Did You Know That Batteries Can Flip Polarity?

Were you aware that batteries can flip their polarities? I wasn’t. Fran Blanche discovered this while testing some Rayovacs that have been in the Star Trek Comm Panel that she hacked years ago.

Fran discover that one of 3 AA batteries in the toy had switched polarity. In the comments EEVBlog wrote:

Yep, this can happen if you have non-matched cells in series, or one dodgy one. The lower charge one discharges first and then the others in series push current through and reverse charge the dead one.

Many products have a warning not to mix fresh and used cells for this reason. This has popped up quite a few times in my videos over the years.

And, are Lithium cells vulnerable to this, too? FellenXD writes:

Very much so, and it can lead to growth of lithium metal crystals that can puncture the insulating membranes in the battery. This will cause a short circuit inside the battery and can lead to some explosive spontaneous self-dissasembly 🙂

Proper battery packs have balancing circuitry for the cells and a low voltage cutoff, which should stop this from happening.


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, TinyGO, or even use the Arduino IDE. Circuit Playground Express is the newest and best Circuit Playground board, with support for CircuitPython, MakeCode, 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 32,000+ makers on Adafruit’s Discord channels and be part of the community! http://adafru.it/discord

Have an amazing project to share? The Electronics Show and Tell is every Wednesday at 7pm ET! To join, head over to YouTube and check out the show’s live chat – we’ll post the link there.

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/

CircuitPython – The easiest way to program microcontrollers – CircuitPython.org


Maker Business — A development to watch: Intel in Ohio

Wearables — Seal the dEaL with this project tip

Electronics — Breadboarding Wire

Python for Microcontrollers — Python on Microcontrollers Newsletter: CircuitPython 7.3.0 RC0 Out and Much More! #Python #CircuitPython @micropython @ThePSF

Adafruit IoT Monthly — Detecting Water Pollution, Smart Girder, and more!

Microsoft MakeCode — MakeCode Thank You!

EYE on NPI — Maxim’s Himalaya uSLIC Step-Down Power Module #EyeOnNPI @maximintegrated @digikey

New Products – Adafruit Industries – Makers, hackers, artists, designers and engineers! — New Products 5/18/2022 Feat. Adafruit NAU7802 24-Bit ADC – STEMMA QT / Qwiic!

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.