Charging "noise"

bwilson4web

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#1
Hi,

I've noticed the periodically my SR+M3 will go through about 3-4 hours where there are micro-charging events going on:


From my T-Mobile account, it appears this the car 'phone home:'
Code:
07/16/2019,09:45 PM Internet Access -- 1.1269 MB
07/16/2019,07:45 PM Internet Access -- 6.3974 MB
07/16/2019,07:33 PM Internet Access -- 9.5351 MB
07/16/2019,05:40 PM Internet Access -- 85.4121 MB
This is different from typical charging patterns. For example, sentry mode has a series of brief, maximum charge events . . . a series of brief, square-wave shaped charging events. But these "noise" events have me curious about what is going on.

Sure it is a subset of "vampire" drain but I'm wondering if anyone has a more technical description of what is going on?

Thanks,
Bob Wilson
 
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Frully

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#2
My guess would be the smaller events are charging the 12v system powering the ecu/sentry, while the massive events are main battery. Strikes me the charger could be coming alive to power the dcdc converter to boost the 12v rather than putting additional cycles on the main battery.
 

JasonF

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#3
As far as I know, all tech devices with lithium based batteries (including the Model 3, iPhones, laptop computers) drain and refill a small portion of the battery periodically to keep it healthy when plugged in.
 

bwilson4web

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#4
My guess would be the smaller events are charging the 12v system powering the ecu/sentry, while the massive events are main battery. Strikes me the charger could be coming alive to power the dcdc converter to boost the 12v rather than putting additional cycles on the main battery.
I wonder if the folks doing CANbus reading might have seen this before?

Bob Wilson
 

JWardell

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#5
From the graph you show, it seems you are concerned with the ~200-500watt noise on the bottom?
It also seems that there isn't much resolution to your power logger, so tough to tell what is really being drawn here. You also have two graphs on top of each other of the same colored lines making it a bit more confusing.
Also how is your car plugged in, and can you give more details of your power logger setup?

With a normal Tesla mobile connector, it has a relay, and the car is totally disconnected when it is not charging, and Tesla lettering is solid on. Only power draw is ~3 watts for the adapter and LEDs. When charging activates (or if the car activates HVAC), you can hear the relay close and the Tesla lettering blinks in sequence. The car will draw the full power limit to charge, but with HVAC the draw can be much less.

One more thing: do you have sentry mode on? That will typically use 200-300W, but I don't believe it will draw from shore power, until the battery depletes 1-2% then it would turn on and charge back up for a short time. Is that what we are seeing?
 

bwilson4web

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#6
From the graph ....
The graph comes from our JuiceBox Pro 40. The metrics are stored on their server and I took a screenshot. I have not independently validated the data.

Before going further, I am more interested in instrumenting my Model 3 to directly measure what is going on. I’m not sure the CANbus metrics have enough details.

Bob Wilson