Hi everyone,
I have to say this is a great forum and thanks for all the responses. I've found little interest in some other non-Arduino forums. I'll try to reply to each point separately.
fornsix
We're tracking dingoes and wild dogs, which are always on the move just about. I guess it would depend on how sensitive the movement "switch" was in terms of extending battery life. For example, if it switches on with head movements, it might never get a rest. If it can be tailored to trigger upon a certain degree of movement, it may well result in some savings. Thoughts?
kg4wsv
I should have qualified my earlier point that the SF logger actually already allows NMEA sentences to be partially restricted to pretty much only those sentences that you want. As far as we can tell, it's not possible to only store parts of sentences though (i.e. it's either a whole sentence or nothing). There are also some issues with the way the data is stored when it comes to importing into something like a spreadsheet app., but this is more of a pain then a major problem. It would be great if we could chop and change individual sentences to get exactly what we want without a lot of messing around, but it is probably easier to do this at the end of a given deployment using existing GPS applications rather than trying to program the board to do it in the field. You're right that the Energizer AAs have more capacity than the 123s, but weight is a bit of an issue for some of our projects. The case we're using in an upcoming project is too small to fit AAs, or even three/four AAAs, but the stocky nature of the 123s, coupled with the fact that we only need two, means we can "cheat" a little and embed the batteries on the side of the case using epoxy and still keep the weight down. The case has to be top-mounted to the collar because the SF loggers have an integrated antenna. Even if they didn't though, I actually like the top-mount, because trying to fit/adjust collars in the field and dealing with a length of coax (or something similar) leading to an antenna is a nightmare. To stop the collar from spinning around, we mount a collar drop-off device and a few other components near the bottom side, which all adds to a little more weight than the GPS case.
We might still end up using AAs for medium term deployments however.
follower
We are based in Brisbane so it would be great if there were a few Arduino aficionados nearby who might be interested in helping. Thanks heaps for those battery life test results as well. Like the SF GPS datalogger I imagine getting the most out of sleep modes could have a lot of impact in terms of battery life.
fornsix
Thanks for the link. We've looked at using similar batteries for long-term deployments, and we still hope to, but there have been some issues relating to the max. current rating of these large capacity D- and C-cells. We were hoping (read pushing our luck) that a single cell would cut it, but the voltage drop/draw when the GPS was operational ended that idea. Using two cells in series seems to work, but we're yet to do proper bench tests to ensure they're going to last in the field. We're just using a diode to drop the voltage of the pack, which seems to work ok.
Cheers everyone, much appreciated.