to fight boredom?

 

That subject, including boost converters, seems to have been discussed here: https://forum.allaboutcircuits.com/...ttery-converts-to-9v-12v.168650/#post-1497564

Is this some game to fight boredom?

Thank you for the link and what do you mean?

 

Conservation of energy - Wikipedia \(E_{IN_{MIN}}=E_{OUT_{MAX}}\quad ,\quad E_{IN}=E_{OUT}+E_{LOSSES}\quad ,\quad E=I·U=\frac{U^2}R=I^2R\)

modding the link ... https://forum.allaboutcircuits.com/...attery-converts-to-9v-12v.168650/post-1497564

 

https://en.wikipedia.org/wiki/Conservation_of_energy

This will help me understand how the dc to dc coverage works I assume? If so thank you.

 

I assume?

just keep asking questions as long you get your answers ... voltage conversion is a vast topic -- if you pinpoint your questions for speciffic converter I/O U,I ranges you will get more practical answers ... likely
create a check-list

1. is the USB input power limited
   1. YES - you only can charge the battery as fast
   2. NO - you can have more flexible design options
2. does your Li-Ion charger have any specific input requirements
   1. YES - you may need to set up cyclic charging --e.g.-- collect power to (super-)cap / charge Li-Ions
   2. NO - more stright forward approach
3. is the available space×budget×time limited
   1. YES - you need to fit your design accordingly / or add interface (cable) for external charger (e.g. power , feedback , control/status , ?etc. )
   2. NO - ...

 

just keep asking questions as long you get your answers ... voltage conversion is a vast topic -- if you pinpoint your questions for speciffic converter I/O U,I ranges you will get more practical answers ... likely

I see, I will.

 

On post #18 you show a photo of "the USB that was connected to the RC car". It is marked CHxxxx and 12.8V and has an inductor. Is that used to charge the 12V/500mAh battery in the car? Is there a black blob IC on the other side of the circuit board?

 

On post #18 you show a photo of "the USB that was connected to the RC car". It is marked CHxxxx and 12.8V and has an inductor. Is that used to charge the 12V/500mAh battery in the car? Is there a black blob IC on the other side of the circuit board?

Yes it is used to charge that battery you mentioned and the other side looks like this

 

The charger circuit in the car is also a proper voltage boost converter circuit.
What chemistry (Lithium or Ni-Cad) is the original 12V/500mAh battery? Maybe the original Charger circuit in the car can be used to boost the USB and charge 3 18650 Lithium-Ion or Li-PO battery cells, but the charging time will be maybe 15 hours or more.
3 Lithium battery cells charged in series should use a charger that is "balanced", but 3 cells are charged to 4.2V x 3= 12.6V so maybe the charger charging to only 12V will be fine.

 

https://www.amazon.com/12-8V-500mAh-Battery-Reverse-Racing/dp/B07Y7J4PFC this is the exact battery in the rc car.

I soldered one of these https://www.amazon.com/gp/product/B06XWSV89D/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1 to the end of a usb cable to charge the 3 cells and adjusted the potentiometer and monitored the voltage.

 

You have a voltage boost converter but you are missing a proper ordinary Lithium 3-cells balanced charger circuit.
Without a proper charger circuit then the lithium battery will probably explode (spectacular) and catch on fire.
The battery in the car has a LiFE04 battery that is different (its voltage is too high) to your ordinary 18650 Lithium-Ion cells.

 

You have a voltage boost converter but you are missing a proper ordinary Lithium 3-cells balanced charger circuit.
Without a proper charger circuit then the lithium battery will probably explode (spectacular) and catch on fire.
The battery in the car has a LiFE04 battery that is different (its voltage is too high) to your ordinary 18650 Lithium-Ion cells.

Lol I have been "charging" it that way for about 3 days now

Regardless, I searched up what you mentioned and I was wondering, I keep saying different versions with different values so what exactly would you recommend? Thanks a lot btw for the support!

 

A proper lithium battery charger is supposed to sense a full charge then shut off. Your overcharging will probably cause a nasty fire.
Hobby stores sell proper safe balanced chargers for ordinary Lithium batteries and also sell the batteries.
I have never seen the new version LiFE04 batteries or chargers that your car came with.

 

A proper lithium battery charger is supposed to sense a full charge then shut off. Your overcharging will probably cause a nasty fire.
Hobby stores sell proper safe balanced chargers for ordinary Lithium batteries and also sell the batteries.
I have never seen the new version LiFE04 batteries or chargers that your car came with.

This battery stuff is so overwhelming. And finding what fits is even more, I tried to do some research but it was too much indigestible information.

 

Also turns out my 18650 batteries are fake and unreliable

 

Would it be possible to use the battery that came with the rc car instead?

 

Also turns out my 18650 batteries are fake and unreliable

Explain in more detail what lead you to that decision