From The robot supplier - notes on battery care.  from:

XBC Battery Care

A short history of NiMH batteries.

The XBC contains a Nickel Metal Hydride (NiMH) battery pack. This pack contains 6 cells and runs at 7.2 volts. NiMH technology was developed by the Michigan based company Ovonic Battery, a division of ECD Ovonics. The Company was founded in the 1950’s by Physicist Stanley Ovshinsky, and the battery branch was founded in 1982. The first NiMH batteries were sold to the public in 1983. Ovonic Battery currently holds patents in 17 countries for the NiMH battery.

Care and Maintenance of you XBC’s Batteries

The first time you use your XBC the batteries will need to be cycled. Cycling means charging the XBC fully and then letting it run down until it dies. This cycle will need to be repeated 3-5 times to allow the batteries to reach their full capacity. Normally NiMH batteries will heat up during charging and can get as hot as 130 degrees Fahrenheit. After charging, allow the batteries to cool before use. For maximum performance, the batteries should reach their peak charge right before use. Ideally, the batteries should not remain fully charged for longer than necessary. After heavy use, it is good to discharge the batteries by letting the XBC run until it dies. After the XBC has died, fully recharge the batteries with in the next week to maintain optimum performance. The XBC battery pack will last through 500 charges and depending on the care and conditions can last as many as 1000 charges. The NiMH batteries have little or no memory so it is possible to charge the batteries at any time regardless of the current charge of the batteries without adverse effects.

If your batteries need to be stored for more than two weeks, make sure that the batteries have at least a 50% charge and are stored in a cool dry place. The NiMH batteries self discharge at about a rate of 1% per day. If the batteries reach 0% charge the capacity is diminished. The batteries reach their optimum performance between 30 and 100 degrees Fahrenheit, with 40-60 degrees yielding the best results. As a rule of thumb, the higher the temperature, the shorter the charge is held. After storage the batteries will run “flat”, or not hold a charge as well. The batteries just need to be cycled a few times to restore performance. The XBC can be run dead 2-3 times a day with out any negative effects. Just make sure that the battery pack has cooled down after being charged.

Class Lecture Notes

First Lecture

Robot control/teleoperation

handyboard notes

handyboard sensors

XBC/IC notes

XBC sensors.

Biological Foundations of the reactive paradigm

Reactive Robots

General Sensors

Designing Reactive Robots 

Color Vision

Vision extra slides.

hybrid robots

multirobot quickie

representing space

representing space complete

Navigation Part II

Social Robotics I
Social Robotics II
More on MultiRobots for the grads
The last lecture (coming soon in robotics)