The New Battery Monitor

The Electronics

These consist of: a Control unit, an Interface unit, and a console display.

The Prototype Control Unit

The Control unit contains the Arduino modules and connector to the display and control buttons. The Control unit connects only to the Interface unit.

The interface Unit with the isolated Power supply.

The Interface unit connects to the current shunts and the batteries. It contains the components for the battery voltage sensing circuitry and the drivers for the Traffic lights.

The Traffic Light Display

This will mount on the domestic console.

When I moor up for the night and stop the engine, I expect a solid green LED. A full Battery.

As the battery discharges the LEDS will go Green, then Green/Amber, then just Amber at 50% of capacity.

If a steady Red LED comes on with the amber, the battery has dropped below 11.8 volts, and a steady Red LED alone means the battery is in trouble at less than 11.0 v

In the morning I start the engine.

Flashing Red means we are charging, at Bulk, with a voltage of less than 10.5v

Flashing Red and Amber means we are at Bulk Charge with a voltage of less than 13v

Flashing Amber means we have reached Absorption voltage, but with heavy charge.

Flashing Amber and Green means the battery is charging, and is getting close to full

A flashing Green LED means the battery is full, and I can stop the engine.

Th original intention was to put all the electronic in one unit, but the only nice box I could find for the display and controls isn’t big enough for all the electronics. Especially as I keep adding bits to the electronics.

Control unit

parts list
  • Case including control buttons: from here https://www.tindie.com/products/pancalculus/16×2-lcd-enclosure-with-buttons-for-arduino-uno/?pt=ac_prod_search OR here: https://www.ebay.co.uk/itm/20×4-LCD-enclosure-project-case-for-Arduino-UNO-Mega-Including-six-buttons/123450331161 for about £15
  • Display 20×4 Hobbytronics https://www.hobbytronics.co.uk/lcd/lcd-displays-5v/lcd-20-4-backlight-blue for £12.98
  • Arduino Mega from Hobbytronics https://www.hobbytronics.co.uk/arduino/arduino-mega-2560 for £33.48
  • Arduino Ethernet bridge from RS comp https://uk.rs-online.com/web/p/processor-microcontroller-development-kits/8732285/ for £21.94
  • Total £83.40

The Interface Unit

parts list
  • Case RS 505-549 ABS enclosure £3.74
  • Power unit
  • strip board RS 433-826 £12.53
  • voltage regulator RS 809-6361 £4.42 (for 10)
  • trimmer 5KΩ RS 522-0215 £3.74 (for 2)
  • resistors 2.7KΩ RS125-1161 £2.44 (for 20)
  • terminals
  • Total