I bought a bunch of eneloop pro, but using them in connected thermostats is always displaying “low battery” even after just fully charged. This is when I discovered that they are actually 1.2V
It really came as a surprise, is there a catch? Are they only good for low power stuff like remote controls?
Edit: it seems they do exist in lithium. Question remains why are the NiMH only 1.2v and why are they the most widespread?
It boils down to chemistry. The nickle-metal-hydride chemistry used in rechargeable batteries just don’t produce 1.5V (explaining why is a lot more complicated), while the alkaline chemistry in non-rechargable batteries produces slightly more volts.
In the same vein, lithium-ion batteries produce around 3.6V, while lead-acid produce about 12.4V.
Lead acid is actually closer to 2v/cell. Car batteries are 6 cells in series.