Cell ph 5v power source from RC car battery?

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Cell ph 5v power source from RC car battery?

floydie

439 posts

Ultimate Geek
+1 received by user: 37

Topic # 204255 23-Sep-2016 14:45

Id like to make a simple 5v power adaptor plug so i can charge a cell ph from any rc car battery such as a 2s lipo battery.

ideally id like it all to solder up so i have a usb port and XT60 connector with the regulator all resin'd into one compact hard case adaptor...

whats a suitable 5v regulator chip that can handle say 3 amps plus so it will carry the required current without extra transistors etc?

RunningMan

5269 posts

Uber Geek
+1 received by user: 1750

Reply # 1639458 23-Sep-2016 14:56

What about using a cigarette lighter USB charger as a starting point?

floydie

439 posts

Ultimate Geek
+1 received by user: 37

Reply # 1639466 23-Sep-2016 15:01

The RC car batteries are only 7.4-8.4volts and id like to keep it compact as possible.imagine a usb socket soldered back to back with an XT60 connector and a reg chip in the middle somehow

ideally id like to use just one chip such as maybe a LM123 chip?

RunningMan

5269 posts

Uber Geek
+1 received by user: 1750

Reply # 1639468 23-Sep-2016 15:05

Are they a TO3 package? Regulator like that may need to dissipate a lot of heat into a heatsink if pulling several amps through it...

floydie

439 posts

Ultimate Geek
+1 received by user: 37

Reply # 1639470 23-Sep-2016 15:07

tbh not sure.. id prefer a TO220 package..it just needs to be able to charge a cell phone such as a galaxy S5

geocom

530 posts

Ultimate Geek
+1 received by user: 123

Subscriber

Reply # 1639501 23-Sep-2016 16:03

Why not just use a UBEC for the regulation?

Geoff E

hio77

'That VDSL Cat'
9276 posts

Uber Geek
+1 received by user: 2072

Trusted

Spark

Subscriber

Reply # 1639507 23-Sep-2016 16:15

Given that you wanna use a XT60 connector, i would simply use a readily available package like so https://www.aliexpress.com/item/Dual-USB-Output.....

#include <std_disclaimer>

Any comments made are personal opinion and do not reflect directly on the position my current or past employers may have.

richms

21738 posts

Uber Geek
+1 received by user: 4521

Trusted

Subscriber

Reply # 1639523 23-Sep-2016 16:34

2S will not work into one of those. Will start off OK but somewhere around 7V they start to oscillate on and off, and the phone will show charging but really nothing is happening. There are other designs that will deal with it but the car ciggy lighter chargers are not made to have that low of a differential.

3S or more and will be fine.

As it is something that will be left alone I would also want something with battery management as well, low currents so you could just run the whole thing from the ballance plug.

Richard rich.ms

floydie

439 posts

Ultimate Geek
+1 received by user: 37

Reply # 1639610 23-Sep-2016 21:07

geocom:

Why not just use a UBEC for the regulation?

i did consider a UBEC but initially dismissed it as i remember them being pricey...will have another look

geocom

530 posts

Ultimate Geek
+1 received by user: 123

Subscriber

Reply # 1639619 23-Sep-2016 21:16

Hobbyking have them for ~$10 USD. They also have a product that is very similar to what you want to do. http://www.hobbyking.com/hobbyking/store/__60455__Turnigy_USB_Power_Adapter.html 2.5A though and not 3A

Geoff E

richms

21738 posts

Uber Geek
+1 received by user: 4521

Trusted

Subscriber

Reply # 1639632 23-Sep-2016 21:43

Even says 7v on it so don't know how it would cope with a 2s down all the way.

Richard rich.ms

linw

1949 posts

Uber Geek
+1 received by user: 388

Subscriber

Reply # 1639778 24-Sep-2016 11:35

geocom:

Hobbyking have them for ~$10 USD. They also have a product that is very similar to what you want to do. http://www.hobbyking.com/hobbyking/store/__60455__Turnigy_USB_Power_Adapter.html 2.5A though and not 3A

Really strange coincidence as I was thinking along the lines of the OP. My phone is also an S5!

The HobbyKing device is perfect for the job. I have plenty of 3-4 cell Lipos.