[Al Skierkiewicz]

Frank,
There are a variety of factors that change the internal resistance of the battery but for our applicataion, consider the .011 ohm spec to hold true for most of the life of the battery and under most discharge conditions. If you take a look at the discharge curves you will see that the terminal voltage falls below the 12 volts mark almost from the start and you can easily determine that 100 amps flowing across .011 ohms will produce a 1.1 volt drop inside the battery. Remove the load and the battery will return to 12 volts since you are measuring "open circuit" voltage. (Without current flowing, there can be no voltage drop.)

The critical point for the battery is when 'under load' the terminal voltage falls below 8 volts for any length of time. It is at this point that the RC goes into stanby mode, the backup battery takes over the processor and all PWM outputs are disabled. If the main battery quickly returns to normal voltage then the RC wakes up and starts to function until the supply again falls below 8 volts. By watching the wiring resistance between the main battery and the RC and keeping it to a minimum, the critical 8 volt point will be less of a problem.

If you watch the battery voltage monitor on your OI you will see that rarely will the battery voltage be 12 volts while running. Get in the habit of having your drivers keep the OI in battery monitor so that they can tell when the RC is getting to the 8 volt point. It is not unusual for the OI to display 10-11 or even less than 9 volts for most of the match if you are running full out. You might even see short periods where the OI will read 5 or 6 volts without shutdown.