When you get a new rechargeable lithium battery pack, does anyone know how long we should charge it the first time? Thanks, Sonya On Wed, Oct 20, 2010 at 10:37 PM, Andy Traiger <[log in to unmask]> wrote: > Hey Jude, > > > > Be aware that alkaline batteries, which are the most common type of AA > battery, may not be the best to use for your robot. The reason is that the > six alkaline batteries when fully charged will have a voltage of 9.6 Volts. > As you’re using the robot and the batteries discharge, the voltage will > decrease fairly rapidly; even when the battery has a fair amount of capacity > left the voltage can droop significantly. The more they are discharged the > lower the voltage gets. Lithium batteries tend to hold their voltage more > stable as the batteries discharge. The Lithium batteries that are made for > the NXT brick will be 8.4 volts when fully charged. Comparing performance > over the same amount of time, the voltage of the Lithium battery will stay > stable while the alkaline voltage is drooping substantially. > > > > What does this mean to your robot performance? If you’re using alkaline > batteries, the motors will move faster than the Lithium when both are fully > charged. So, alkaline batteries can give your robot more power / speed when > they are fresh. However as the alkaline batteries discharge a bit the motor > performance will slow down. This will possibly lead to inconsistency in > running your missions. If the kids refined their missions when the voltage > was low, the robot may perform completely differently when a new set of > batteries is inserted. > > > > My team uses the Lego lithium battery pack. The kids on my team > periodically check the battery voltage as they are developing missions, > especially if they start seeing their missions failing. Use the NXT window > to view this while the brick is connected to the computer if using NXT_G. > Our team swaps the Lithium battery with a freshly charged one if the voltage > drops to about 8.1 Volts. > > > > All that being said, besides Alkaline there are other types of AA batteries > being sold (including even lithium batteries which are pretty expensive). > Each battery type will have different discharge characteristics. > > > > Andy > > > ------------------------------ > > *From:* First Lego League in Virginia and DC [mailto: > [log in to unmask]] *On Behalf Of *Jude Arulpragasam > *Sent:* Wednesday, October 20, 2010 9:48 AM > > *To:* [log in to unmask] > *Subject:* Re: [VADCFLL-L] NXT batery warning > > > > I would like to know if there is any advantage using re-chargeable battery > pack over individual AA batteries'? > I just bought new re-chargeable DC battery pack (NXT<http://www.legoeducation.us/store/detail.aspx?CategoryID=178&by=9&ID=1971&c=1&t=0&l=0>Rechargeable DC Battery (W979693)<http://www.legoeducation.us/store/detail.aspx?CategoryID=178&by=9&ID=1971&c=1&t=0&l=0> from > Lego website. > > Please give me some pros and cons on this > > Thanks > > Jude > > ------------------------------ > > Date: Tue, 19 Oct 2010 20:36:44 -0700 > From: [log in to unmask] > Subject: Re: [VADCFLL-L] NXT batery warning > To: [log in to unmask] > > Our team started using AA batteries instead of the rechargeable battery > pack. But when they had to change the batteries, they had dismantle the > robot to get to the battery compartment. I am worried that the kids will not > put back the robot perfectly, if they have to do this just before the > tournament to have fresh batteries in. Is that how it is normally done? > > thanks > Gaja > > > ------------------------------ > > *From:* Jerry Lorengo <[log in to unmask]> > *To:* [log in to unmask] > *Sent:* Fri, October 8, 2010 3:28:54 PM > *Subject:* Re: [VADCFLL-L] NXT batery warning > > Agreed - always use fresh AAs. > > > > The recharchable batter has a goofy memory and the voltage drop will make > reproducibility for missions almost impossible. > > Sent from my iPhone > > > On Oct 8, 2010, at 12:48 PM, Lloyd O'Hara <[log in to unmask]> wrote: > > We only use batteries and always make sure we have plenty on hand. > > > > Also, I'm sure why you would take 2 sets of four AA batteries, the nxt > takes six AA.. > > > > Lloyd > > ----- Original Message ----- > > *From:* Viquar Shaikh > > *To:* [log in to unmask] > > *Sent:* Friday, October 08, 2010 10:50 AM > > *Subject:* Re: [VADCFLL-L] NXT batery warning > > > > To add to this --- no matter what - we always carry 2 sets of four AA > batteries - one is a new packed set. This is a good backup for these > 'just-in-case' scenarios. > > > > Thanks > > Viquar > > On Fri, Oct 8, 2010 at 10:32 AM, Brandy bergenstock <[log in to unmask]> > wrote: > > This came across the Ga FLL yahoo group adn I thought it was important for > everyone to realize: > > The other day my team had taken one of their NXT bricks with them to a > meeting. When we got home, the battery was completely discharged. After > recharging it, my daughter discovered that the "Sleep" setting was at 60 > minutes. The brick had accidentally turned on during transport and since > the sleep setting was so long, it ran the battery down. We discovered that > the 60 minute setting is the default for both the 1.26 and 1.31 firmware > update. That is WAY too long! > > If you have updated your firmware, you should check the sleep setting and > change it is a more reasonable time (perhaps in the 2-5 minute time frame). > This way you won't accidentally run down your battery. I'd hate for someone > to discover their battery was dead when they arrived at a competition. > > To access the sleep setting on the NXT brick, go to: > > Settings > Sleep > and then change the time with the arrow buttons > > > ------------------------------ > > 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. > > ------------------------------ > > 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. > > > ------------------------------ > > 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. > ------------------------------ > 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. 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