According to Lego, the Mindstorms battery should be good for over 500 charging cycles. If you're recharging it once a week, that's about 10 years. These batteries do wear out from corrosion and chemical changes as well, though, so I wouldn't expect one to last that long. You can check the charge level of the battery from within the NXT programming environment. If recharging brings the battery voltage to a reasonable level, close to 9V, and the level doesn't drop rapidly as the robot is being used, then the battery's probably OK. If you're going to buy a new battery, be sure to recycle the old one. Ralph On 5/16/10 1:26 PM, Sonya Shaver wrote: > I have no information as I am seriously battery-challenged. But I > wanted to add that I would love to know also. I think that from what > others have said, it seems like after a couple of years the > rechargeable battery doesn't work as well anymore. It kind of wears > down and doesn't charge as well over time. We are entering Year 3 > with our current robot and battery, so I was thinking about buying a > new battery before the start of the season. I don't honestly notice > any difference in the performance of our battery as of yet, however, I > don't want to have chaos in the middle of the season! So I thought > maybe starting with a fresh battery would be better. > > So, I would love to know also! > > best, > Sonya Shaver in Harriosnburg > > > On Sun, May 16, 2010 at 8:10 AM, Eric Palmer <[log in to unmask] > <mailto:[log in to unmask]>> wrote: > > It appears as if Lego has a new recharable battery with 2100mAh of > power > compared with the original 1400 mAh > > > At the first site for team registration, products page there is a > battery > charger and battery listed this way > > --- NEW BATTERY --- > > Rechargeable AC Battery > * US 979798 > * $54.95 USD > Description: > > This battery is for robots purchased prior to the Body Forward season. > > And there is a charger listed the same way. > The lego Education Store lists this original batter this way > This rechargeable lithium battery is designed for use with the NXT > Intelligent Brick. The battery features 1400 mAh of power and an > A/C plug > for direct power supply. The battery will charge from 0 to full in > a maximum > of four hours. Use the 979833 AC Adapter to charge the battery (sold > separately). > > > --- ORIGINAL BATTERY --- > Then there is another battery and charger listed this way > > Rechargeable DC Battery > * US 979693 > * $54.95 USD > > The above one is a NEW Battery that the Lego Education Store > describes this > way > > Designed for use with the NXT Intelligent Brick, this lithium ion > polymer > battery with DC plug gives you an alternative to normal AA > batteries. The > battery features 2100 mAh of power and uses the Transformer 10V DC > (778887) > to charge. Estimated recharge time: 4-5 hours. Is not compatible > with the AC > Charger (979833). > > > > The description on the FIRST site leads us to believe that the new > battery > can't be used with the older NXT bricks. But the Lego Education > site just > explains that the chargers have to be matched up. > > > Does anyone have any additional information on these batteries? > > Thanks > --- > Eric F. Palmer > [log in to unmask] <mailto:[log in to unmask]> > > -- To UNSUBSCRIBE or CHANGE your settings, please visit > https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join > or leave the list". > > -- VADCFLL administrative announcements are sent via > VADCFLL-ADMIN-L. Visit > https://listserv.jmu.edu/archives/vadcfll-admin-l.html to subscribe. > > > ------------------------------------------------------------------------ > To UNSUBSCRIBE or CHANGE your settings, please visit > https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or > leave the list". > VADCFLL administrative announcements are sent via VADCFLL-ADMIN-L. > Visit https://listserv.jmu.edu/archives/vadcfll-admin-l.html to > subscribe. -- Ralph F Grove, PhD Professor, Graduate Director James Madison University Department of Computer Science -- To UNSUBSCRIBE or CHANGE your settings, please visit https://listserv.jmu.edu/archives/vadcfll-l.html and select "Join or leave the list". -- VADCFLL administrative announcements are sent via VADCFLL-ADMIN-L. Visit https://listserv.jmu.edu/archives/vadcfll-admin-l.html to subscribe.