Introduction: NiMH Batteries Charger Logger

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This is an experimental charger and data logger for NiMH batteries and packs, to get data and graphics about the charging process.

It uses the RD6006 power supply and the UD18 Digital tester (optional). It is implemented as node-red flow.

For the full story and all documentation, you can see the repository: https://github.com/msillano/NiMH_charger_logger

In the photos: the user interface, and graphs by OpenOffice (via CSV files) of slow and fast charges.

Supplies

RD6006 - RD official store: https://it.aliexpress.com/item/4000282551930.html + power supply + case

UD18 many, e.g. Banggood

Step 1: Circuit (simple)

Really very simple: I do it using USB-crocodile cables.

This project uses the RD6006-W (not in battery mode) as Constant Current or Tension generator and as V/I/Ah/Temperature meter, while a UD18 can be used only as autonomous HW protection in the fast charge mode.

Step 2: Node-red Flow

  1. A WAMP (or LAMP, or ...) is required to have mySQL and phpMyAdmin.
  2. Add to the node-red ‘palette’ the packages: node-red-node-serialport, node-red-node-mysql, node-red-contrib-modbus, node-red-contrib-ring-buffer.
  3. Copy the contents of the file charger2.json to the clipboard and import it into a new flow in node-red.
  4. Update 'configuration nodes': 'batteries' for mySQL and 'RD6006' for MODBUS serial.
  5. The file charger2.sql contains the mySQL db definitions. Import it using phpMyAdmin.

The UD18 is totally independent: the required values are show in the right pane (after start) and the UD18 can be set from UI via Bluetooth (see https://github.com/msillano/UD18-protocol-and-node-red for details) or directly using the HW buttons. It is never read.

Data are stored every 10 seconds, as CSV file or in MySQL tables.

Some default values are defined in Config node and the user can change it.

This charger works in following modes:

  • Static Test to appreciate VRD, Vb, Ri, Tbatt, deltaT as function of Ic only.
  • Tickle charge (C/20...C/40), safe for any time.
  • Constant tension, a special tickle charge for 3 x battery pack, see https://github.com/msillano/e3DHW-PMS/blob/master/e3dhw-pms-intro_en.pdf .
  • Slow charge (C/10: 15h overnight charger) is safe, and time can be the unique termination method.
  • Fast charge (C/3.3...C: 5h...1.5h charger) requires at least a temperature termination test.

In the photos: the node-red flow and a static test.