CR2016 vs LIR2016
The CR2016 and LIR2016 share a 20 by 1.6 mm case and little else. The CR2016 is a single-use 3 volt lithium cell rated 85 to 90 mAh. The LIR2016 is rechargeable lithium-ion at 3.6 volts nominal, about 4.2 fresh off the charger, and holds only 18 to 25 mAh.
| CR2016 | LIR2016 | |
|---|---|---|
| Chemistry | Lithium manganese dioxide (Li/MnO2) | Lithium-ion (rechargeable) |
| Voltage | 3 V | 3.6 V |
| Diameter | 20 mm | 20 mm |
| Height | 1.6 mm | 1.6 mm |
| Capacity | 85-90 mAh | 18-25 mAh (rechargeable) |
| Also sold as | DL2016, ECR2016, BR2016 (wide-temp variant), 5000LC | – |
Voltage is the reason this is not a swap. A device built for a CR2016 expects 3 volts, and a freshly charged LIR2016 hands it up to 4.2. Some circuits tolerate that, some behave oddly, and some are damaged, and there is no way to tell from the outside which kind you own. Car key fobs, pocket calculators and digital watches, the CR2016's usual homes, were designed around the primary cell and should get one.
Capacity makes the swap pointless even where the voltage is survivable. At 18 to 25 mAh the LIR2016 carries roughly a quarter of what a CR2016 holds, and an ordinary fob or watch has no way to recharge it, so it runs down early and then has to come out for a spell in a separate lithium-ion coin charger. Its self-discharge of a few percent a month also rules it out as a spare that sits in a drawer. The stacking habit of this size makes things worse. LED novelties and some fobs stack two CR2016s for 6 volts, and two freshly charged LIR2016s in the same stack would put out about 8.4.
The rule runs the other way too, and that direction is the dangerous one. A device that charges its own cell, such as a slim rechargeable wearable, must never receive a CR2016, because charge current into a primary lithium cell can make it leak or rupture. Solar watches in this size commonly use the ML2016 instead, a 3 volt rechargeable holding about 25 mAh, and that is not an LIR2016 either. Read the full code on the cell you removed, prefix included, and buy exactly that.