If you wanna be really energy efficient use a stand alone MCU. You can use a lower clock frequency, a better dc/dc converter. Also turning the sensors off between readings will do wonders, as well as sleep for the MCU. If you read the sensors every minute, the MCU and the sensors could be off or sleep for 50 secs (just an estimate, considering startup times for the sensors).
Go to an EBIKE mechanic. They probably will be disposing of under-performing batteries (replaced by warranty), usually 36vdc or 48vdc (52vdc) with a capacity of 400Wh to 900Wh.
The reason a mechanic will have "warranty" batteries is that a "new" ebike battery will have the capacity written on it, and a "load tested" battery above 80% of the noted capacity is considered "new." If the load test shows below 80%, the battery should not be considered "new," and the manufacturer should replace the battery for under-performance. ebike batteries are expected to perform as "new" (with slightly diminished capacity) through three years of use, when the capacity drops significantly, yet these batteries will be usable at a diminished capacity for many years. 400Wh should give your project power for a week.
Or that the battery capacity is 38Ahr.
If you manage to fully charge it with a solar panel.
Yes. That will never happen unless the system had a very large collector and MPPT with enough amps-in (from the panel) to produce the required amps-out to pack the battery full.
One would swap batteries and re-charge on commercial power.
I was going to mention that too but wasn't sure if he would get it. That device isn't the worst idea in soar and batteries, but it is close. Before I built my solar system (7,200wH battery, 1,080W panels, 3,000W inverter) I thought I knew what I needed to know since I used to be an industrial electrician. 2 years of studying later I realized I knew nothing at the start.
If it's in the garden and on property, get a Battleborn 100aH 12V LiFePO4 battery and recharge with a proper charger on a long extension.
What amazes me is that the so called 'adverts' that quote lithium battery capacity on Internet sales sites such as fBay, Bli and Bmazon are often clearly inflated by 10 or several times more.
Yet fBay, Bli and Bmazon seem to do seem to do enough to prevent such dishonest advertising.
Can you give me an example, I only know of the scams on AliExpress with the 18650 cells.
See post #7, which I commented on before.
Ok, but are you talking about the 18650 labelled as 5000mAh and I even saw a 9000mAh. Pure poppycock. You can get a good estimate of the capacity of a given cell by weighing it. For each chemistry there is a mAh per gram spec, just multiply that by the weight and estimate what you think the packaging is and multiply again. I think 90% is fair. The valid cells have a capacity in the 2,000 to 3,000 mAh range and I even have some as high as 3,500 mAh. I have a high quality tester that does a full cycle to measure the capacity.
Nothing in that ad makes sense. It shows 40mm thick so that means 7 cells wide but 10s3p says 30 cells. 10s is 36V but 3 p is at best (3 x 3500 = 10,500mAh)
That is an easy scam to spot, as is the ads on AE and Amazon for 5,000mAh and even 9,000mAh and more. The worst are those labelled as 2,400 or 3,500 which is 'normal' but when you test them they are 1,200. Some will weigh much less therfore have les capacity.
Can a 10W 12V solar panel, 2 3.7V 18650 Li-ion batteries, a Charge controller be used ?
Link to Solar panel:
Link to batteries:
Link to Solar Charger:
I tried using chatGPT to help with the design. I am from the Caribbean therefore, I need to source the parts quickly for this school project.