This is the PBA’s behavior when it powered by batteries, to preserve their lifetime as a backup power source for times when the Tempest doesn’t have enough solar power to maintain an adequate charge.
When the PBA is powered by external power, it becomes the primary power source and the Tempest’s internal batteries serve as the backup power.
The math for what happens when the PBA is connected to an intermittent source of external power (like landscape lights mentioned above) is an exercise for the reader (although 277V is the wrong answer )…
Below the installation instructions there is a “Power Options” section which describes the behavior. As has been explained above in this thread, here is the official description.
I like you prefer to attach the AC to the tempest to fully charge and then disconnect; however there lies the rub and why we need information from Weatherflow.
Mine charge to 2.5 / 2.6/ one to 2.7 and stay there.
I would like to know what the expectant levels and behaviour should be when under AC.
I had to buy a new tempest as support said the controller was US; however it works fine on all power supplies but never charges fully on AC or batteries.
Batteries do not charge the Tempest to full but that is understandable as I believe they are a safety net by design.
Therefore a published article ( @dsj )would be good so we all understand what to expect and can continue to manage without resort to Weatherflow support.
Not a safety net, it is so the batteries used in the PBA are not unnecessarily drained.
Read my post above your post. Fully charged for an LTO battery like in the Tempest is 2.6-2.8V. There is very little energy storage above 2.6V. I don’t know what else WeatherFlow can say other than what they have already said and has been posted multiple times on the forum and in this thread.
When I leave my Tempsts on the PBA with supplied AC Adapter. . .Both Tempest devices will charge up to max voltage (2.78v & 2.l81v respectively). The voltages do Not remain at that constant level. . .especially during the 13 days in January that I had it set up that way. This is the behavior that I observed: When Tempests placed on PBA with AC Adapter. . .after a few hours. . .the battery charge controller circuit will allow the “max” voltages of each Tempest to drop off by a few hundredths of a volt. i.e. 2.78v on one Tempest. will drop back to ~2.76v for as much as 30 mins — even while on PBA with AC Adapter. Then. . .the circuit will “kick-in” and charge the battery back up to 2.78v. Same with the other Tempest: the max voltage (on PBA with AC adapter) will charge up to 2.81v. . .and stays that way for hours. . .then it will start to drop back down to ~ 2.79v and stay that for several tens of minutes. . .then it (too) will kick back up to 2.81v.
My conclusion / observation is this. The Tempest on a PBA with the AC adapter charges up the Tempest. . . just like the solar panels would do. When the charge controller circuit "thinks’ that the battery has had enough. .it (charge controller) stops charging – even while PBA is still on AC Adapter is still attached – and allows the battery to drain back down a little bit until it (charge controller) “feels” that it is time to “boost up” the battery again. Then the voltages go back up to max (2.78v / 2.81v). I observed this “cyclic pattern” thru out the mid-January Arctic episode.
This is “cyclic pattern” by the PBA on AC adapter is exactly similar to the solar panels charging up a Tempest in Full Sun. Then all-of-the-sudden. . .a cloud appears right over the sun (providing shade). . .and the charge controller circuit “knows” that there is no more sun (temporarily). . .so the battery begins to draw back down. Then. . .that cloud floats away and the sun once again shines directly on the solar panels. . .and the voltages go back up to max.
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