SparkCore Battery Life

Hi,

I went on the electric imp route, and was wondering how the devices compare for battery life.

What are the estimates of life using the battery shield (for a device that’s passive 90% of the time)

The Core now has two sleep modes :
Mode 1: Puts the CC3000 to sleep
Mode 2: Puts the entire Core to sleep (deep sleep?)

I’ll to run the Core through a few tests to give you accurate numbers. Stay tuned!

Mohit

@theboyknowsclas while we wait for @mohit’s tests, the quick answer is that it depends on how much battery you’ve got, how often the device is connected, and how often you put the whole thing into deep sleep. It’s a trade-off between responsiveness and battery life; you could extend your battery life for years if you put the Core to sleep for days at a time and only wake it up to fire off quick messages.

Sorry if this has been documented elsewhere, but how do we switch between the sleep modes ? Would “tinkering” with the factory firmware be the best place to start ?

Just to share, we have recently powered the core (completely stock) using a 9v battery (of course we regulated it down to 3.xx v), the Core consumed on average 140mA constantly (which is pretty consistent to what you guys have documented) and the battery went flat in roughly about 8 hours of operation (most of the time the Core was just being idle).

That’s not a PP9 battery, surely?

I found that my core uses considerably less than 140mA. Take a look at this picture.

Note I am using a DC-DC converter, rather than a regulator, so (in theory, at least) far less power is wasted.

But I do wonder why my core is using so little current compared to the numbers you are seeing and the team has been suggesting. I am doing nothing clever to save power - no sleep modes or other power saving techniques.

The only reason I can think is that so far I have been using the core very close to the router. Does the CC3000 use less transmit power when its getting a strong signal from the router?

Paul

The penny has just dropped! My DMM is measuring about 46mA @12V, which is about 0.55W. Assuming the converter is around 90% efficient, that means it’s output is around 150mA @ 3.3V.

Very nice project there @PaulRB :smile:

You’re right… it wasn’t a PP9, we used PP3 battery as we have limited space to work with.
I’m still hoping to bring down the consumption by effectively turning it off when not in use.

There’s an interesting discussion on this topic on TI, apparently CC3000 draws very little power in its sleep mode: http://e2e.ti.com/support/low_power_rf/f/851/t/162231.aspx

Thanks @elraj. I would definitely recommend using a DC-DC converter as opposed to either external, the core’s internal (or both) regulators. If you need to get 9V down to 3.3V, regulators are inevitably going to waste two thirds of the battery’s energy. By comnparison a DC-DC converter should give 80 or 90% efficiency. The one I am using is pretty small as you can see.

Note sure yet how I can make use of sleep modes in my project. Right now, variables are used to get the sensor readings to the web page, and if the core is asleep, the updates will fail and the core won’t automatically wake, I suspect, if the WiFi is not running, it won’t even know it needs to!

Paul

Oh, I meant to say PP9! 8 hours at 150mA? That’s 1.2Ah! Is it a Lithium-based one?

Here is a graph of battery voltage vs current draw for a fresh Energizer PP3, when powering a quiescent core running tinker, connected to the cloud (e.g. breathing cyan.)

As you can see, about 2.5 hours with the stock firmware & using the on-board regulator.

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OK, thanks @AndyW so that’s for a PP3, a small 9V battery. But @elraj says he is getting 8 hours life from a PP3. Are you sure its not a PP9, the large 9V battery?

If elraj is loading an app that uses the low power modes, then 8 hours is quite possible, but my plots are for vanilla core, out of the box with tinker.