Lithium Ion Batteries for Robotics. Part 1
This article discusses LiIon batteries and describes a universal Lithium Ion battery charger with a Smart Battery interface based on an Atmel ATMEGA8 microcontroller using GCC ver. 3.2
Lithium Ion batteries are becoming a practical alternative for robot power. After my robots sealed lead acid battery passed away recently I started looking for a replacement. I took a quick look on EBay and there was a 10.8V 4500 mAh Lithium Ion laptop battery for $20 that I could not resist. This battery has twice the capacity of my sealed lead acid and was 2/3 the price. I later purchased a Gateway 11.1V 6400 mAH battery for $25. Getting my batteries operational vaulted me into a whole new world which has culminated in the Universal Lithium Ion Battery Charger board described in this article.
These batteries really work very well. My robot seems to run forever without requiring a recharge. Alas, all is not perfect however.
Here's what I now know about Lithium Ion (LiIon) batteries:
The Not so Good
The biggest issue is the battery charger. There are some chargers available but they match certain batteries which tend to be very expensive. Many laptops have an internal charger and external chargers are not available. Some batteries cannot be charged at all without a charger that is talking to them in the right dialect. Unless you are lucky enough to find a battery with matching charger you need to either build your own or buy a very expensive universal charger.
This article really describes two separate but related technologies: lithium ion battery charging and Smart Battery communications. Either can exist without the other but they are often found together.
Here is a picture of the complete charging system. That's my temperature transmitter board mounted on the LiIon battery.
To be continued
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