Mommy's golfcart doesn't have a usable fuel gauge (battery level meter), or a clock. I have fixed that.

Dash, clock offdash, clock on

I slapped an Adafruit OLED (same as on my skateboard) onto a Particle Photon. I used a simple voltage divider to split the ~56v battery string down to something measurable, and a 48V relay to turn on/off a lower-voltage (~18V) line to power the voltage regulator.

The Photon awesomely has a very simple battery backup connection (so there's a lithium battery in there too), and the clock awesomely syncs up whenever it finds the cloud.

clock view

The display currently shows a fuel gauge bar, under that it has raw ADC value (debugging), a calculated voltage level, and a symbol showing the device's state of connectivity -- z (sleeping), + (connecting), * (connected). The device doesn't like being disconnected generally, so I detect that state and disconnect manually. It will reconnect on power-up, or if it senses the cart being charged (e.g. in my garage).

The clock display uses the built-in font, has a blinking cursor (currently "off"), and a smaller seconds display (also for debugging).

The code is a little silly, but please This email address is being protected from spambots. You need JavaScript enabled to view it. if you want to try and make one, I'll hook you up.

Tell your device what to do!

Turn the LED on.
Turn the LED off.

1.95x2.00 inch (49.53x50.80 mm) 2 layer board.

A new hardware project: Crazy Volts. Drew and I are working on a fuel gauge for his Crazy Cart. It's based on the ATmega328P + Adafruit's OLED display, and a custom PCB to hold it all together.

The power switch for the cart has 3 leads: ground, battery, and switched to controller. The controller lead is switched and provides the voltage sense, so we just wired the input + power leads together. The display running in the pic above shows our calibration test, and the display itself hasn't been permanently mounted yet.

The design is general enough to be adapted to anything with batteries. In software we'll probably only try to estimate the power characteristics of SLA, but it's just software....

2 layer board of 1.55x2.05 inches (39.47x52.15 mm).

We also considered using a general-purpose ATmega328 breakout (the bduino), or a teensy 3.1 + adapter board to wire up a regulator + OLED display.

I am out of kits and will not restock Wiiceiver due to the lack of good wireless nunchucks available. I am working on Wiiceiver X, a replacement wireless handheld controller & receiver, and can hopefully release specs & instructions in the Spring.

I am also out of "upgrade" kits, but you can also download the latest software and upgrade your own device at your convenience.

Introducing the wiiceiver! A drop-in "plug and play" replacement for a traditional RC receiver, designed for use on an electric skateboard. It has 2 standard 3-pin servo connectors (single ESC, dual ESC, or ESC + BEC) and a port for a Nintendo Wii Nunchuck.

... unfortunately all kits are sold out.

Looking for instructions? click here

I have been asked to deliver a low-voltage disconnect circuit for potential future production. It would drive a 15w load and protect a 12v sealed lead-acid (SLA) battery.


  • Arduino-based ATtiny45v microcontroller
  • preset high/low values at 11.3v and 10.5v
  • An asynchronous banner/Flasher to expose the observed ADC value

I have (finally) made a proper PCB and am offering an LVD / battery saver kit.

This is based on the Custom Arduino-based LVD, but incorporates a 60A N-channel MOSFET. For simplicity's sake, this has a single MOSFET for switching on the ground side. While the components are rated high, it's probably best for relatively low draw (~5A). For high-draw components you can easily use the LVD to fire an automotive electromechanical relay and drive as much current as you like!