0

Standby current of a USB car charger

NewImage

Ever wondered if leaving your car charger plugged in will drain your battery? Big Mess o’ Wires investigates and finds out.

How much current does a typical USB car charger consume, when nothing is charging? Zero? Microamps? Milliamps? Is it enough to be concerned about draining the car’s battery? There’s no better way to find the answer than direct measurement, so let’s go!

My 2016 Mazda CX-5 has two built-in USB ports, which can theoretically recharge my mobile phone while I’m driving around, but the rate of charge is so slow as to be nearly useless. In an hour of driving, it might raise the phone’s charge level by 15%. To get faster charging, I purchased a USB car charger that fits in the 12V jack in the car’s center console: the ubiquitous jack that was once the cigarette lighter in years gone by, but has now been repurposed as a place to plug in dash cams, DVD players, and other car accessories.

The new USB car charger works fine, and can recharge my phone from zero in about an hour, but it leaves me with a lingering worry. The 12V jack in the 2016 Mazda is not switched by the ignition, but is powered all the time regardless of whether the car is on or off. That means when the car is sitting parked, with the engine off, the USB charger is still drawing current. If I were foolish enough to leave some power-hungry appliance connected, it could quickly drain the car’s battery. But even with nothing connected, the USB charger will still draw some standby current. To measure it, I put together a quick test involving a 12V wall supply, the USB charger, a multimeter, and lots of alligator clips.

Read more.


Stop breadboarding and soldering – start making immediately! Adafruit’s Circuit Playground is jam-packed with LEDs, sensors, buttons, alligator clip pads and more. Build projects with Circuit Playground in a few minutes with the drag-and-drop MakeCode programming site, learn computer science using the CS Discoveries class on code.org, jump into CircuitPython to learn Python and hardware together, or even use Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for MakeCode, CircuitPython, and Arduino. It has a powerful processor, 10 NeoPixels, mini speaker, InfraRed receive and transmit, two buttons, a switch, 14 alligator clip pads, and lots of sensors: capacitive touch, IR proximity, temperature, light, motion and sound. A whole wide world of electronics and coding is waiting for you, and it fits in the palm of your hand.

Join 10,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

CircuitPython 2019!

Have an amazing project to share? Join the SHOW-AND-TELL every Wednesday night at 7:30pm ET on Google+ Hangouts.

Join us every Wednesday night at 8pm ET for Ask an Engineer!

Follow Adafruit on Instagram for top secret new products, behinds the scenes and more https://www.instagram.com/adafruit/


Maker Business — The sustainability of open source software

Wearables — The final environment

Electronics — Voltage drop from cables

Biohacking — Three DIY Photobioreactor Designs for Algae Growing

Python for Microcontrollers — Python snakes its way to Codecademy, beta 7, games, calculators, turning 6 and more! #Python #Adafruit #CircuitPython @circuitpython @micropython @ThePSF @Adafruit

Get the only spam-free daily newsletter about wearables, running a "maker business", electronic tips and more! Subscribe at AdafruitDaily.com !



No Comments

No comments yet.

Sorry, the comment form is closed at this time.