Power supply for a wearable device based on photon

Hallo, sorry if i am not posting in the right place, but still a newcomer.
I’d like to design a wearable with particle (photon or P1?) for detecting fall. I found i could assemble an adxl355 as a accelerometer but need to supply energy and keep size as small as possible. I’d also like to recharge by induction…
Any suggestion?
More:

  1. i am just an omonyme of the Banzi of Arduino boards
  2. i can imagine that this question can appear silly , but i am not an expert, so … please be patient
    Thank You
    Massimo

@mbanzi, have you considered the power requirement for WiFi devices versus BLE? If you search this forum you will find many such topics battery discussed.

BLE should be better if i need to use just one terminal close to the wearable … i would like it to connect ito a mobile device when close and/or outside and to home SSID when at home.
The device should also be operational H24 with a alternate one switching when the first is charging. Power requirement … i know i should evaluate but yet do not have an idea of consumption and just was looking for some hint.
I’ll have a look to forum discussione, but a i already did a quick search and could not find what looking for. I’l check with more accuracy now that you say that probably something has already been discussed .
Thank you @peekay123

@mbanzi, the Photon can consume 40-80ma while operating in a WiFi connected state. It can peak to 350ma while establishing a WiFi connection with an access point. To be frank, the Photon is not designed for 24 hour, low power operation.

are you talking about photon or P1? are there substantial differences between the full photon and this one?

@mbanzi, the Photon is a P1 with an RGB LED, a buck regulator and a few passive components.

here i am back … what about a battery like the one in
http://kayobattery.gmc.globalmarket.com/products/details/rechargeable-polymer-li-ion-battery-604883-with-3-7v-3000mah-646074.html
I guess if it is possible to find smaller ones, but could it be suitable to provide h24 supply for photon?

Theoretically, a 3000 mah battery should be able to power the Photon (@ 80-100 ma) for 24 hours, but you might have to test that to see if it works in practice (it might depend on how many times the devices loses and then has to reconnect to the internet, and how often you are transmitting on the WiFi).

Do you need it to be connected to the cloud all the time, or only when a fall is detected? There would be a big difference in power consumption between staying connected to the cloud all the time, and just keeping it “operational” (operational meaning reading the accelerometer, and connecting to the cloud when it detects a fall).

Thank you Ric.
I expect it to be connected either to a mobile (when out-home) or to a edge server when in-home.
The “patch” should be always worn and just send signal in case of possible fall or the close to discharge …
I was also thinking to add a temperature sensor and a heart rate monitor, to correlate data with the fall and provide further info , but it depends on the overall size and on the consumption …
Indeed a battery pack of 3000mah is non t so small … any suggestion?
also because i was thinking at an induction charging antenna and need to understand how it wold interfere with the wifi one …

It doesn’t need to be connected to the internet all the time to do those things. There’s no magic bullet here, you either need to have a large battery, or have it only connected when it detects a fall. It could also connect several times per hour to check in if you want. What else do you want to do with this that needs full time connection? I don’t see anything in your posts that would require full time WiFi.

1 Like

Hallo and sorry for resuming a long forgotten thread.
Indeed I have been reasoning on the overall architecture and components of my project, selecting a bundle consisting of the Particle Photon, a SP Shield 13626 and the MPU 6050.
The identification of a fall from the accelerometer would trigger the pairing to a close wifi network, the reducing consumption. I expect the photon to remain in almost permanent sleep mode unless a fall is detected and periodical check on the operational status of the bundle. Following your suggestion.
I would like to test with a 2Ah and in case with a 3Ah Lithium Ion Battery.
Do you think it would be enough?
Thank You
Massimo

I am not familiar enough with the 6050 to know if this will work or not. As far as I can tell from the data sheet, it appears that you can program it to wake up the Photon, but I don’t know how flexible this feature is. If you can have it wake the Photon after detecting whatever level of motion you think is necessary to detect a fall, then I think it will work for you.