Is my Tempest battery defective?

Station ID is 36049. Starting a month or two ago, my Tempest no longer seems to increase in charge on a daily basis. When I first got it, as shown in the image, voltage would increase to about 2.8 every day that I had some solid sun.

Now it’s just flat even when I have solid sun:

[I will continue this topic is a second post b/c this forum will only allow me to add 2 links as a new user].

[continued from above]

And here are some images showing voltage over the course of 12 hours or so, and the corresponding solar radiation.



Is my battery defective/dying? What are my next steps?


Doesn’t look normal indeed. Is something blocking 1 or more panels ?
If nothing changed in the setup, open a support ticket. They’ll help you out.

Nope, nothing block panels. I check for cleanliness every few weeks. Nothing has changed.

I’ll open a ticket. Thanks.

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Mine just started doing the same thing. less than a year old. started support ticket.

Mine has great sun exposure but rarely goes over 2.5v. I’m guessing that’s not normal?

See my pictures. It should go up noticeably during periods of significant sun exposure. Mine used to go up to about 2.79 every day from ~3 hours of sunlight.

Interesting… Mine has also been acting the same way within the last few weeks. Have had the device for 11 months. It charges, but it just stays at a consistant 2.55. Has slowly allowed itself to go to a 2.6 today, but it’s been bright sun all day; and used to shoot to 2.80 within a few hours of bright sunlight.

Only thing I can wonder is that maybe with the higher sun angle, the sun isn’t directly hitting the solar panels as directly as earlier in the year ? I do remember that it wasn’t until August of last year that I started hitting charge numbers above 2.6.

2.5 is a bit low. Usually a unit would charge to at least 2.6 and maxes out at 2.8. There is however very little energy stored between 2.6 and 2.8V. So if the unit doesn’t go over 2.6 but otherwise works just fine, I wouldn’t worry. If it doesn’t go over 2.5, that might be suspicious.

My Tempests have never charged like your graph. My original was replaced after about two months due to multiple sensor failures. I’ve had the replacement for about 11 months now.

Charging never starts until the battery has dropped to 2.45V. Once it starts to charge it will continue to charge for the remainder of the day.

When the sun goes down it stops charging. It doesn’t matter how far above 2.45 it charged before the sun goes down but at that point it will not charge again until the voltage drops to 2.45.

It might get to 2.48, 2.52, or if I’m lucky and charging started early in the day it might get as high as 2.56 or above. I’ve only seen above 2.6 two or three times. Once the sun goes down there is no more charging until it falls to 2.45.