We have been informed that there are batteries on the market carrying the Maxell brand that differ from genuine Maxell batteries. We have examined these batteries and conclude that both batteries and packaging are fake.
Each battery carries the “maxell” logo and code number “SR621SW”, which indicates the battery is a silver oxide battery. However, our analysis shows that these are not silver oxide but alkaline button batteries.
Silver oxide batteries are ideal for use in watches as they provide a stable voltage and low risk of leakage.
Alkaline button batteries are cheaper, their voltage weakens gradually with use, and they have a higher risk of leakage than their silver oxide counterparts. Therefore, they are not suitable for use in watches. Moreover, alkaline button batteries have a lower capacity than silver oxide batteries and last much less time. There may also be safety concerns if the button batteries have been manufactured without adequate quality control.
Please note that Maxell cannot guarantee that use of these fake batteries will not result in battery leakage, shorter battery life and even battery explosion. The differences between genuine Maxell batteries and the fake batteries are shown below:
1) Appearance Fake battery
Genuine Maxell battery
The minus side of the Maxell silver oxide battery has been polished to reduce contact resistance.* We could not find any such polishing marks on the fake battery.
*Some models are gold plated instead of the polishing for better electrical contact.
2) Battery voltage
The open circuit voltage (OCV) of a new silver oxide battery is between 1.580 and 1.620. The voltages of the fake batteries are between 1.522 and 1.556. Based on this OCV, we can conclude that these are alkaline button batteries.