Pin on White rechargeable batteries

[tabbycatrobots]

While pondering my NXT failure after battery recharging (see topic "Motor and Sensor ports dead after recharging"),
I noticed that matching the location of a small pin shape protruding from the white rechargeable battery is what looks
like a small black button switch in the NXT battery compartment. It is where the + symbol is molded into the plastic
for the 4th from top AA battery. Are there any specs on if this is a switch and if so, what it does? Thanks for
any info.
Howard

[h-g-t]

I believe this pin lets the NXT know that the LEGO battery is fitted.

No idea what the NXT does with the info!

[gloomyandy]

The Lego firmware uses this button/pin to change the calculations it makes about how full the battery is. The NXT only measures battery voltage and as the rechargeable pack provides a lower voltage then standard AA cells even when fully charged the firmware needs to know that the pack is in use so that it can show a battery full/empty symbol correctly...

[sparramc]

I believe this pin lets the NXT know that the LEGO battery is fitted.

No idea what the NXT does with the info!

Yes this is correct. The switch is part of the LEGO Rechargable Battery Detection Circuit. Please see Attachment for clarification.

LEGO MINDSTORMS NXT hardware schematic.pdf

LEGO MINDSTORMS NXT Hardware Schematic

(145.06 KiB) Downloaded 658 times

[tabbycatrobots]

Thanks to all for the info.
Howard