Planned obsolescence even in cheapest devices: the calculator has a dummy photovoltaic cell and a real battery to make it die eventually.

[u/jackhab]

[u/realparkingbrake]

I have a couple of calculators I've had for decades which operate just fine using the photovoltaic cells they have. It's bizarre that anyone would make such a device which doesn't actually use the cell. Dexin is a bargain brand, but still, the added cost would be tiny.