I have had electrons out in the field for months, charging via solar panels and reaching the typical 80-85 percent charged nearly every day. I recently got a new batch of 25 more Electrons, and deployed them out in the field. There have been no changes to the circuit boards, hardware, or coding running on the systems. About half of the new electrons seem to be having issues either charging or reading the SoC of the batteries.
For the first few days of deployment the electrons show a normal charging pattern. Then they start to charge up less and less every day. They charge over the same time period as normally functioning units ( ie start charging at around 0715, charge steadily until about 1700, then discharge steadily until the next morning) but the peak charge does not reach as high as it should. Eventually the units die and the batteries have to be replaced.
New batteries do not change the charging curve. They are in full sun, nothing blocking them throughout the day. I took a battery from one of the units that said it was reading 2.1% charged, and when I put it in another unit it reported being at 64.4% without having had time to charge significantly. Looking at the units with the dead batteries, the red charging light is still on, but the batteries do not seem to be charging.
Any ideas on why the batteries suddenly stop charging normally? I have tried resetting the electrons, disconnecting them from power and reconnecting, and changing out batteries. All of the older electrons seem to be operating normally, it is just affecting the new ones I received a few weeks ago.
Thank you for any help!