Philo's solution to NXT batteries

Take a visit over to Philo's website to see a set of instructions for building a power-supply insert for the NXT brick that uses an AC power adapter to provide power to your bots. Not for the everyone (especially those of us with not-so-great electronics skills), but a great start for the hacks and homebrew fans.


Anonymous said…
Hi Phil,

Reading your story on battery life I have the following comment. For some time now also Lithium-Ion rechargeble AA (LR6) batteries exist on the market which do run on 1.5 Volts per cel. I use these for some years know and they are perfect. For example the brand Rayovac but there are also others. The advantage over the NmMh standaard is the 1.5 V instead of 1.2 Volts. It requires a different charger that can be purchased but these batteries are a good solution to the 1.5 Volt Non-rechargeble batteries without loss of power for the many of us. Check out the site of where I buy these 1.5 V Lithium Ion rechargeable AA's.

Regards from also a big Lego Mindstorms Fan, Franklin
Anonymous said…
It's me again. After reading my first comment concerning batteries and their use for the NXT I realised that I need to explain a bit more about these batteries. I made a little mistake. I was talking about these rechargeble 1.5 V batteries as being Li-Ion but in actual fact they are rechargeble 1.5 Alkaline batteries. I have been using the Rayovac brand for some years now for all my RCX units and the Motors that came with it. Phil, When I looked at your site about all the Lego Motors that saw light over the years I realised that I used these Rayovac 1.5 Volt Rechargeables successfully with these old motors also because their maximum current per motor was just around 120 mA. These special Alkaline rechargeables from Rayovac or Accucell have a current limit when unloading of about 350 mA. this was OK for the 3 moters on 1 old RCX but when looking at your charts about the new NXT motors I realised that there will probably be the big change with the NXT...these new motors are probably the best strong beasts I have seen since motors for radio controlled cars!!! They consume almost 4 times that of the old motors and weigh even much less?!...approx 500 mA?! max. This means that my succesfull use of this new rechargeable technology for RCX's probably is going to restrain me with the new NXT motors. You have done a Study on this from looking at your website...what is your opinion? Are these real maximum currents or would it still be possible to use this new Alcaline rechargeable technology? These new batteries have a limited rechargeable life but have no memory effect and even when, according to the brochure they can only be recharged 25 to 50 times for normal use and 100 times for very frequent use.. the cost of 1 set of 6 AA's for around 10 euro's would still mean that this is a much cheaper solution than buying non-rechargeable Duracells al the time. It is interesting though to talk about this topic for the NXT since even rechargeable battery technology is leaping forward every year. I hope that my comment triggers some more discussion about the LI-Ion pack that Lego is providing for the NXT education pack and the possible future for the Standard NXT box. perhaps some other new solutions are being born soon!!!

Many regards from a big dutch Lego and Mindstorms Fan...Franklin
Anonymous said…
Hello Franklin,

I have heard of Rayovac rechargeable alkaline cells for some time, but never tried them. Some people seem happy with them ( but current limitation (about 400mA from what I've seen) seems to be a real bummer for the NXT. I confirm that a single heavy loaded motor can consume up to 800 mA connected to NXT (up to 2A when directly powered from an external supply!), 600mA sustained.

Moreover I went to the website of Rayovac and of Conrad and found no mention of rechargeable alkaline batteries. Looks like they gave up on this product.

My opinion is that NiMH provide a good solution for all mobile NXT applications, except for the most demanding ones. At 7.2V the NXT+NXT motor deliver more work than a RCX with 2 parallel motor under 9V...

Anonymous said…
Hi Phil,

you may look for these numbers:

Anonymous said…
When I was younger I've always loved to make electrical robots out of lego but some how I've never seen it out on the market..
If it here on the market now, I am most definitely buying my son a set of lego's just so that can be my excuse! :)

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