These are very good suggestions except #2. Assuming you have an XBee and not XBee-PRO, it actually draws MORE current in receive than transmit, so reducing transmit power (whose max is 1mW anyway) will make no difference. It sounds to me as though it is probably drawing more than it should be. At these current levels (about 50uA) even a slight mistake or oversight could swamp the 50uA with a much higher quiescent current. I definitely do not think that a 9V battery would be a good idea for long-term use, as their energy density is poor and you probably won't find a linear regulator which would have low enough quiescent current (and of course, as you pointed out, it would waste at least 2/3 of its power). Is there a microcontroller or something else in your circuit besides the XBee? The extra drain could be due to that. Sean On 7/13/07, alan smith wrote: > 1. Have you tried talking to Maxstream live chat about this? > 2. Have you tried reducing power (tx power on the Xbee)? > 3. Have you actually measured the current draw when your up and alive? Are you sure > the module is asleep? What else is in your circuit besides the Xbee? What is your > quiesent current draw when its asleep? > 4. You can do a efficient battery boost circuit, where the input can drop quite low and you boost to 3V. Lots of design examples from LT and others. > > Rafael Vidal Aroca wrote: > > Hi people, > > i'm playing with these great ZigBee modules from Maxstream (XBEE). > They are really interesting and powerful.. > > My problem is related to battery life. > > According to the manufacturer battery life calculator available at: > > http://www.maxstream.net/support/battery-life-calculator.xls > > i could have a life of more than 3 years depending on the conditions > i use my modules. Well, my conditions are quite good: > > - The module is in sleep all the time, waking up each 4 minutes, > sampling ADC ports, transmitting data, and going back to sleep > > Theorically i should get at least a year, but when i tested it, my > batteries did not last for 2 months! I'm using 2 alcaline AA batteries > which gives 3V. > > Well, seems like the batteries still have energy, but their tension > has gone to less than 2,7v, which will not power XBEE. > > The problem, is that there are no commercial batteries available > with 2000mAh and 3 ou 3,3V with low voltage drops in the long time. > > Some engineers suggested me 9v batteries with a voltage regulator. > > Is it a good idea? Won't i loose too much in the voltage conversion > (9-3=6v). At 50mA i'll spend 300mW just to drop the voltage??? > > Well, i really don't know how to manage the batteries to give me 2 > years of life to my little remote sensor. > > Does anyone have any idea or clue? > > thanks a lot > > Rafael > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > > > --------------------------------- > Fussy? Opinionated? Impossible to please? Perfect. Join Yahoo!'s user panel and lay it on us. > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist