Remove 'batt' from JSON payload? about gw HOT 16 CLOSED

We may leave the Indicator in to see if the device is on external power or running on battery.
Suggestion "p":"", where is E or B.

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OK. (I'll modify documentation)

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Call it pow, please.

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Maybe vehicle batt level makes sense instead?

Stefano Costa
R&D, Managing Director
M. +39 335 6565749
Skype stefanocosta.bluewind
Twitter @stefanobluewind
www.bluewind.it

Il giorno 02/ago/2014, alle ore 08:38, JP Mens [email protected] ha scritto:

Should we remove the batt level from the JSON payload for GW devices? It's mostly the same value, and if the battery does die (it happened to my first device) the device probably won't do much anyway ... Saves a few bytes, in particular as the information doesn't seem really valuable.

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This proves to be very useful on similar applications, telling what's wrong under strange situations

Stefano Costa
R&D, Managing Director
M. +39 335 6565749
Skype stefanocosta.bluewind
Twitter @stefanobluewind
www.bluewind.it

Il giorno 02/ago/2014, alle ore 08:52, Christoph Krey [email protected] ha scritto:

We may leave the Indicator in to see if the device is on external power or running on battery.
Suggestion "p":"", where is E or B.

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The value we're getting isn't vehicle battery level; it's the battery level of the Greenwich. I think we'd need CAN BUS for the former, but that's a feature which is far away ... ;-)

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AT+SBV -> (e.g. 4.4V) indicates the supply voltage of the module a.k.a. the voltage suppled by the vehicle or battery.
Once we start using deferred shutdowns or alerts, we may find it helpful to have this.
AFAIK vehicle battery voltage is not available w/o CAN BUS
Currently the power indication is hardcoded in the app as "E", so it wouldn't help

We may use the info provided by
AT+SBC which is currently not monitored by the app except the undervoltage warning

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Might be possible using an AD converter (just an additional cabling on the connector) but @Matteo knows if this is supported, I'm not sure.

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If Greenwich is connected to the vehicle battery, you can read the voltage using "getVIN()" or "getDoubleVIN". See PowerManager class in the Choral library.
These methods read the Greenwich power line voltage.

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"batt" (optional, see $set fields=) now contains external voltage, e.g. "batt":"12.2V".

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I'd like to revisit and discuss this again. We now have vehicle battery voltage in the JSON payload, but is this really useful? Isn't a vehicles battery pretty constant at 12/24V?

As I was telling you yesterday, JSON with the Greenwich' battery level (e.g. 3.7V) was a lifesaver for me in determining why a few devices stopped reporting (I saw their battery drain, thus proving they weren't attached to power).

If you all think vehicle voltage is better; fine, otherwise I'd like to get back to Greenwich battery, if possible.

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Let me comment on this. Based on our experience both values are relevant under different situations, and would help having them available. Maybe less often than position, or at request.

I agree that vehicle battery voltage is constant with IGN on and engine running; but can reveal issues if dropping too fast when stopped, and an interesting feature is giving its value once every 16/24 hours while being parked (trucks, trailers) being an expensive piece of equipment.

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Maybe we could publish both battery levels at the "t":"T" type (e.g. maxTime) as Stefano recommends? It probably is overkill to publish battery levels at each location change, but could we publish them periodically and/or when levels change? {"battv": "12.2V", "battg" : "3.9V" } ? (v = vehicle, g = greenwich)

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I think publishing retained messages to

.../batt/v  12.4
.../batt/g  3.7

would probably make more sense in this case, and it matches what we do with .../gpio and .../sw.

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I had the same idea

owntracks/gw/356612027383852/voltage/batt 4.4V
owntracks/gw/356612027383852/voltage/ext 12.2V

Will be updated as soon as voltage changes significantly (currently hard-coded 0.1V)

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Documented here.

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