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Ben Brown

Electronics and Embedded Systems Engineering

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eBike monitor

The eBike monitor concept is to provide a HUD for the energy information for eBikes. The unit consits of a small colour LCD screen that can be mounted on the handlebars or whereever you wish, and a monitoring pcb that is installed inside of the battery pack.

Concept

The system works by having the battery monitoring and statistics calculations performed on a small pcb that is mounted inside of the battery pack. This board stays ‘paired’ with that battery for the life of the battery (the boards can be re-used later on).

Monitoring unit

The monitor board lives on the battery itself as it measures the actual capacity of the battery and learns its distint discharge curve. This allows for 1% accuracy in the readings of SOC (State of Charge). Dont worry about the current consumption, the board runs on around 200μA when active, and < 50μA when in sleep mode (no current flowing). By having the monitoring mounted in the battery, we can monitor the charge as well as the discharge cycle of the battery, even if it is an extremely slow or fast charger.

HUD

The HUD unit allows for setting up and calibrating each monitoring board, either by the onscreen menus or by the USB connection. In normal use the screen shows an overview page that details the current power consumption, run time remaining and SOC.

The HUD optionally comes with a small amount of internal memory, that can also be upgraded at purchase time. The internal memory allows datalogging of the power usage on the bike. By combining this with the ability to have a GPS mounted inside, the datalogging can be time and location stamped (this also allows speed view on the screen).

Features

  • Monitor battery voltage and current (and thus power)
  • Accurate SOC readings for the battery (not guessing on voltage!)
  • Runtime prediction based on current power usage (similar to how laptops predict)
  • Datalogging of power usage over time
  • GPS for speed and datalogging

Planned Features

  • Support RTC module for timestamping
  • Temperature monitoring and alarms
  • Throttle pre-processing to impliment power envelope and thermal limiting

Note: This product is still in development, so this information is only as accurate as of current, later blog posts may over-ride this information (or provide more)