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Tesla Powerwall (2) Calibration Cycles

Toodles · 2026-09-28T10:44:17Z

I have recently noticed that my Powerwall 2 has taken to autonomously carrying out a calibration cycle where the battery is charged to 100% and then discharged to my setting of 20%. In itself this is OK (ish) but as during the high usage months I will have the ‘charge from grid’ option switched on, I am concerned that as I have not control over this process, recharging may well occur during peak tariff times! Google via Alexa informs me that I cannot switch this function off and I am concerned as the calibrating cycle may be carried out as frequently as every 30 days and that recharging might well occur at the most expensive times. Has anyone any knowledge or experience with this ‘feature’ please? If I can assume that all recharging would be carried out during the cheapest times of my (Cosy) tariff, then it will just leave the matter of what happens when a ‘flat’ battery coincides with a power cut? Concerned, Toodles.

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Old_Scientist

(@old_scientist)

Prominent Member Member

Joined: 2 years ago

Posts: 573

02/10/2026 3:15 pm

Posted by: @toodles

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@old_scientist The operative word there is ‘notice’, it would be nice if the app could send the operator a brief email notice of intent wouldn’t it? Having to keep toggling the settings is fraught with possible whoopses resulting in unintentional actions. With advance notice, one could plan how to deal with the recharge cycle timing. Regards, Toodles.

Yes, I agree. I give Tesla my thoughts on the topic every time I speak with them on the phone, so I think they are well aware that calibration is a subject many customers in the UK are unhappy about.

I see no technical reason why the software couldn't take into account ToU tariffs when scheduling a calibration if Savings mode is in use at the time, but clearly this is not something they have seen fit to do (yet!)

Samsung 12kW gen6 ASHP with 50L volumiser and large radiators. 7.2kWp solar (south facing), Tesla PW3 (13.5kW). Net Zero

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Papahuhu

(@papahuhu)

Honorable Member Member

Joined: 1 year ago

Posts: 434

02/10/2026 3:52 pm

@old_scientist

I don’t know, but postulate that perhaps there are good technical reasons why it’s not possible. Maybe the calibration event needs to be at a constant and continuous charge and discharge rate and that it can’t accommodate a TOU structure. For example during charging, you may not want to have a mixed charge/discharge cycle.

A very very long time ago I wore the hat of a metrology scientist, calibration methodologies are only valid if performed under specific and controlled conditions.

This post was modified 4 minutes ago by Papahuhu

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Toodles

(@toodles)

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Joined: 4 years ago

Posts: 2983

Topic starter 02/10/2026 3:57 pm

@papahuhu The strange thing is that for the first 4 years of the Powerwall’s lives, they have not needed this particular type of TLC to function well at all. Maybe as they approach middle age, they need some TLC to continue giving of their best? Regards, Toodles.

Toodles, heats his home with cold draughts and cooks food with magnets.

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