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FYI on seeing restricted charge rates

FYI on seeing restricted charge rates

There have been many posts about PW not charging at the published rate. While there are some restrictions to comply with local ordinances I came across another criterion last week.
I noticed the PW was only charging at 1.7 kW while we had a net export of 2.5 kW. Over the morning the charge rate slowly climbed and only returned to >4 kW after a few hours.
It was a cold morning that day. The battery is housed in a unheated barn and was certainly below 4C.

I mailed Tesla support and they confirmed :-

Our latest firmware version, 1.11.2, contains some performance improvements related to the battery’s operation in cold climates.

The software will now operate like this:

- A scheduler will predict how much solar is likely to be produced on a given day based on the data that the battery records over the past week
- Based on this scheduler, the software may conclude that is worthwhile to heat up the battery cells to make them available for power conversion

In the case of yesterday, when your solar panels produced a lot of solar (>6000 kW peak around 12:00), the “heat mode” would’ve been triggered and the cells would’ve been warm enough to be able to convert power at full capacity.

...sure enough the following day the FW was updated from 1.10.2 to 1.11.2

Turbine | 18 février 2018

Tesla's specification for PW2 claims:
Operating Temperature
-4°F to 122°F / -20°C to 50°C

I have 2xPW2 installed in the UK. Because of the above, I elected to mount the batteries on an external wall.
I too have suffered from battery shutdown when the ambient temperature fell to ~0 Celsius.
Had I known of this operational; limitation, I would have mounted the batteries internally.

The PW2 fails to meet the published specification; not a problem if the limitations are stated in the specification.

sashton | 18 février 2018

It does appear that the firmware update to 1.11.2 has had some effect on the battery behaviour as the fan, that previously appeared to run continuously when the battery wasn't on standby, is not running in cold conditions.
Sadly the battery is another symptom seen after the FW upgrade in that the battery does no longer discharge to a reported 0% but stops around 5%. This is not reported by the app but is recorded by \api\system_status\soe
I'm led to believe that this is a reserve set to be used heating the battery in cold conditions but would have thought it better to take that energy from the excess PV .... maybe I'm not seeing the scenario fully.
Hopefully this reserve will not be taken when the ambient temperatures rise.
I saw 1.12.0 FW arrive last week. Plus ca change.