NiMH Batteries and Netduinos

The robot is pretty hard on batteries so I figured I would get some rechargables. (Eveready NiMH from Countdown on special every so often)

Charger (includes 4 AA batteries) NZD 24.69 + Batteries AA NZD 12.99

First thing I noticed was the Robot getting a bit more random than usual, then the backlight of the LCD on the QuakeZure stand alone demo kit stopped working. Using a multimeter I found that straight off the charger the batteries were 1.4v which then rapidly fell to the 1.2V as per the label (should have paid more attention to the label).
The batteries also do get quite hot charging.
The Magician chassis comes with a 4 x AA battery holder so the Netduino (or LCD display) was getting less than 5V under load and was browning out.
Hence the upgrade to the 6xAA battery pack for the robot. The SeeedStudio motor shield has a 5V regulator on board to ensure the Netduino isn’t fried.

My Robot – No tools required

A few local people have asked for a BoM for my robot.  This is for the entry level version with no soldering or additional tools required. (There is a screw driver included with the robot chassis kit)

2WD Robot chassis from Mindkits – NZD25

Netduino from Mindkits – NZD58

IR Distance Sensor and cable from SeeedStudio– USD 14

Motor Controller from SeeedStudio – USD 20

Mountings for IR Sensor from Mindkits – NZD 5

bracket x 2

screws x4

nuts x 2

With the Seeedstudio motor controller I use a larger battery pack –

Battery holder 6xAA NZD2.25

Battery snap NZD0.75

If you don’t mind some soldering or crimping …

Short range ID Distance sensor from Mindkits NZD 25.50

I swapped the long range Sharp sensor for the short range one.

Magician robot

Robot on my desk

Make sure you upgrade Netduino to 4.2 or later for improved PWM