I’m considering making a rather large Mesh network and am new to the associated hardware (I’ve used the Electron before, though). I have some questions that maybe I’m just being dumb about looking for answers, but I haven’t found any concrete ones. Here goes.
What is the battery life for a Xenon acting as a repeater, not an endpoint? I read somewhere it has to remain on forever so as to not disrupt the network, though obviously a small percentage went offline it would still work).
Is it feasible to have a receiver that is running only on a battery? I know the Xenon is designed for low power consumption, but this would have to run for a pretty long time on its own. I also read something about a super low power mode, though I don’t know if that applies to repeaters or endpoints.
What would be a likely range for a Xenon assuming it was outside with fairly minimal obstruction? How much farther could that reach with the 2.4 GHz Antenna sold by Particle?
Right now, you can't change whether a Xenon is a repeater or an endpoint... it is both and can't be changed. If the Xenon is sleeping, it can't relay mesh packets. If the Xenon is awake, it has full mesh functionality but consumes more power. In the future you might be able to designate a role but for now, the mesh functionality is pretty basic. To estimate your battery run time you need to know what the capacity of the battery is and the average current draw of your circuit. Or you can work backwards: if you know the desired run time and the average current draw, you can calculate the battery size to accomplish the run time. There are some power draw measurements for the Xenon posted here in the community but I don't believe that has made it to official Particle documentation yet. The power consumption of a mesh device is only one part of the equation; you also need to know what the sensors and other external circuity will draw. @Rftop has done a lot of battery/solar run-time testing and current measurements and may be able to comment further. See his posts:
Currently, there can only be 10 nodes on a Mesh network including the gateway. The larger networks are future functionality that is being worked on. How large is large?
What would your "receiver" do? In a mesh network, you have the gateway (that handles internet communication) and then nodes or endpoints (for now only Xenons that gather data and publish to the mesh or directly to the cloud). A gateway needs to be always on in order for a node to publish direct to the cloud. A gateway may draw too much power to remain on battery indefinitely without a solar recharge or some other solution.
How long is long? What type of batteries are you using? What temps will they batts be subjected to? What are your recharging options? Too many additional questions to make recommendation on vague requirements.
It applies to both... there is a very low power mode that draws something like 10uA but there are a bunch of caveats. You have to consider the selection of all of your external components to make sure their quiescent current consumption doesn't adversly affect the overall system. (i.e. if you have a LDO voltage regulator that burns 10mA at idle, the lowest sleep mode of the mesh device desn't really matter since the LDO will be orders of magnitude higher.) I think you need to state your exact use case before delving into which sleep modes are best.
Thanks for helping! My apologies for the unspecific questions. Let me try to clarify.
I'm basically trying to make a network with a sensor taking readings every 2 hours. Ideally, the battery would last as long as possible without direct maintenance. I've looked at solar in the past while working with an Electron, and the cost of a panel large enough to void the drain was too much for me. However, I don't know what that looks like for the lower-powered Xenon. I'll look into that.
When I say large, I do mean more than 10 nodes. Is there any work around, or word of when that expanded functionality will come to be?
I'm trying to run for as long as I possibly can. I'm planning on using an additional battery manager, but any minimization will help. I'm aiming to use LiPo batteries, probably 6600 mAh. I can use solar, but as stated above I'm afraid to get too expensive. I'm planning on just manually recharging it unless a better option is out there.
I really appreciate you getting back to me so fast. Thanks!
You could have your Gateway push the Sleep Time, or Time-To-Wake to the entire Mesh.
This would be a synchronous sleeping network where "hopefully" all Xenons wake at approximately the same time to re-establish the Mesh Network every 2 hours. This may be optimistic this early in the Gen3's firmware development.
If solar is an option then you can just size the panel and Li-Po (or SLA w/ charge controller) accordingly as @ninjatill explained. There are several threads dealing with estimating the Power Budget.
You could leave the Mesh Network alive 24/7 and only revert to Synchronous Sleeping when the batteries start getting low after too many cloudy days, as a last resort when you exceed your Power Budget assumptions.
I've used a lot of $3-$5 Solar Panels (6V) with Borons. The Xenon is obviously different, but you might be fine with using a 6V panel. Maybe someone has Solar Xenon data to share ?