Stalker V2 + GPRS Shield + XBee Pro

Hi Guys,

I’m wanting to put together some sensor nodes for a proof-of-concept test for a customer using:

  • Seeeduino Stalker - Waterproof Solar Kit
  • GPRS Shield
  • XBee Pro S2B

Will the XBee and the GPRS module fit onto the Stalker PCB at the same time and will it all fit into the box properly?

Will the single LiPo Battery power the lot?

What other considerations should we be aware of?


Alex Shepherd

Hi Alex,

I play myself with Stalker v2 with attached XBee S2 (standard with cons approx. 40mA, not Pro) sending data from balkony to another part of the flat, where is another “receving” Arduino Mega. I live in the middle of Europe and I started with one 1W solar panel without any solar tracking. Stalker actually sends data every cca 17 seconds and I don’t switch on/off Xbee between transmitions. Orientation of the panel allows to receive sun rays from early morning till approx. 1400hrs now during the summer time. If there is clear sky the 1W panel is able to re-charge the 1850mAh Lipo to full within above mentioned period. But if there is cloudly the Lipo voltage is kept so so during the day and it is dropping down during the night.

So the next step is actually 2pcs of 1W panels in parallel connnection which re-charge the Lipo’s lost energy within 2-3hrs when clear sky, and add 100-200mVolt during the day when ovecast. But this is now, in summer. I’m afraid it can’t work in the winter time independently from 2 solar panels without external re-charging.

So now I’m preparing the panel with 4pcs of 1W solar panels and we will see. Nevermind this is experience with one XBee module only. I know that I can still improve a bit Stalker’ consumptoin both in hardware and software way.

The consumption in your case will be higher with GPRS and energy balance will depend mainly on meteo conditions at sensor’s place.

So that’s my experience with Stalker and solar panels for the last two months …

Cheers for now

Hi Vladimir,

Thanks for the feedback.

Our application will be sensing/logging data in a rural environment so hopefully we will be able to orient the solar panel to make good use of the Sun. Also we will probably put the node into sleep mode for considerable periods of time to conserve battery power and only ever transmit over GPRS once per day or even once per week. We anticipate one node will be the Coordinator that collects data from multiple sensor only nodes that will only have a single XBee module without a GPRS module and use ZigBee Mesh networking to link up to the Coordinator node. So they should be fine if they sleep for long periods of time in between samples.


Alex Shepherd

Hi Alex,

it sounds well. If I wrote about the posibilities how to more conserve the energy I thought also put XBee into sleep mode. It can be done in SW way and also to use the “hardware” possibilities of Stalker and new library. Nevermind if you intend to use on-board RTC chip RX8025 for it please read another topic in the same forum. RX8025 stucks very often and get the date/time data out of this chip seems to be quite unrealiable.

All the best