As mentioned had found a tempest online without hub… person doesn’t know where the heck it is. Battery is shot wouldn’t turn on and I couldn’t find those batteries online. So I had 2 c batteries I put in there 5000mah at 2.4v soldered a pigtail connection and the light turned on. So far everything is working I replaced mine in the meantime and going to see if this is a good replacement to the system or not.
2.4V is on the low end. The device might enter powersave mode. You can get those batteries from ali.
2.4v is nominal voltage. Idk why they put LTO batteries it’s not even a good battery NIMH is just as good or better than lithium and the voltage is more stable than alkaline. They had a perfectly good system with the air they could have easily made that the same platform with 4AA batteries charging and more readily available to the end user. They only thing I can see and I haven’t tested is the solar. It looks like it could be the issue there. With better solar panels it probably would be a more efficient design. Batteries are my kind of my thing but the important part is that the LTO has a memory issue going on. If you can’t charge the battery past a point consistently it will stay that way. The good news is it can be corrected by dumping enough power to over come the effects. The 2.4v LTO I took out I ran through a few loads and charges and was able to bring it back to 2.71v at full. I suspect this battery may have been in low state for a while… none the less I stand by a proven tech of NIMH and just would have made sense for the tempest to incorporate 4AA rechargeable to power the unit.
anything below 2.45V and the tempest goes into powersave mode (more so at even lower levels),
NiMH behave pretty bad when it is freezing. LTO batteries deliver power at much lower temperatures and are still usable at -30 degree Celsius. I don’t think LTO has a memory problem of any relevant level.
LTO also has the advantage that i can be charged many more times than NiHM.
Their previous design, called SKY, was running on 8 AA batteries. It had the advantage that you could keep running it even when there was no sun for a long period, but had the disadvantage that you had to go up your roof to change batteries every 9-12 months or so.
Here is the study https://pubs.acs.org/doi/pdf/10.1021/acsenergylett.2c00157#:~:text=Al-doped%20Li4Ti5O12%20(LTO),of%20the%20delithiation%20voltage%20profile.
8 batteries? I read in the manual 4. Wow 8 would have been even more fantastic. Why couldn’t they also make the power booster with solar cover and make that rechargeable too? Lots and lots of missed opportunities.
Yes the NIMH does have a higher cold operating temp. But who is operating at that cold? It’s not like going to make the battery burst or prevent it from having any volts… it can just operate with only the temp. And when the batteries get used they also heat up. They could provide two versions one being AA rechargeable and the other being LTO the should have also made it replaceable for cost. If you need to replace it you have to send the whole unit in. I made mine with a quick disconnect
the AIR unit takes 4 AA batteries, the SKY unit (the part that measures, wind, rain, brightness) uses 8.
Maybe take a look at the map of Tempest stations around the world and you should be able to see the answer to your question. I suggest you use a computer rather than a phone so you can see a larger view and have a faster render as you move and zoom the map.
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