Re: NXT Brick Low Battery Problem
The original FTC / Tetrix prototype used 2 x 7.2V batteries and the external battery low voltage indicators were not changed until version 1.44 to reflect the single 12V battey that is shipping with the kit. This explains the frequent "low battery display" with the 1.43 release that shipped on the CD with the FTC kits.
In version 1.43 and earlier, the low battery pop up warned for both the internal battery and the external battery. For version 1.44, it was changed to occur only for the internal battery. Yes, it is desirable to also generate for external battery but I didn't have one yet to test so I disabled the check.
There is an easy way to adjust the sensitivity of the low battery popup. There's a couple of fields in the "System Parameters" debugger related to this that you can fine tune. I think you have to be in "Expert" Menu Level to get this particular debugger window.
- the variable is "low voltage battery count limit" and represents the number of contiguous low voltage values that need to occur to trigger the popup display on the LCD. Try increasing this value and it may eliminate transients. I recall that a value of '0' will disable the popup display totally.
- "muxLowBatteryShutdown" is a low voltage limit for the external battery used to disable the motors. It should be set to around 10000 which will display as 10.0 V. It looks like it currently reflects 12.0 V which is a value appropriate to the older 14.4 V battery level. This will be automatically changed in next release of ROBOTC (version 1.45). This check is designed to protect against excessive discharge of the battery which will dramatically shorten its life.I recommend everyone make this change.
Both of above values are stored in flash memory. So they only have to be set once per firmware download.